View Full Version : Why Recap Speakers and When?


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Scorpion8
08-17-2006, 10:47 AM
Howdy --

Been searching AK and reading old threads about recapping speakers. This was a good one: http://audiokarma.org/forums/showthread.php?t=74979&highlight=recapping+speakers.

My question however isn't answered in any of the posts. At what point does a speaker need to be re-capped? How many years after original purchase? How long in storage without any use before it's time to re-cap? Do the caps last longer if the speaker hasn't been played, or if it's been in constant use?

Thanks for the help!

MarkAnderson
08-17-2006, 11:14 AM
I tend to think that 25 years is a good rule of thumb, based on stuff I've read and my own limited experience. A cap will "dry out" over time which will limit it's ability to pass signal (there may be more to it than). Case in point: my recently purchased Seeburg DSS1's Altec driver's output was virtually non-existent 'til I replaced the x/o cap.
Whether to use electrolytic or polypropylene (or better) caps is mostly a matter preference. Replacing old electolytics with polypro's can net a cleaner, often somewhat brighter sound, but doesn't necessarily maintain the speaker's original sonics. Just depends on what your after, I reckon. - Mark

subdermis2000
08-17-2006, 11:27 AM
Hey Mods,

This may be a good topic for a sticky. I know I've searched AK many times for info on this topic.

Celt
08-17-2006, 11:59 AM
As mentioned, caps deteriorate over time. Manufacturers tend to use inexpensive components when making crossovers too. Higher quality caps, non-inductive resistors, robust inductors and better wiring can make a huge difference in performance. Also replacing those awful "clip" type terminations with quality binding posts helps.

subdermis2000
08-17-2006, 01:03 PM
Thanks for the sticky Celt :thmbsp:

Celt
08-17-2006, 02:52 PM
Thanks for the sticky Celt :thmbsp:
You're quite welcome. :yes:

TrexT
08-17-2006, 03:10 PM
If I replace a cap it's because I noticed a problem in SQ or if I replace a driver like a tweeter. I have several 30+ old speakers that have the same caps in them and they still sound very good. As a matter of fact the Heritage speakers (36yo) I just replaced the tweeter caps when I put in new tweeters. The only other cap in the crossover was for the mid and it still sounds fine.

Celt
08-17-2006, 04:25 PM
I can guarantee you caps can drift way off value as they age. In this case, it means the cap in question and its related driver are no longer crossed at their intended frequency regardless of sound quality.

BECtoo
08-17-2006, 07:44 PM
Over time the crossover caps get high in ESR. ESR (equivalent series resistance) is the sum of all the losses in the cap expressed as a value of an equivalent resistor in series. The average 30 year old film and foil cap like the one in the picture will still test good for capacitance but be high in ESR. Most read around 1 ohm ESR at that age, but the sky is the limit. The one in the picture has an ESR of 68 ohms. The tweeter signal was not going to make it through this cap even though the capacitance is still pretty good at 1.9 uF. ESR meters like the one in the picture will set you back over $500.00 in case you want to run right out and get one for testing your caps.

Good caps (polypropylene) will read around a few hundredths of an ohm when new.

Bob Crites

TrexT
08-17-2006, 08:08 PM
Will old(25+yrs. old) x-over caps harm drivers in the path? That would be my only concern. Thanks for that ESR info. :thmbsp:

BECtoo
08-19-2006, 09:47 AM
The old bad caps are not likely to hurt the drivers but a case could be made for how that is possible. When the caps increase in ESR, the impedance of the circuit changes and therefore the crossover frequency points will also change. When this crossover point changes enough, you have drivers trying to produce frequencies not inside their operating range.

Bad sound and loss of efficiency is the best reason to change them.

Bob Crites

pocketchange
08-20-2006, 01:15 PM
As reasonable as Mr. Crites XO services are, I'd be sending him all of my XO situations. No matter what the reason...
pc

shocley
08-20-2006, 01:54 PM
Are there any guidelines on ESR of electrolytic capacitors vs. film types?

What I'm afraid of is replacing old electrolytics with new film capacitors, and the lower ESR of the new caps giving the tweeters more volume, resulting in my nice old speakers turning into shrieking monsters.

How about a polypropylene film cap + small resistor to approximate the electrolytic? That'd give the presumed benefits of low distortion yet preserve the original ESR, wouldn't it?

BECtoo
08-20-2006, 05:59 PM
Are there any guidelines on ESR of electrolytic capacitors vs. film types?

What I'm afraid of is replacing old electrolytics with new film capacitors, and the lower ESR of the new caps giving the tweeters more volume, resulting in my nice old speakers turning into shrieking monsters.

How about a polypropylene film cap + small resistor to approximate the electrolytic? That'd give the presumed benefits of low distortion yet preserve the original ESR, wouldn't it?

Electrolytics also have an ESR about equivalent to Polypropylene caps then they are new. They go up in ESR over the years just like others. Mylar caps start out life with an ESR higher than I like to see in caps.

Absoultely the worst new caps I have tested are the new expensive PIO caps. ESR is just at about the point where I would replace them when they are brand new. The ones I tested were at about 1/2 ohm.

Remember that ESR is a measurement of everthing a cap does that is not what a cap should do. If you want to attenuate a signal, the absolute worst way to do that is to depend on getting attenuation from poor performance of caps. That poor performance is not a stable thing. It will continue to get worse with age.

So, in most cases when new caps are put into a crossover the high end gets brighter. That is when you should consider break-in time. That is for your ears not the cap. The speakers are likely sounding just like they did when they left the factory. You have perhaps not ever heard them sound that way or it has been a very long time since you heard them sound right.

Bob Crites

subdermis2000
08-23-2006, 07:24 PM
Electrolytics also have an ESR about equivalent to Polypropylene caps then they are new. They go up in ESR over the years just like others. Mylar caps start out life with an ESR higher than I like to see in caps.

... The ones I tested were at about 1/2 ohm.


At the risk of turning this into electronics for dummies, two questions.

1. What is a "good" ESR value? For example, for the electrolytic caps that I need for speakers I wish to refurb, one supplier that lists ESR lists the IMP/ESR anywhere from 40.3 to 80.5 ohms.

2. Is there any problem in replacing electrolytic with metallized polypropylene, of course using caps with the same uF and V values?

BECtoo
08-23-2006, 08:49 PM
At the risk of turning this into electronics for dummies, two questions.

1. What is a "good" ESR value? For example, for the electrolytic caps that I need for speakers I wish to refurb, one supplier that lists ESR lists the IMP/ESR anywhere from 40.3 to 80.5 ohms.

2. Is there any problem in replacing electrolytic with metallized polypropylene, of course using caps with the same uF and V values?

In all cases, for any use, as low as possible is best for ESR in a capacitor.

I like to see values of around 0.05 ohm or less in new caps. Most good new polypropylene caps test in the 0.02 ohm area.

Perhaps the spec you quoted above would be milliohms or thousandths of an ohm. A capacitor of 40 to 80 ohms would be worthless for any application I can think of.

The picture I have attached is showing a test of a good cap. You can see that the ESR is about 13 thousandths of an ohm and the capacitance is within about 1.6% of the stated value. A very good cap.

Bob Crites

BECtoo
08-23-2006, 09:09 PM
Oops, missed answering the question about substituting polypropylene caps for electrolytics. That is a good question too.

Ok, for every case, I would prefer to use a polpropylene in place of an electrolytic cap. In some cases, though, that is not practical. If you have a woofer roll off cap, for instance and its value is high like 68 or 100 uF, the cost and size of a polypropylene is prohibitive. Also, the job that cap is performing as a woofer roll off, is more like that of a trash can than anything else. In other words, it takes frequencies we don't want to hear out of that driver and sends them to ground. We do not listen to any music through that cap and its job then, is relatively unimportant. I would use an electrolytic there.

Bob Crites

subdermis2000
08-24-2006, 05:34 PM
Thanks for the guidance Bob.

Now I'm off to source caps. So far Solen looks about the best right now.

bowtie427ss
08-27-2006, 11:17 AM
If i might add my two cents worth here, you cannot go wrong with the Solens, i swear by them in all my Altec 2 way networks.

I'd just like to add a point that i haven't seen mentioned and that is in regard to handling of your new caps. Wether it's an electrolytic, poly, or film and foil, a capacitor is a hermetically sealed device. When the seal is compromized, it threatens both the ESR and uF value of the cap, and degradation begins immediately upon the seal being broken. The main point to be concerned with is where the leads exit the cap body. It's a good idea to avoid applying much stress at that point and i've seen posters on other threads recommend using hemostats or locking needlenose pliers to hold the leads while bending, soldering, or otherwise terminating those leads. Some of the larger solens get rather heavy, and i like to add a small amount of epoxy to reinforce that area where the lead exits the cap body.

I have also learned to always test every cap before installation in a circuit. Capacitor makers also make mistakes and have bad days too!

Just my two cents worth.

FalconEddy
08-27-2006, 07:40 PM
The following question is in regards to use with vintage Jensen speakers, circa 1962. I'll be using values of 33uF to 35uF, and 4uF.

Out of curiousity, has anyone used Axon (True Caps), Dayton (DMPC or PMPC), or Solen (PA or PB) in a standard 1st order (6dB) filter configuration for a 3 way application; and bypassed them with .1uF Sonicap Gen II's ???

My main concern is about poor/high ESR levels on the main caps. I'm not too worried about the Gen II's since their ESR is generally excellent.

I prefer not to buy $$$ of caps simply for testing purposes and see how they all stack up.

. . Falcon

BECtoo
08-27-2006, 09:28 PM
Dayton or Solen metalized polypropylene are both good caps with good ESR and test good and well inside their tolerance on capacitance. I haven't tested the Axon caps.

Bypassing the caps in a crossover is a totally meaningless exercise. Just put the value into a capacitive reactance formula and look at the impedance at audio frequencies of the 0.1 uF cap. The 0.1uF cap would have an impedance of 160 ohms at 10 Khz and 80 ohms at 20 Khz. Its effect would in my opinion be inaudible in any crossover circuit.

Bob Crites

Deang
09-03-2006, 06:26 PM
http://ldsg.snippets.org/appdx-ec.php3#CAPS

"Whether it's an electrolytic, poly, or film and foil, a capacitor is a hermetically sealed device."

Most caps are unprotected. The epoxy end caps provide moisture resistance only. To be hermetically sealed, a cap must be sealed in metal or glass.

"Electrolytics also have an ESR about equivalent to Polypropylene caps then they are new."

http://my.execpc.com/~endlr/esr.html

In all cases, for any use, as low as possible is best for ESR in a capacitor.

Not if you want to maintain the original voicing of the speaker.:)

quietlymknnoise
09-03-2006, 06:41 PM
Say Hey Y'all I got some (4) Kenwood KL-7070's (US KL-888A) and 2 Kl-777D and 2 KL-888D. Who can tell me if they need recap the crossovers? The 7070 I have had for 34 years and sound great on my QX-949. The others just recieved from greatfull sellers on Ebay and have not connected to my other QX-949 in the bedroom. I am hoping for some input on this. I got my secound QX-949 from Cableguy, off the Ebay site. I gave him a hard time because he had not tested on 4CH. I have he even through he did not know how to change it. Powers over all of us meant it to be perfect and it was. So, I praise Cableguy for being so kind in his responses to me.
This is a great site for us Audio Lovers.

Deang
09-03-2006, 07:03 PM
Probably built with electrolytics -- undoubtably past the end of their life cycle. Get into them, the values are probably stamped on the caps. You can find nice electrolytics here:

http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=72

You can try some nice polypropylenes to see what you think -- I tried it with some Old Advents and the top sounded too hot.

FalconEddy
09-04-2006, 04:45 PM
I finally got the 3-way Jensens recapped using a 1st order high pass method (with bypassing).

40µF (bypassed with .47µF film/foil) for the 8" mids, and 4µF (bypassed with .10µF film/foil) for the 3-1/2" tweeters.

Some of the old caps were off nearly 40%, which really manipulated the sound for the worse.

Thankfully, the recap put both cabinets back into a very similar audio spectrum; and properly dialed in the crossover points. No large humps or valleys.

What a pleasure it is to listen to these now after the tweeter x-over points aren't too low by a half octave; and the mid crossover points aren't too high by nearly a full octave!

After the break-in period they should be spectacular.

. . Falcon

Whaleman
11-06-2006, 11:18 AM
I have a pair of late 70s Pioneer CS-99A speakers. They have 6 drivers per box, the very top highs are not there, it has the original caps and I am sure the drivers are not blown. This is something I will be doing soon to recover the highs.

doctorbongo
11-06-2006, 02:23 PM
I want to start updating/upgrading some of the internals (which probably will help the sound a lot more than externals) of my speakers, and particularly my amp. I would prefer to get all of the components at once, then do the work as time permits. Is there a short list of the best places to get the electronic bits and pieces?

Whaleman
11-06-2006, 02:24 PM
I like both of these www.partsexpress.com and www.digikey.com. I have great experience with both.

doctorbongo
11-07-2006, 12:41 AM
Thanks, Whaleman. I have a lot to learn. Like, oh, about everything....

dc270
11-11-2006, 03:05 PM
Howdy --

Been searching AK and reading old threads about recapping speakers. This was a good one: http://audiokarma.org/forums/showthread.php?t=74979&highlight=recapping+speakers.

My question however isn't answered in any of the posts. At what point does a speaker need to be re-capped? How many years after original purchase? How long in storage without any use before it's time to re-cap? Do the caps last longer if the speaker hasn't been played, or if it's been in constant use?

Thanks for the help!

I rebuild and retrofit a lot of 20+ year old speakers. I always recap the networks with newer poly caps and sometimes with Solens or Wonder caps for the high end is fairly cheap insurance. In the tweeter and mid circuts they make a noticable audible improvement over electrolutic types. I also recomend using a "bypass" cap with the tweeter cap to help clean up the upper harmonics. That is a low value (like a .22 ufd poly or mylar) wired in parallel with the tweeter cap. It's an old JBL trick I learned.
Old "lytic" type caps can just dry out from age, used or not. As for the caps used in the bass sections, I still replace the large values with electrolytic types for sensible cost saving and still good performance. 10% is common varience but 5% or less is best
DC

jblmar
11-11-2006, 03:16 PM
I can only speak for myself, but I feel it's best to recap any piece of gear after 20 years. I usually recap when the component needs repair for other than capicator failure. The overall sound difference is very noticeable. Cleaner and more open.

Ron

lorne
11-19-2006, 09:16 AM
I've recapped speakers that have ranged from 15 to 35 years old using either polypropylene, Mylar or a mixture of both. In each case the difference was an astonishing improvement.

I would change out X-over electrolytics that are 10 to 15 years old. I could be blowing hot air, but this opinion is based on reports I have read about the optimum life of the electrolytic paste, as well as the effectiveness I have witnessed. Long dormant periods may be more harmful than than regularly applied current. Of course, if the owner is satisfied with something less than what the optimum may be allowing in performance, the speakers should play on for decades, as we have all experienced.

If you have a pair of older speakers you care about, I'd encourage you to recap now as opposed to waiting. Mylar caps are a good way to start — not too expensive, readily available and highly effective. Polypropes can scare you off due to their price and keep you waiting when you could be reaping the sonic benefits. Bennic brand (China) is a decent, affordable poly that has made a vast improvement in my latest project.

Some of these cap change outs may SEEM expensive, but when I go to the sound rooms and hear the shiny new products costing hundreds or thousands, I come away confirmed that fresh capacitors can make a pair of vintage speakers a brilliant opportunity. With tired caps they are just another old speaker — even really good ones!

Whaleman
11-20-2006, 08:26 PM
As soon as I am done with my receivers, I will recap my Pioneer CS-99As late 70s speakers. They sound quite dull and yet are in mint cond. The super high tweeters barely play at all. Do you recommed using mylar caps instead of electrolytics? I was just going to match what is in there already with new.

dc270
11-20-2006, 08:33 PM
DEFINATELY use the mylars or better poly, Parts Express carry Solens and they are pretty good- Wonder Caps being even better!
DC

lorne
11-27-2006, 11:09 PM
Do you recommed using mylar caps instead of electrolytics?Go with dc270's advice. If the electrolytics were the original type, replacing them with plastic caps will very likely change the way they sound. The chances are, if they are good speakers, the change will be for the better IMHO. There are a few enthusiasts who will not go to plastic caps for fear of changing the "voicing". It is one of those proverbial, old saws. Sometimes it takes some ingenuity to install the new caps because very likely they will be physically larger — sometimes a lot larger.

Mylar or Poly, this brand or that one? My two cents: go to Elliott Sound Products and read his research and opinion on caps. It may temper your bloodlust for outrageously costly caps. It is easy to spend hundreds of dollars recapping a 3-way design.

In my last speaker overhaul I used a mixture of Acro and Bennic polys as well as off-the-shelf Mitsubishi Mylar or polyester. The results were a transformational. I mean, it was not subtle. Other projects have yeilded similar results, including changeouts that used only polyester film caps.

Just get some plastic caps that you can afford and try them. They are much more suited for the purpose at hand than the electrolytic type.

Whaleman
11-28-2006, 10:21 AM
Thanks Lorne, what kind of new characteristic did the sound take? My CS-99As sound quite dull, so anything will be an improvement.

lorne
11-28-2006, 07:56 PM
Whaleman wrote:Thanks Lorne, what kind of new characteristic did the sound take? My CS-99As sound quite dull, so anything will be an improvement. Three separate cases. You should keep in mind some alterations that I made to the circuits in two of them:

Tannoy IIILZ (a sealed box, bookshelf design) with a 10 inch, Monitor Gold dual concentric driver: The original sound was pleasant and even articulate, but it lacked punch and bottom end. They sounded better when driven hard, and I knew that one side was dragging its feet. The gain and energy switches did not seem to provide any solutions in their operation. So, I replaced all the original electrolytics with common 5% Marcon polyester film caps. I had to wire them in parallel to produce exact replacement values. What I took to be the "polite British sound" of apocryphal reputation vanished. They were still euphonic and pleasant, but they now had a more distinct, dynamic range. They became more useful for a greater range of musical genres. The bottom end did not extend very much, but what was there blossomed. Low level, near-field listening became a late night pleasure. There was a whole world of detail that was not there before. I deleted the gain circuits, and I wired the network for 'flat'.

Pioneer CS-655 — a very nice Japanese, domestic, 3-way speaker model using coniferous ply, sealed boxes. I used the Mitsubishi Mylar or polyester film caps and made a piggyback circuit board for them. I deleted the gain pots (I wish I had left them in). Then I substituted R's for the pots as they would have been seen in 'flat' setting. The results were not as dramatic as in the case of the Tannoys. Perhaps the original caps were not as tired. But then, unlike your CS-99a’s and my old Tannoys, there was NOTHING dull about them to start with. Nevertheless, after recapping there was a bit more detail, and a bit richer bottom end — a worthwhile effort and worth the peace of mind.

Sansui SP-G88 — Three way using carbon fibre woofs and mids with a titanium driver. Astonishing improvement. Before recapping, this speaker was very impressive at extremely loud levels — I mean realistic night club dance mix wake up the neighbours dog howling antisocial mayhem — something I rarely do, and only when “she who must be obeyed” is outta town. That being said, they were otherwise boring and OK for running the family TV/DVD complex. Then one day I decided to recap them in stages. As I progressively changed out each cap, the sound got better and better. Now they are powerful and yet delicate. Detail has blossomed. I now hear tonal textures that were not obvious before — tonal texture such as the sound of a resined bow on strings, or the character of a Spanish guitar string. The human voice has become much more intimate. The bottom end has filled out and extended. Percussion has gained in tonal character. (I hate hearing just wacks and thuds). The sound stage has improved a lot too. These speakers have transformed into convincing and realistic musical instruments. There is so much more tonal character that I am experiencing the artistic intent in the music that was not available before. Very exciting. Except for a mixture of Mylar and polypropylene substitute, replacement caps, these speakers remain absolutely stock. Obviously, there was a LOT of speaker tech in there before I started.

In each exercise, I have gained something for no sustained losses.

Whaleman
12-01-2006, 08:30 PM
Thanks for your very well articulated response, I simply cannot wait to get my CS-99As recapped.

Now for matching a hard cap, do you mean for example a 220uF 50 V cap run 2 110uF 50V caps in parallel? Or maybe 2 110 uF 25V in parallel?

Thanks.

Micropassatman
12-02-2006, 12:21 AM
This is a thread I will keep on watching. I definitely want to recap my Polk RT12's and 16's soon, and maybe my S8's. I think they are all probably approaching that magic age. Mr Crites, thank you for the excellent advice. Man, it's really wierd writing that. People call me Mr. Crites all the time, too. :yes:

Not too common a name, really.:no:

lorne
12-02-2006, 03:18 AM
... do you mean for example a 220uF 50 V cap run 2 110uF 50V caps in parallel? Or maybe 2 110 uF 25V in parallel? Capacitors in parallel, where Ct is the total capacitance: Ct= C1+C2+C3 ... Cn. Each cap will see the same voltage, and its rating will remain the same as specified on the jacket. (But for future reference, be aware that the maximum voltage that can be safely applied to paralleled capacitors is limited to the lowest rated cap in the configuration).

220uF seems a really big cap value! Is the stock cap a non-polar/bipolar electrolytic? (I'm betting that it is.) If so, and if it is on the woofer, you might be OK with another electrolytic. But someone should analyse the network circuit and advise you on whether or not it would be worth stacking up film caps. I would ensure that the voltage on each cap is at least the same as the original, because AFAIK, the voltage of an electrolytic cap can be commensurate with the performance and behaviour in the circuit. (Whether you would actually “hear” mismatches is another question). I would also match brands and the cap's specific series. This will be printed on the jacket in the form of an alphabetic code or series number. I've had no experience in network substitutes or replacements in excess of 50uF.

dc270
12-02-2006, 09:26 AM
Capacitors in parallel, where Ct is the total capacitance: Ct= C1+C2+C3 ... Cn. Each cap will see the same voltage, and its rating will remain the same as specified on the jacket. (But for future reference, be aware that the maximum voltage that can be safely applied to paralleled capacitors is limited to the lowest rated cap in the configuration).

220uF seems a really big cap value! Is the stock cap a non-polar/bipolar electrolytic? (I'm betting that it is.) If so, and if it is on the woofer, you might be OK with another electrolytic. But someone should analyse the network circuit and advise you on whether or not it would be worth stacking up film caps. I would ensure that the voltage on each cap is at least the same as the original, because AFAIK, the voltage of an electrolytic cap can be commensurate with the performance and behaviour in the circuit. (Whether you would actually “hear” mismatches is another question). I would also match brands and the cap's specific series. This will be printed on the jacket in the form of an alphabetic code or series number. I've had no experience in network substitutes or replacements in excess of 50uF.


I respect your apparent authoity here. Are the tolerances cumulative if one uses caps combined to equal a given value? I would presume they would be, but then again I am asking you to be certain.

Yout thoughts on using a "bypass" capacitor as JBL uses it. IE like a .15 uf cap or so used in the upper freq. part of the xover to aquire a better transient responce.
Thanks
DC

FalconEddy
12-02-2006, 04:53 PM
I'm not sure which order filter your speaker uses, but a 220µF cap used in a first order filter application has a crossover point of:

4 ohm - 180Hz

8 ohm - 90Hz

So, how/where is this big cap actually being used?

. . Falcon

lorne
12-02-2006, 09:56 PM
I respect your apparent authority here. Are the tolerances cumulative if one uses caps combined to equal a given value? I would presume they would be, but then again I am asking you to be certain. I am neither an authority nor an engineer, so I consider my contribution here to be provisional. In other words, if one of AK's authoritative professionals or consummate hobbyists contradicts what I say with science at hand, and because this is a 'sticky', I will either edit or delete things unless otherwise directed by the moderator.:ntwrthy:

Tolerances will be arithmetic in a configuration of parallel capacitors. In other words, they will be both additive and subtractive. Electrolytic capacitors can be + 50% to minus 20% of the nominal value. Other types such as polypropylene, polyester, Mylar range from 1% to 10%. Remember that on top of this, electrolytic types are subject to much greater drift due to ageing and instability than film types.

Now, the following is my opinion culled from more hours spent trawling the knowledge of better minds and education than WAF may consider sane or healthy (slow learner?:tears:) : if one is going to parallel electrolytic caps, the best way to ensure success would be to use a capacitor tester to match specimens before installation. (I don’t own one myself). That being said, my approach would be to source a single cap of the specified/original value and refrain from using multiple caps in parallel.

As for film caps: failure to match caps may or may not have negative consequences. For one thing, specified tolerances are (apparently) conservative. And, variances may cancel each other. Furthermore, any residual variation from nominal value may not be detractive to performance in relative terms. There are just so many other factors involved. Obviously we want to be as precise as is practical, but WHERE the determinative limits lie is unpredictable for anything but a specific case, and even then problematic. If you use film caps at 1% (coded as F), 2% (G) or perhaps even (J) 5% you should at least have peace of mind. If you end up putting two or three film caps in parallel, and if you find evidence to support the prediction that a 5% variation from nominal spec will produce a 50 Hz shift, I'd look into the situation.

As for my projects, I just bunged-in what I had stocked for the purpose and then worried more about lead-length, good soldering and heat dissipation.

Your thoughts on using a "bypass" capacitor as JBL uses it. IE like a .15 uf cap or so used in the upper freq. part of the xover to aquire a better transient response.

IMHO, if the original design uses a bypass on the same type of capacitor as you will be using as a replacement, then use one. I have deleted bypass caps after substituting the original electrolytic primary cap with a film cap. In general, bypassing gets into a controversy of galactic proportion, and the science that might apply to specific instances becomes, at least for me, opaque. In the case of bypassing, you are free to experiment. The values are small, so parts will be inexpensive. And if you use heat clips on any leads to protect your primary cap, you can solder and snip with immunity.

dc270
12-02-2006, 10:39 PM
Thanks for the cap knowledge tour!
DC

lorne
12-03-2006, 12:22 AM
Perhaps I should have mentioned that 'Mylar' is Dupont Corp's name for their polyester recipe. This is why it is usually spelled with the upper case 'M' as it is a registered trademark. — cheers — Lorne

FalconEddy
12-03-2006, 07:41 AM
Nevermind, I just found a photo of the crossover network in the CS-99A. Obviously NOT 1st order filtration.

Based on the photo I saw, they appear to have a 5-way network. Is this correct???

. . Falcon

lorne
12-03-2006, 09:10 AM
FalconEddy wroteBased on the photo I saw, they appear to have a 5-way network. Is this correct??? I believe that I have read exactly that. What do you think this 220uF cap does? Do you have an URL for the network circuit — or whatever it was that you found?

amsoilman
12-08-2006, 07:10 PM
Is there anyone reliable in the Detroit area who can recap my Sansui 7500's. I don't have the time or knowledge.

Tripqzon
12-08-2006, 11:09 PM
I recapped my HPM-100's today because of what I've read over time on AK. I have to say that I'm glad I did it.

I was only able to listen for maybe 20 minutes tonight but did notice that they do sound cleaner and more life-like. I'll be able to tell more as time goes on.

I used Solen for the 3uf and 4.4uf replacemants and Auricap for the 0.15uf cap. I also replaced the 10ohm wirewound resistor with a Mills non-inductive resistor. I was able to do both speakers for just under $35.00 with shipping. That's not a bad price imo to do both speakers. All parts purchased from Parts Express.

Paul

phaedrus
12-08-2006, 11:29 PM
I've found this thread quite interesting but need some additional assistance.

I'm looking at re-capping some Infinity QLS'. For the Watkins woofers, they use a couple of big non-polar electrolytics of pretty high value - 1100 mf and 1400 mf. I'm having trouble locating anything in that size.

Does anyone have any ideas for sourcing these?

Thanks,

David

lorne
12-09-2006, 07:44 AM
Hi Phaedrus: I tried to help you by fishing through my (crude) database that includes Japanese sources. Sorry — I can't hit the nail head exactly, but here is what I found:

Toshin Kogyo Co. Ldt [TK]. (Toshin Industries) has a Bi-Polar radial series — 'BPUE' — that ranges from 6.3 Volts to 63 Volts, and from 0.1 uF to 2,200 uF. This series is not designated as audio type specific, but it IS specified as 'long life'. I do not know if there is much of this supply in the USA or where ever you are. TK is fairly common here in Japan, but I only ever see their standard series in local parts bins.

The Nichicon Muse 'ES' series ranges from 6.3 to 25 Volts in 1000uF. There are other capacitance values that range up to 50 volts.

A company called Chokes Unlimited lists an 'EC' series of caps — don't know the maker — which go up to 800uF at 100 Volts. See http://www.chokes.com/capec.htm

I have never made a cap bank of N.P. electrolytics before, but I can't think of how it is anything different than making parallel film types. There is at least enough here to convince me that you DO have a solution. If I were you, I'd start with getting to know what the minimum voltage requirement is, and then start skulking through cap charts to see how you can make a bank/stack for each cap position. The Muse ES series would be a good place to start because they are probably the easiest to get ahold of.

phaedrus
12-09-2006, 02:07 PM
Hi Lorne,

Thanks very much for the info, some of those look like they could get me there. I'll give them a look.

Thanks again,

David

Tripqzon
12-16-2006, 10:36 PM
I recapped my HPM-100's today because of what I've read over time on AK. I have to say that I'm glad I did it.

I was only able to listen for maybe 20 minutes tonight but did notice that they do sound cleaner and more life-like. I'll be able to tell more as time goes on.

I used Solen for the 3uf and 4.4uf replacemants and Auricap for the 0.15uf cap. I also replaced the 10ohm wirewound resistor with a Mills non-inductive resistor. I was able to do both speakers for just under $35.00 with shipping. That's not a bad price imo to do both speakers. All parts purchased from Parts Express.

Paul

Ok, I've been listening to my recapped HPM-100's daily for a week now and have to say that I'm very glad I did. The $35.00 I spent to do the pair was a minimal investment for the improvements in the sound. The edginess I'd been experiencing at certain frequencies in the midrange area, such as certain notes of piano, has smoothed out. I've also noticed a greater separation of the individual instruments of the music.

I had my brother over Friday night to do a recap of his HPM-100's and I put Diana Krall "Live In Paris" in the cdp. He commented on how good it sounded. He said there was nothing lacking in the sound and that each instrument was separated from the other instruments.

His comments made me realize that it wasn't just me wanting to believe that a recap would make a difference, but that it actually did make a difference. And it didn't cost me an arm and a leg to do it.

If you have older speakers and are thinking about a recap, stop thinking about it and do it. You won't regret it.

See 4 posts up to see which caps I used.

Paul

lorne
12-17-2006, 02:30 AM
Really glad it worked out for you — and for such a low cost. When you start replacing larger values the cost definitely goes up.

MikeCh
12-27-2006, 01:10 PM
Just thought I'd post some info from a recent conversation I had with my Dad who is an engineer and shares many of the same sentiments as others here....get the best caps you can find and/or afford.

In my instance, I'm wanting to recap a pair of older Genesis Physics I's. A very simple crossover consisting of one 10uf/50v electrolytic. According to him, the reason most electrolytic's go bad when used in cross-over designs is that because no DC voltage is being applied regularly, they lose their polarization over time....in as little as five years without this DC application.

Another thing he shared with me is that in my case, with the need for a 10uf capacitor, he said that if I were to wire two 20uf in series that it should utlimately give longer life performance. Why, I'm not sure but I'm gonna do it that way.

Mike

dc270
12-27-2006, 01:57 PM
You might also ask him about the use of a "by-pass" (.015uF or so) capacitor in the network as JBL used it succesfuly. It was suppsed to allow the unltra high freq (+15k) to pass more easily to the tweeter instead of trying to push it all through one big cap. Good info on your part too
DC

lorne
12-27-2006, 10:26 PM
MikeCh wrote:According to him, the reason most electrolytic's go bad when used in cross-over designs is that because no DC voltage is being applied regularly, they lose their polarization over time....in as little as five years without this DC application. Certainly a vital point well taken. Thanks for the report.

I have a request — a favor to ask. Can you ask your father about electroytic capacitors in general — that is caps as they are used in DC environments? What is the minimum voltage required to keep the capacitor healthy and functioning at optimum throughout its intended service life? For example, given a 50 volt capacitor, what would a minimum DC voltage have to be in order to maintain the health of the cap? Does the required voltage vary in some way in direct relation to the rated DCV of the cap or it's capacitance value.

This should perhaps be another thread, but considering how scarce and allusive this information seems to be, it may be the time and place to ask. If this does develope into something larger, I'll consider moving to another thread. Thanks in advance to both you and your Dad for any considered reply.

MikeCh
12-28-2006, 03:30 PM
Hi guys,

I asked my Dad to clarify and since I'm a long way from being or understanding engineer-stuff, I'm posting his responses verbatim so as not to miss details.....this is gonna be long :D

--------
From DC270:
"You might also ask him about the use of a "by-pass" (.015uF or so) capacitor in the network as JBL used it succesfuly. It was suppsed to allow the unltra high freq (+15k) to pass more easily to the tweeter instead of trying to push it all through one big cap."


The short answer is yes. All electrolytic caps of any size have some inherent inductance as well. As the frequency goes higher, it is possible that the capacitor will actually pass thru resonance and become inductive. Generally, if good high quality caps are used, the resonant frequency will be high enough (for audio frequencies up to 20-25kHz) that is not an issue. If there is concern, bypassing the electrolytic with a 0.1uf or so cap will ensure that very high frequencies will still get to the tweeter as they should.
--------

--------
From lorne:
"I have a request - a favor to ask. Can you ask your father about electroytic capacitors in general - that is caps as they are used in DC environments? What is the minimum voltage required to keep the capacitor healthy and functioning at optimum throughout its intended service life? For example, given a 50 volt capacitor, what would a minimum DC voltage have to be in order to maintain the health of the cap? Does the required voltage vary in some way in direct relation to the rated DCV of the cap or it's capacitance value."


When used in an application where DC is applied, it is usually best to have the voltage rating for the capacitor not more than about 1.5 times the applied DC. There are a couple of reasons for this. (1) The voltage rating of the capacitor is set by the thickness of the dielectric and by the original polarizing voltage at the time of manufacturer. (2) As a capacitor ages the dielectric tends to "adjust" to the applied DC potential. For example, a capacitor that is rated at 50 vdc at the time of manufacturer is used with a DC potential of 15 vdc for an extended period of time. The capacitor will tend to age to a new breakdown potential that is somewhat more than 15 vdc but way below the 50vdc original rating. It might breakdown at around 25vdc. To maintain the original 50vdc rating the capacitor will need to be operated typically within 20% or so of the original rating.

All electrolytic capacitors are "pre-polarized" when new. As the capacitor ages, depending on the quality of the dielectric and application, the dielectric slowly loses its ability to remain polarized. The typical shelf life of good quality caps is measured in several years. If they are used in an application where little or no polarizing voltage is applied, there is nothing to prevent the natural depolarizing. As the caps depolarize, the breakdown voltage drops. Using a cap where just AC is being passed can accelerate the process. If the AC was perfectly symmetrical there would be no contribution to the depolarizing function other than natural aging. However, in the typical audio application the audio is highly asymmetrical. This can result in reverse polarizing currents that further accelerate the demise of the dielectric.
Putting two capacitors back to back, either negative to negative or positive to positive, especially if you also include a pair of back to back diodes across the caps to direct the current flow, can sometimes slow the deterioration. Usually the easiest thing to do is just make sure proper DC voltage is applied or replace the caps from time to time. Years ago, it was common to use oil filled caps. These are not polarity sensitive and don't change with time. Now that oil filled caps are getting harder to find that is sometimes not an option. Once in a while you can find a motor start or run capacitor of the correct value. Those are oil filled but rather costly.

--------

I hope this helps!

Mike

lorne
12-28-2006, 09:14 PM
Thanks Mike! And please extend our gratitude and appreciation to your father. Cheers! Lorne :thmbsp:

BECtoo
12-28-2006, 09:17 PM
Ok, there is typically no DC at all in a crossover, so polarized electrolytics should not be used since they depend on DC to form or re-form the electrolytic. If you must use electrolytics in a crossover, use non-polarized electrolytics. They are sometimes the only practical cap for some very large values of caps usually used in woofer roll-off circuits.

One place to get the non-polarized electrolytics is Parts Express.

http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=72

Bob Crites

lorne
12-29-2006, 12:48 AM
BECtoo wrote:They are sometimes the only practical cap for some very large values of caps usually used in woofer roll-off circuits.
Some questions,:yes: OK?

* For example, HOW large? I cannot remember seeing X-over caps any larger than 47uF.

* Is there any advantage to using film caps in the woofer roll-off circuit?

* Is there a simple way to identify a roll-off circuit on an exposed X-over network. And if not and assuming I have a schematic (or produce one by reverse process) ...

* ... what do I look for on the schematic?

I hope that this does nt put you on the spot :smoke:

BECtoo
12-29-2006, 09:38 AM
BECtoo wrote:
Some questions,:yes: OK?

* For example, HOW large? I cannot remember seeing X-over caps any larger than 47uF.

* Is there any advantage to using film caps in the woofer roll-off circuit?

* Is there a simple way to identify a roll-off circuit on an exposed X-over network. And if not and assuming I have a schematic (or produce one by reverse process) ...

* ... what do I look for on the schematic?

I hope that this does nt put you on the spot :smoke:


I don't think there is an "audible" advantage using a good film cap in a woofer roll-off circuit. Two problems using a polypropylene cap for the 47 uF you mention are size and cost. The 47 uF cap as an electrolytic is about a buck where the 47 uF as a Solen poly is about $13.00. The poly cap is also about ten times as big (physically) as the non-polorized electrolytic. Some of the crossovers I build or rebuild use as much as 136 uF for the woofer roll-off caps and there is not enough room to use the larger poly caps. But, if I could find a real benefit audibly to using the larger more expensive caps in that circuit, I would do it.

As far as the subject of bypassing the large caps with a tiny value of capcitance (.1 uF or less) doing anything at all in a crossover, someone would have to give me a theory about why that should be done before I could go for that one. I just can't see that one at all.

The 68 uF cap in the attached schematic is the woofer roll off cap.

Bob Crites

mlhm5
12-31-2006, 11:15 PM
http://www.humblehomemadehifi.com/Cap.html

Pyrrho
01-06-2007, 08:46 PM
And now for a different perspective. I respectfully disagree with those who advocate replacing parts without knowing if they have gone bad. Sure, some people will replace something that has gone bad that way, but a lot of things that haven't gone bad get replaced, too. And afterwards, there is a tendency to think that things sound better, because one listens closely to observe any difference, so one notices more detail. Of course you will notice more detail if you listen closely and pay attention! But without properly putting the old capacitors back in and switching back and forth, listening to each carefully, you will not have a fair test at all.

Of course, if the capacitors have gone bad, you should replace them. I have done that in crossovers myself. And that really does improve the sound.

lorne
01-07-2007, 09:18 PM
Hi Pyrrho: I am respectful of your opinion and would agree with you up to a point. Replacing parts with similar ones is not likely to produce gains. And the "psycho-audio" factor is something to be seriously considered — a metaphorical placebo effect. But I would submit some things that have been discussed above remain:

(a) In something less than a decade, bipolar/ non-polarized electrolytic capacitors having virtually no DC voltage applied to them will be in a state that is less than their original or optimal state.

(b) In many parts of the Xover circuit, substitution of electrolytic capacitors with film types will change the sound of the speaker. In most cases this will offer benefits in sonic performance.

(c) This is a subjective point: in some cases these benefits are so dramatic, and they may be so astonishing, that we may refer to them collectively as a transformation that exceeds anything we might otherwise suspect as illusional.

Of course you are right about a fair test. This can actually be done quite easily in many cases if the owner is willing to move the Xover network outside of the cabinet. But it will be necessary to construct a separate network containing the substituted parts. This can allow the owner to conduct a blind A/B test with the help of an assistant. I have moved Xover networks to external positions, but I have not gone to the trouble of duplicating them for testing purposes.

Pyrrho
01-08-2007, 09:42 AM
Hi Pyrrho: I am respectful of your opinion and would agree with you up to a point. Replacing parts with similar ones is not likely to produce gains. And the "psycho-audio" factor is something to be seriously considered — a metaphorical placebo effect. But I would submit some things that have been discussed above remain:

(a) In something less than a decade, bipolar/ non-polarized electrolytic capacitors having virtually no DC voltage applied to them will be in a state that is less than their original or optimal state.
...

They don't have to be perfect to still perform audibly identical to perfect ones. If they are reducing the signal to one of the drivers significantly, this will be audible. And if they have altered the crossover frequency significantly, such that one is worried about damage to drivers (as has been mentioned by others in this thread), this, too, will be audible, as speakers tend to audibly distort before they are damaged. If one hears a problem, then one should fix it. But if there is no audible problem, then it really doesn't matter, right? I personally own two pairs of speakers that are about 35 years old, which have all original capacitors, and I have noticed no problems. However, over a decade ago, I had to replace the capacitors in a pair of speakers from that same vintage, because they were causing audible problems. (In other words, I replaced capacitors that were "only" about 25 years old.) The lifespan of capacitors is variable, depending upon the original construction, and, of course, what has happened to them since then. Regardless of how old or new something is, if it is malfunctioning, it should be repaired. If it is not malfunctioning, "repairing" it is a waste of resources.

Of course, one may wish to modify someone else's design, which may be done at any time. But before doing that, one should really know what one is doing.

Now, obviously, since I have not made an identical crossover with new capacitors, I cannot be certain that there would be no audible difference if I were to replace the capacitors in the speakers. But on the other hand, I cannot be certain that the woofers are performing exactly to spec, or the tweeters, etc., either, without doing some proper testing of them. But no one is advocating that I replace these simply because they are old. That is what I am objecting to doing: Replacing things because they are old rather than replacing them because they are malfunctioning. Sure, capacitors are more likely to go bad with age (forgetting, of course, about foam surrounds on some speakers...) than other components, but they need not be replaced until they have actually gone sufficiently bad to cause an audible problem.

mike luthera
01-09-2007, 07:11 PM
Ok,
I have a few questions also. I have a pair of Sansui SP-X9000 speakers. One of the two when i change the switch between clear/normal/and soft theres barely any change in the output. Not that it sounds bad because they dont. Would recaping these be worth my effort?
Also, I'm confused on what type of caps to replace them with. I'd like to keep as close to the originals as possible. They look like radial electrolytics but i see no + or - marked on them. Theres 4 caps total per speaker 2 - 50v 3.3uf, 1 - 50v 15uf, 1 - 50v .47uf. any help would be great.

dc270
01-09-2007, 07:16 PM
Speaker caps are non polorized so there is no + or -. Solens make good replacements capsd as does Dayton from Parts Express

Tripqzon
01-09-2007, 07:48 PM
I've used Solen and Auricap from Parts Express with audible improvements in audio quality on speakers that are approximately 30 years old..

Paul

mike luthera
01-10-2007, 06:40 PM
Attatched is a picture of my Sansui SP-X9000 crossover. If these are not electrolytic can someone tell me what type they are? I'd like to replace them with as close to the original as possible.

Thanks

dc270
01-10-2007, 06:45 PM
Those certainly look to be electro's!
DC

william.keith
01-11-2007, 10:24 PM
I have been following this Thread with a great deal of interest. I have a pair of Klipsch Chorus I speakers that I purchased new exactly 20 years ago. They seem to sound just fine but I do not know if it would be prudent to replace some or all of the x/o components. Where/who do I go to specifically discuss possible actions I might take to ensure that the sound quality of the Chorus I speakers is the best that it can be? :scratch2:

hpsenicka
01-11-2007, 10:36 PM
I have been following this Thread with a great deal of interest. I have a pair of Klipsch Chorus I speakers that I purchased new exactly 20 years ago. They seem to sound just fine but I do not know if it would be prudent to replace some or all of the x/o components. Where/who do I go to specifically discuss possible actions I might take to ensure that the sound quality of the Chorus I speakers is the best that it can be? :scratch2:

The Klipsch forum here on AK might be a good place to ask questions specific to Klipsch products.

epoch5
02-15-2007, 10:10 AM
I have 4 JBL L100s that I just recaped, well worth the time and expense.:yes: :music:

Whaleman
02-15-2007, 12:59 PM
How is the sound different now? Still wondering if it is worth it on my CS-99A? Or sell them and let someone else do it...

Tripqzon
02-15-2007, 04:36 PM
I'd also like to know how the sound changed.

Thanks,
Paul

MitsuMan
02-15-2007, 04:54 PM
I'd also like to know how the sound changed.

Thanks,
Paul

Certainly it depends on a number of factors, but to give you a "general" answer to that question here's my take.

I recently recapped some Mitsubishi 2-way monitors that I have owned since new in 1978. They were sounding very midrange-heavy, lacking in high frequency detail, and the bass was very thin. I found myself trying to compensate with tone controls, something I'd NEVER done in the past.

A fellow Aker told me which caps to order (Solen) and he essentially did the recap for me. After getting the speakers back, I called him immediately and said the only word that came to mind to describe the difference was "Dramatic."

I had lived with these speakers for 28 years. After having them recapped, I had my old friends back. The bass was extended and deep, (the woofers weren't trying to reproduce mid and high frequencies they weren't designed to reproduce any longer) The highs were "tinkly" again, in other words transparent and well-defined. The mids no longer were gnawing my ears off, and were producing presence, not a grating sound like you get when you cup your ears with your hands and listen.

I hope that helps in some way. :thmbsp:

MikeCh
02-15-2007, 07:07 PM
How is the sound different now? Still wondering if it is worth it on my CS-99A? Or sell them and let someone else do it...

I have to say I'm puzzled with you're response. Your signature below your username says "DIYer All the Way" and since re-capping is really quite a simple exercise......though I'm not familiar with the CS-99A's you refer to. Are those extra-special-tough or something?

Just wonderin.

Mike

meggy
02-22-2007, 10:33 PM
http://i146.photobucket.com/albums/r279/meggy_030/leakycaps.jpg


From JBL Century L-100's.

Anyone got any specific recommendations?
Thanks.

lorne
02-23-2007, 07:33 AM
Hi meggy: Is this a troll? Are you serious!?

These caps are 25-30+ years old! And I have a vague suspicion that the actual design and engineering of the caps are older than that. So you are indeed in need of a simple change out.

I'm not an archivist sort of restorer nerd, so I don't recommend electrolytic caps. We’ve come a long way, and the drivers can be much better employed with today’s more appropriate parts.

It appears that the caps are glued onto that ... er ... board. So the simplest way to change them out is to chisel away and peel them off. Gob some polypropylene or Mylar caps of the same capacitance onto the press-board with some hot glue and a $12 glue gun. Ride into Dodge!

You could also get some breadboard, a wafer of plain phenolic, or a rectangle of 1/4 inch ply. Drill the needed holes, and then glue or tie the new parts on with plastic cinch-ties. Hard wire the bits to replicate the original circuit with updated parts. Alternatively, with a chunk of breadboard you could solder the caps in place and jump the wires to the caps to duplicate the circuit. If the caps are very heavy, you may end up having to either tie down or 'peg' them with glue to keep stress off of the solder joints.

Your choice, but however you do it, I predict that you are in for a pleasant surprise! I would LOVE to have these speakers to work on. LET US KNOW! Enjoy the music!

Whaleman
02-23-2007, 12:27 PM
I have to say I'm puzzled with you're response. Your signature below your username says "DIYer All the Way" and ...

You haven't seen a CS-99A crossover yet, everything is extra glued in. Probably will take a hammer to get the old caps out. Maybe not worth my effort...

meggy
02-23-2007, 01:30 PM
Hi meggy: Is this a troll? Are you serious!?

Completely serious. Project for the week-end. Have 4 crossovers to rebuild. They all look about the same.

Putting in Solens caps (8's & 3's), new L-pads, and thinking about adding a .51 OHM resistor for tweeter protection. I see different thoughts on that (adding a resistor) over at audioheritage, but I don't see how it could hurt.

While I'm in there, probably switch out the speaker posts, if I have enough of them.

Last weird thing is the question on the woofer polarity. Supposedly it's opposite of the mid & tweeter for some JBL reason??? I think I'll just put that back as is.

Insulation. Hmmm. I wonder what thick new uniform sized high-tech insull would do. It's all kind of ratted in there now.

Any other ideas would be greatly appreciated. I can't find much in old AK threads re: JBL L-100 Century crossovers.

powerman
02-23-2007, 10:10 PM
You haven't seen a CS-99A crossover yet, everything is extra glued in. Probably will take a hammer to get the old caps out. Maybe not worth my effort...
Here is a tough one
http://dmbshare.org/pictures/20070111/1.jpg
http://dmbshare.org/pictures/20070111/2.jpg
http://dmbshare.org/pictures/20070111/3.jpg
http://dmbshare.org/pictures/20070111/4.jpg

lorne
02-23-2007, 11:27 PM
Here is a tough one In other words, you really need the schematic. This is incredible. Did it actually come like this from the factory?

powerman
02-24-2007, 12:49 AM
This is a JBL 3143 xover for the 4343 monitors. Hot plate used to heat old
hot melt glue. All caps and some resistors replaced. Rebuilt 4 of them and
are the hardest ones in the series. 4 way tight fit

darko
02-26-2007, 08:06 PM
Have replaced the Caps at Kenwood's KL-660s.
ONE AFTER OTHER, for Compare !

Its a huge Difference in most Frequencies. I mixed different Farad-Values together, to become the exact Value. Soldered all in parallel, of course !

This Weekend, I get some Marantz Speakers.
After One Speaker was Re-capped, I puch the MONO Switch and
have listen all the Night long.

Guys. recap Your old Favorite Speakers and listen the Difference!


Good Work!

Darko

HamBone77
03-05-2007, 05:00 PM
Most definately worth the effort. Although the advents have a fairly simple crossover. Used Daytons and like others have said both bass and highs more defined clarity.

As far as other components I tend to follow the school of "if it ain't broke don't fix it". I don't have the technical background to offer an educated opinion. However, most of the people professing engineering backgrounds I have talked to pretty much indicate that in most crossovers the capacitors are subject to greater changes in value overtime. There by justifying replacing them at 20 years of age, certainly at 25.

Peace,
HB :music:

hpsenicka
03-08-2007, 02:20 PM
I've long been an advocate for recapping vintage gear as well as speaker crossovers.

Having just aquired a DMM capable of measuring capacitance, I thought it would be fun to check the values on a pair of crossover caps removed from some Minimus 7 speakers.

The original caps are spec'd at 4.7uf, but they actually measured at 6.06 uf and 6.43 uf respectively. For comparison purposes, a pair of new Dayton 5% caps I have here measure at 4.71 uf.

What is perhaps a bit surprising here (at least to me...) is that there has been considerable drift from the original capacitor values, even though I believe they are likely less than 20 years old! This suggests that recapping even relatively new (i.e. more than 10 years old) speakers may be worthwhile... .especially with the high quality caps available today.

Brian4561
03-08-2007, 02:27 PM
http://i146.photobucket.com/albums/r279/meggy_030/leakycaps.jpg


From JBL Century L-100's.

Anyone got any specific recommendations?
Thanks.


Were it me, I'd leave the old ones in, just clip the wires. If you have the room, getting them out entirely could be more of a PITA than it is worth.

Bauhausler
03-13-2007, 10:12 PM
I'm new to this thread. Today I had to pop the terminal cup off of a Celestion 5 to tighten a loose terminal. I ended up putting big toothed washers on both terminals on both speakers so tha twouldn't happen again. I hate a loose terminal. The tweeter pass cap was a 4.7uf Bennic NP electro. I tossed them and glued in some generic mylar box caps in their place. Soldered 'em in and screwed it back together. Honestly, I don't know if this actually makes a difference, but the speakers are at least 15 years old and no electrolytic ever made equaled a mylar of the same value at high frequencies, especially after a decade and a half. I just toss the electrolytics as a matter of course every chance I get. I left in the NPE parallel cap on the woofer, not having a 6uf NPE handy. That should probably go as well. If it loses capacitance or gains resistance with age, the woofer's passband will rise into the tweeter's and might cause audible effects in the overlap range.

In my considerable experience with vintage speakers, a lot of what we consider the 'mellow' sound of vintage 2-ways is out of spec tweeter pass caps. They're mellow until the crossover is performing the way the designer intended, then they brighten up and sound new again. I say 2-ways because a tweeter with a lower crossover will have a larger cap. A larger cap will be more susceptible to aging effects that would affect the treble, or so goes my thinking. I know it improved my AR3a's, KLH 7's, Large Advents, Small Advents and many others.

Any design that depends on the parasitic resistances of a capacitor for its 'voicing' is a defective design.

Come to think of it though, maybe that's the answer to an old mystery. I had a number of Unity Audio speakers when that company was operating here in MI. One of them, the Signature 3 I think, ran the woofer fullrange and had a simple tweeter crossover consisting of a 6uf cap in series with each tweeter lead, essentially 2 6uf caps in series for 3uf effective capacitance. He called a 'balanced' crossover. Bob Grost is a very smart dude and I suspected he was up to something. The series inductance of 2 6uf caps is probably 4 times that of a single 3 uf cap. That might be useful in damping a HF peak in the tweeter. Only reason I can think of that isn't complete snake oil.

MikeCh
03-20-2007, 11:57 AM
What is perhaps a bit surprising here (at least to me...) is that there has been considerable drift from the original capacitor values, even though I believe they are likely less than 20 years old! This suggests that recapping even relatively new (i.e. more than 10 years old) speakers may be worthwhile... .especially with the high quality caps available today.

Per an early post:

"As the capacitor ages, depending on the quality of the dielectric and application, the dielectric slowly loses its ability to remain polarized. The typical shelf life of good quality caps is measured in several years. If they are used in an application where little or no polarizing voltage is applied, there is nothing to prevent the natural depolarizing."

It's unfortunate that they don't last as long/retain their original value as we'd all like.

Mike

Tapehead47
03-28-2007, 11:09 AM
I want to recap 2 pair of JBL 4311's. The parts would be about $80 from Parts Express. Has anyone out there have an idea how much it would cost to have it done for me?

After looking at many of the pix on this thread, I'm a little intimidated.

Rick

lorne
03-29-2007, 08:46 AM
Hi Tapehead. I don't know the speaker, so I'm not the one to give a possible number. But let's look at some stuff:

* If the original board uses electroytic capacitors, and if you are substituting film capacitors (a good idea IMHO) the new caps may not fit on the cross-over network board. If this is the case, the technician you are paying will have to construct something or add something in order to mount the caps. This will take time and money.

* Some networks are more complicated than others. In my modest experience, the time it takes to exchange network caps varies from one to the other considerabley.

* What is the rate for shop time where you are? $60.00/hr?

* If there is a DIY AKer living near you, and if you were to spring for the beer and a pizza, maybe you can get together and make an afternoon of it. You can apprentice to the technique and help the next guy down the road.

* You could also take some good digi pics and let us try and talk you through it. Make a large drawing on a big sheet of paper in order to show us what you are intending to do before you start — a schematic drawing of sorts. Digi-image the drawing and include it in your upload.

Just some suggestions ...

Tapehead47
03-29-2007, 09:03 PM
I don't know any AKers near me, but I have a Master Electrician friend who could do it. I don't think he works on speakers, but he wires all kinds of fancy things like dentist equipment, hospital gear, high-end surveylence systems, etc.

He had a great stereo years back, including a lot of Pioneer gear and HPM-100's.

I'll have to give him a call.

Thanks,
Rick

FoolForARadio
03-30-2007, 05:49 AM
I don't know what you want to stick caps in. It might be something really nice. But I have found that I can do this type of work, and I am completely not handy with tools! I should say that I am working on speakers I have bought cheap, so far, EPI 100V's and Sansui SP-100's. I bought some caps from Parts Express, a soldering station and tools (including heat sink) at Radio Shack, practiced a little bit, and went for it. It makes an audible difference to the speakers, and it's just not that hard. I take out one cap at a time and replace it, so I don't get confused. You should try it. It's very satisfying and a lot of bang for the buck!

Tapehead47
03-30-2007, 07:20 AM
Thanks, Fool...Your words are encouraging. I'm recapping 4 JBL 4311's. I repeat: I (that's me) will be doing the work.

Rick

lorne
03-31-2007, 07:09 AM
I don't know any AKers near me, but I have a Master Electrician friend who could do it. Sure, go for it. Do some searches in AK and get aquainted with what kinda caps we weld into speaker networks. Best o' luck!

RobD8870
04-04-2007, 08:06 PM
Hey Whaleman!!!!!!!!!!!!!!!! I was reading this post for this very reason. i just picked up cs-99A and Both speakers work great except my mids are gone on the one. No output at all. I checked inside. All connections look good *for as much as that is worth* but at least one cap was leaking. I will have to recap mine so if you have the list of values and where you got them that would save me a lot of time!!! Also how much? Not even sure if you have picked them up yet I was just so excited to see you had the same speaker with similiar problems......

Tapehead47
04-05-2007, 05:44 PM
I'm putting the recapping of my 4311's on hold until my birthday (July). I'm planning ahead.

Question: would you, as a loyal AKer:

A) Go to Maui for a week?

B) Vacation on Anna Maria Island, (south of Tampa) for a week?

C) Recap 4 4311's?

D) Upgrade your system?

I LOVE Anna Maria. I LOVE my speakers. I LOVE Hawaii. I'd LOVE to have an upgraded (not necessarily new) system.

So many possibilites, and plenty of time to choose.

Rick in Lutz, Fl.

lorne
04-09-2007, 07:34 AM
:beer: C) Recap 4 4311's? Stereo is only TWO speakers. Why recap 4? Save the clams and spend a day and a night in a five star hotel with a companion of your choice and room service!:banana: :tresbon: :thmbsp: :smoke: :D

The Rebel
04-15-2007, 06:43 PM
:beer: Stereo is only TWO speakers. Why recap 4? Save the clams and spend a day and a night in a five star hotel with a companion of your choice and room service!:banana: :tresbon: :thmbsp: :smoke: :D

what he said..... but for some reason I don't think you're gonna save enuff clams to get that deep in to the action. :sigh: But it sure sounds good.

This thread has already got my interest piqued by two re-cap jobs that I can't wait to get in to. HPM-100s and EPI 100s . And all this time I thought it was me. Good stuff.

Rebel

Tapehead47
04-15-2007, 06:48 PM
I'll recap two of the 4311's and compare the results to the remaining two. But I've put it off until July for various reasons.

Rick

Whaleman
04-15-2007, 07:48 PM
I just recapped the eletrolytic capacitors in both my Bose series IV equalizers, man what a big difference, very crisp highs and deeper bass. :thmbsp: :music:

hal2000
04-29-2007, 03:38 AM
I just ordered some caps for my Polk 5Bs. The schematics call for 34uf and 12uf caps. I ordered the dayton non polarized caps. I belive they are electrolytics, as the originals are. They are labled high quality and really cheap. Are these o.k. or should I have sprung for the solens, at least for the 12uf tweeter. As long as I bring my crossovers to their original specs that's fine for me.
Hal

Whaleman
04-29-2007, 04:16 PM
I got electrolytics for my CW D-7 and the SP-2500 yesterday. I did not got for the $12 each stuff, but I got the ones from Digikey. The values were easy to match but I had to go up in voltage as the lower voltage was not stocked. I plan to recap one at a time and compare it to the other side. I'll report.

Trance88
05-05-2007, 11:24 PM
What is recapping???? Is the cap that center "button" thing in the middle of the speaker?

lorne
05-06-2007, 07:38 AM
Trance88 wrote:What is recapping???? Is the cap that center "button" thing in the middle of the speaker? Some people might assume that you are trolling, but I read your post over and elected to answer you as best as I can:

Recapping refers to the removal and replacement of capacitors in an electric circuit, such as audio employs in virtually all of its commensurate components. And the term ‘recapping’ usually refers to changing-out of the electrolytic type capacitors. The other breed, which is commonly referred to as the ‘film capacitor’ type, may be subject as well. But it is the electrolytic type that receives most of the attention for very good reason

Electrolytic types are especially subject to degradation as a consequence three factors: time, temperature and engineering/production parameters. Due to physical constraints, the latter is nearly fixed. But the other two factors can be variable to a great degree. This allows for the fact that unit 'A' of the same model may see an operational life that is much longer than 'B'. Unit ‘B’ may have been operating in an environment that was simply more stressful on all the components, and electrolytic caps are often at the greatest risk in terms of longevity.

All electrolytic types have a more limited capacity for optimumal performance than do other constructions. But, they have very definite advantages, such as price and relative compactness of size.

In speakers, the much preferred type of electrolytic cap has been the non-polar type — alternately called a bi-polar capacitor. Cheaper speakers, or speakers of a certain vintage contain such capacitors. Such capacitors operate in an AC environment. This is a hazardous condition for electroytic capacitors. The electroytic paste which makes up the electrolyte in the cap is made effective by a polarized DC current. Without this environment, the optimal performance of capacitors in crossover circuits of speakers have a forshortened life expectancy. They may exhibit some effectiveness way past their useful, optimal life. And so old speakers may belt out the sound; nevertheless many users report huge benefits after substituting new caps for old. Replacing fairly decent film caps with new ones may not reveal anything like the same magnitude of change.

Many modern, quality speakers, as well as more and more pedestrian production are supplied with film type capacitors of one type or another. By definition, film type capacitors are non-polar. The health and integrity of this kind of capacitor does not require a polarized current. You can pass a sign wave through it for a very long period and it will be happy. Various advantages are available to crossover circuits that use this kind of cap. These are better explained by the more learned members who have mastered the trades. But I will say here that generaly speaking, film caps are the better substitutes for electrolytic capacitors should you find any in your work.

All that been said, it is fair to caution you that it is not unusual to find that there is not enough room on older crossover boards to mount film capacitors. They are invariabley larger than their electrolytic counterparts of the same value. Thus it is sometimes necessary to make modifications to the cross-over module in order to change cap types.

Should you attempt such a substitution, it is very important to learn and practise soldering techniques as well as the basics of consrtruction. Virtually anyone can learn how to do this if interest and effort is applied.

WARNING: Experience, effort and success in this area can lead to a serious addiction requiring professional counselling and extended rehabilitation!

Trance88
05-07-2007, 03:28 PM
Ohhhhhhh!!!!! It's the capacitors. Thank you for answering my question. I had no clue what everyone meant when they were recapping. I thought it had to do something with the actual speaker.

hal2000
05-16-2007, 02:21 PM
Just recapped my 17 year old Polk Monitor 5B speakers. I used parts express "high quality NP" electrolytics capacitors, the cheap stuff. I also put in the dayton high quality 10W resistors. The sound seems smoother and more detailed. I measured all the old stuff and it all spec'd out. My question is if the old components checked out can there still be improvement in sound or am I just hearing things. Also is 17 years old for elec. caps?

BECtoo
05-16-2007, 05:42 PM
Just recapped my 17 year old Polk Monitor 5B speakers. I used parts express "high quality NP" electrolytics capacitors, the cheap stuff. I also put in the dayton high quality 10W resistors. The sound seems smoother and more detailed. I measured all the old stuff and it all spec'd out. My question is if the old components checked out can there still be improvement in sound or am I just hearing things. Also is 17 years old for elec. caps?

Depends on what you measured when you say they "Spec'd out". Normally what is bad is ESR (Equivalent Series Resistance). That takes a special and pretty expensive meter to measure.

Bob Crites

hal2000
05-17-2007, 02:55 PM
I just measured the basics on a DMM, ohm value.

hal

flyingseagull
05-18-2007, 08:50 AM
about recapping speakers.I just recapped two pairs of vintage speakers incl. klh5's with good film caps. I used hovlands,and max caps in the klh and clarity and max caps in the other.The gain is tremendous.The klh was done in two stages. initially the original electrolytics in the mid and woofer were tested in spec. so just the hovlands were put in the tweeter. huge gain. then max caps were put in the mids and woofer. another large gain.I played these speakers in a shop against $6,500 cdn spendor s9's and stand behind the klh5's .For those unfamiliar these[1972] were designed by Kloss to compete directly with the more famous ar3a. many consider them better.
The second pair [burhoe blues] had cheap film caps already.These had improved the ancient electrolytics BUT the move to GOOD film made an enormous difference!! This is a MUST DO for those who would like to hear the best out of their quality vintage speakers!
As to cost: the max caps are available from a toronto design outfit [maxspeakers.com] at a cost e.g. of $7 for 10uf.They make all values. These caps are sensational value for money. i told the guy to submit them to the Humble Hifi cap comparison site but he does most of his business in the speaker industry and seemed noncommittal for some reason. He also designs exceptional drivers.
Those people who still insist that caps cannot make that big a difference unless they deteriorate should reconsider..The matter is indisputable, unarguable, unassailable and fully determined[did i say i felt strongly about it?]
RECAP and Fast. hope this helps fence sitters.

ka7niq
05-27-2007, 03:39 PM
I've recapped speakers that have ranged from 15 to 35 years old using either polypropylene, Mylar or a mixture of both. In each case the difference was an astonishing improvement.

I would change out X-over electrolytics that are 10 to 15 years old. I could be blowing hot air, but this opinion is based on reports I have read about the optimum life of the electrolytic paste, as well as the effectiveness I have witnessed. Long dormant periods may be more harmful than than regularly applied current. Of course, if the owner is satisfied with something less than what the optimum may be allowing in performance, the speakers should play on for decades, as we have all experienced.

If you have a pair of older speakers you care about, I'd encourage you to recap now as opposed to waiting. Mylar caps are a good way to start — not too expensive, readily available and highly effective. Polypropes can scare you off due to their price and keep you waiting when you could be reaping the sonic benefits. Bennic brand (China) is a decent, affordable poly that has made a vast improvement in my latest project.

Some of these cap change outs may SEEM expensive, but when I go to the sound rooms and hear the shiny new products costing hundreds or thousands, I come away confirmed that fresh capacitors can make a pair of vintage speakers a brilliant opportunity. With tired caps they are just another old speaker — even really good ones!
I agree on the Bennic Poly Caps.

I actually prefer them to Solens.

Every speaker I have ever put Solens in was a disappointment, and I consider them a bright sounding capacitor.

They totally ruined my Yamaha NS 200 M's, and made a Klipsch Heresy brighter too.

Upon someones advice, I simply ordered some Bennic Poly's from Madisound, slapped em in, and both speakers settled right down.

Trance88
06-25-2007, 05:20 PM
I bet my 26 year old Realistic MC-1200's could use a recap! Everything's original on them. If I do decide to repace the capacitors I should find ones that are rated the same as the old ones?

tomt
06-25-2007, 06:06 PM
http://waltjung.org/PDFs/Picking_Capacitors_1.pdf

http://waltjung.org/PDFs/Picking_Capacitors_2.pdf

avguytx
06-25-2007, 06:15 PM
I recapped my Polk SDA 1C's with the Solen PB caps along with Mills resistors over the weekend and am very pleased with the results. Maybe my ears aren't good enough to hear the difference between the Solens, Bennics, etc, but there was a major difference in the sound, staging, depth, etc...all the way around. I've used the Dayton Polys from Parts Express in other speakers with good results as well. I just wasn't ready to spend the extra $$$ on the Sonicaps, etc for my speakers. I know they are better by far but for cost effectiveness, I am happy.

Definitely an easy upgrade with phenomenal results to be had.

Starrider1
06-25-2007, 11:48 PM
Thanks for the information lorne. As someone who know's very little regarding this type of electronics your post was very helpful. Any suggestions on the best way to start learning and working on receivers and speakers or resources for reading material?

fiddlefye
07-06-2007, 08:48 PM
I just got my 1st speaker re-cap done, a pair of EPI M100's that had been sounding deathly dull for awhile. In addition to the re-cap they were re-wired with equal-length runs of good quality solid-core.

I've had a number of mods done to different components in the past year or so and felt that they were all worthwhile and some were in fact quite dramatic. Nothing I've had done to the present came even close to the improvements in the EPI's. Wow! Those speakers have never sounded like they do now at any time in their existence. The bass is huge and nicely defined, mid-range is sweet and the treble is delicate and nicely defined.

My EPI M50's are getting the same treatment now and then I'll be working my way through the collection. I'm sold, to put it lightly....

Bauhausler
07-07-2007, 04:14 PM
I just bought 8 of these from West Florida Components, from whom I have bought a lot of caps for speakers. They have a pretty good range of metalized, and NP electrolytic and a few Film/foil. These are 5uf/50V Cornell WMF series caps. They're physically large because of the foil construction. According to the datasheet they are designed to be non-inductive, which takes a more complex design and manufacturing process. 5uf is the largest size made in 50V, the lowest voltage. Technically, these should outperform ordinary metalzed caps. I measured a few of them and they're all less than 2% off value, much better than the 10% spec. The dielectric is polyester and the foil is probably alu. I buy good caps for future speaker repairs in quantity when they're available. I'll be on the lookout for more of these C-D WMF caps, as they seem very well made.

I don't know if this link will work, but here's the spec sheet:

http://www.cde.com/catalogs/WMF.pdf

bluesky
07-13-2007, 11:26 PM
Hi and thanks to all. So very informative and enlightening!!!! I'm about to recap my 4 each Sansui SP-2000s and really appreciate all your advice. SUPER THANKS TO ALL AKers!!!!!!!!!!!!!

archie2
07-28-2007, 12:42 PM
Very interesting and informative thread. I have previously recapped and refoamed a pair of Original Advents and the sound seemed to improve over time. I had not heard them prior to recapping and refoaming so I have no comparison. Yesterday I recapped and refoamed a pair of New Large Advents, again not having heard them prior (bought 2 pair Original and 1 pair New Large Advents with shredded surrounds). I know that surrounds need a break in period in order to become pliable but I didn't think caps did. From what I've read on break in periods for caps there is an argument on both sides. Because I did recapping and refoaming at the same time I won't be able to tell from where any improvement comes.

lorne
08-15-2007, 02:49 AM
Hi Starrider; sorry for late reply , I have not been around AK for awhile due to work stuff.Any suggestions on the best way to start learning and working on receivers and speakers or resources for reading material?There is a short-list of books recommended by AK people. They range from general theory to diagnosis and repair. I am always intending to order the books, but I always forget where I parked the list. If I find it, I’ll post the info in a new thread. In the meantime, here are some suggestions:

* Use the search function for AK and troll the archives. There is a rich collection of articles and posts on all sorts of subjects in the areas of interest.

* In particular, see Echowars' “DC offset and You” thread in the vintage forum. Read the whole thing. It will take you into some interesting topics via the fundamental, variable measurements and settings that reveal the general health of an amplifier.

* The internet is well-populated with excellent primers on electronics. Many of these are adjusted to the 'electronically challenged' hobbyist like myself.
These sites may include general theory, Ohms law, identifying components, and interactive calculators. The more you search, the more endless seem the possibilities for learning and finding more interesting sites.

* Search for Elliot Sound Products. Rod Elliot in Australia has an archive of no-nonsense articles — mostly by his own hand.

* Also, there are some very interesting contributors in other online communities such as 'Audio Asylum', 'VinylEngine', 'tunerinfocenter', 'diyaudio', 'diytube' and others. The cumulative archive is very comprehensive.

* Searches will also turn up white papers that will answer specific questions for you about a wide range of topics. These are typically posted on-line by manufacturers

I hope that helps and is not so obvious as to be redundant. At least it may serve as a checklist. Of course the downside is that all this info comes piecemeal. A couple of readable books would be nice to have on the shelf. Cheers ... Lorne

Josh Carlson
09-07-2007, 11:24 AM
Hey guys, because these speakers are fairly popular, I was hoping that there was a lot of trial and error I could save myself from with cap replacement here, by way of meaning that some people here might have some fantastic recap recommendations on these speakers? My electronics knowledge is not that great, or else I would tear apart the schematic for these speakers and do more research, but I just don't have the time to learn about this the way I really want to right now.

Thanks for any input!

spkrdtr
09-23-2007, 07:51 PM
I am a new member here at AK. However, I have been a poster at Classic Speaker Pages for some time and am also a charter member there.

Seeing more than 14,000 views of this thread have been made - making it the 4th or 5th most viewed thread in the past year, I thought I'd add my 2 cents worth because it is a topic of such great interest.

With regard to recapping, some of the responses to this original post I have read refer to drifting and ESR but do not mention the problematic cap type in the text. It should not be assumed that drifting and leakage are associated with all cap types. Instead, those characteristics are most applicable to nonpolar electrolytics. If your speakers have NPE's, and are around 15 years old and up, you should seriously consider recapping. The reason: NPE's are made with a chemical called an electrolyte which is formed from a few different chemicals which degrade or can leak over time. That is the main reason for the limited life. You can consider it analogous to the typical life cycle of foam surrounds.

So, if you are ambitious and have 'elderly' speakers or, while you have that woofer removed for refoaming, you might as well check to see if your critical (series) caps are NPE's. Most speakers in the 10-30 yr old range do. If they are, then you'll be smart to replace them with film types. They are not susceptible to chemical degradation like NPE's and thus, will last MUCH longer without drifting in performance.

Two key questions arise:
1) What type of cap should I buy and what price should I pay?
2) Should they be broken in to accelerate optimum performance?

I have an 8 page study report, which, IMHO, answers those questions. I think you'll find some surprises in there. It goes well beyond anecdotal conclusions I've read time and time again in audio forums regarding what cap to buy and whether or not to break in. Instead, it takes a more scientific approach by visually and measurably characterizing the sonic signature of caps via waveform analysis using sine wave, pink noise and real music played thru a NPE, film/foil and botique film/foil cap.

Unfornately, the file size exceeds the AK limit for a .pdf file. Thus, anyone interested in a copy is welcome to contact me directly and I will gladly send a copy directly to you.

BrocLuno
09-23-2007, 09:42 PM
I agree that caps age, the time frame is similar to speaker foam for electrolytics from personal experience. We should probably consider re-capping whenever we refoam. Why not - it's not that much more work?

I do see many folks spec'ing 1% caps for replacements. All of the speakers I have opened to work on this last year (4 pairs from different MFGs) had 20% tolerance caps in there to start with. This tells me that the inductors and other components are likely 20% also?

Just going to 5% caps will be a big step in moving toward the engineers ideal values. I believe that almost all speaker electrical components have significant variance/tolerance. Does anyone have any data on overall tolerance from build to build?

It does not make sense to me to buy $10 caps for a $5 crossover (production cost)? Good poly/film caps can had for a few $$ each, or less.

EDIT - I did make an exception to my own rule - my EPI 100's. Since the entire crossover consists of exactly one cap (no component matching), I put 1% Daytons in there. If the speaker uses a multi-component crossover, I go one or two steps up from the factory spec's pieces with price in mind.

lorne
09-24-2007, 09:15 AM
Greetings spkrdtr: I am a rank and file member of AK, but I speak for all of us when I say welcome to AK! I hope that you will continue to share your knowlege and experience on our forums. Here are some comments on your first post:With regard to recapping, some of the responses to this original post I have read refer to drifting and ESR but do not mention the problematic cap type in the text. It should not be assumed that drifting and leakage are associated with all cap types. Instead, those characteristics are most applicable to non-polar electrolytics.This is truly a salient point. And, at least according to my feeble memory, I thought that we had covered that on this thread. Perhaps I should go back and read again. Still, you are very right to bring it up because it never hurts to reinforce the point.

Next ... I admit to being out my depth here, but I will dive in and 'take a bath' if indeed I am wrong:

I don't think that the NPE's are more susceptible to degradation than their polarised cousins. However, when ANY electrolytic capacitor is used in a circuit where little or no DC is present, they are compromised in terms of their optimum performance over the course of their operational lives. Again — as I understand it — DCV is commensurate with the ongoing reformation of the electrolytic paste. The electro-chemical reaction in the bipolar capacitor is the same as it is in the polarised version. By corollory, film capacitors are better in speaker networks in a number of ways because they are suited to an environment where only a very minute amount of DC is tolerated and riding on the essential AC signal. I failed chemistry, and was barred from physics, so if somebody burns me with some contradictory science here (perhaps you, spkrdtr), then no one will be more pleased than I!Two key questions arise:
1) What type of cap should I buy and what price should I pay?
2) Should they be broken in to accelerate optimum performance?...SNIP ...I have an 8 page study report, which, IMHO, answers those questions. Please see my PM; thanks for your invitation. I very much want to read your report. In regards to of #2: I have asked myself about what it is that electrons in copper, silicon, vacuums and other stuff could being doing so differently after X+n hours following their first power-up excitation than they were not doing before. As a failed science student (not for lack of trying), I have been attentive to more clever and scientifically inquisitive people such as yourself. But I have to admit that I have favored the reports that more closely matched my personal, subjective experiences — another reason why I would like to read your paper. I only hope that I am competent enough to read it with a fair and critical mind.

So far in this thread, it seems be agreed that replacing electrolytic capacitors is generally a very effective way to enrich the performance of speakers that were originally built using electrolytic types. A number of members have enthusiastically reported good results. And I would like to add this in anticipation of the post that follows yours: IMHO, the type of film cap is not as important as is the basic conversion from electrolytic to film capacitors. Here in Japan, large value polypropyline caps are generally expensive, and thus I have used Mylar or the generic polyester with excellent and dramatic results. At least one well-known investigator has claimed that many so-called poly caps are in fact polyester anyway. As for which film cap sounds good-better-best blah blah: enthusiasts may engage in experimentation, debates and in some cases considerable expense in the same was as tube rolling wire/cable stringing and all other sundry tweaks and mods. There may be a differences, but for the average enthusiast who is rebuilding some speakers, the essential payoff lies in the vast differences in the engineering of the two essential types — electrolytic and film.
Cheers — lorne

spkrdtr
09-24-2007, 10:37 AM
[QUOTE=lorne;1368482]

"...I don't think that the NPE's are more susceptible to degradation than their polarised cousins. However, when ANY electrolytic capacitor is used in a circuit where little or no DC is present, they are compromised in terms of their optimum performance over the course of their operational lives. Again — as I understand it — DCV is commensurate with the ongoing reformation of the electrolytic paste. The electro-chemical reaction in the bipolar capacitor is the same as it is in the polarised version. By corollory, film capacitors are better in speaker networks in a number of ways because they are suited to an environment where only a very minute amount of DC is tolerated and riding on the essential AC signal. I failed chemistry, and was barred from physics, so if somebody burns me with some contradictory science here (perhaps you, spkrdtr), then no one will be more pleased than I! Please see my PM; thanks for your invitation. I very much want to read your report. In regards to of #2: I have asked myself about what it is that electrons in copper, silicon, vacuums and other stuff could being doing so differently after X+n hours following their first power-up excitation than they were not doing before. As a failed science student (not for lack of trying), I have been attentive to more clever and scientifically inquisitive people such as yourself. But I have to admit that I have favored the reports that more closely matched my personal, subjective experiences — another reason why I would like to read your paper. I only hope that I am competent enough to read it with a fair and critical mind" ]

Sorry Lorne for the apparent confusion. Perhaps I should have not referred to the electrolytics as NON polar. I believe this led to your paragraph above regarding polar vs non polar. I just assumed NPE's were the standard for xovers and that was the ONLY electrolytic type being considered here.
Cheers!
p.s. my apologies here. This is my first post with a quote. It may be messed up.

Dragoon
09-24-2007, 07:13 PM
I've had a pair of KLH model 6s for a couple years now, and while they've had dead (seeming) tweeters, considering they're 45 years old and likely have all original crossover pieces internally... Yeah, this thread has told me that I need to somehow get in there and replace them... but how do i get into the cab without puncturing the woofer?

spkrdtr
09-24-2007, 10:08 PM
I've had a pair of KLH model 6s for a couple years now, and while they've had dead (seeming) tweeters, considering they're 45 years old and likely have all original crossover pieces internally... Yeah, this thread has told me that I need to somehow get in there and replace them... but how do i get into the cab without puncturing the woofer?

Looks like you have an earlier pair with epoxied in woofers. Yucch!
Suggest you visit the classic speaker pages discussion area re. Advent and search Model 6's. There are many posts there regarding folk's experiences breaking into those beasts to do a recap job.
99% of the time a bad tweeter cap is the culprit.

Dragoon
09-27-2007, 03:13 PM
I had a look, and it's apparent that i'll need professional help (for getting in), and a day that needs killing... ah well, at least they function beautifully as they are, and go well with the advent 1s I recently snagged for free.

joe@magi.net
09-29-2007, 07:57 AM
Hi you guys, really interesting thread, I am new to AK, old to pro-audio. Retired pro audio designer, a lot of experience with caps, golden ear listening tests, and years of feedback to my designs in the field. I don’t usually express my opions in forums, a lot of bad experiences in the antique radio forums from a lot of lurkers just wanting to trash people trying to help, but this forum seems a lot better, I’ll give it a try. If any of you guys are from the recording industry, you would know my most successful design, the MCI JH-600 console. Or if you are into antique radios, I am sure you know me from Epay as radiosphonos. Anyways, I am old, and senile from 40 years of low level lead poisoning from solder, sinkers, and bullets, I’ll ramble, and forget in the middle what at the beginning I was decided to say in the end, and typing with two fingers is no help, this kinda talk is so much easier in person and with a white board. In no particular order, I believe I can give some of you guys a little more information to think about. Ok, electrolytics and several issues about them raised in this thread: if they are old they are not what they used to be, and by a lot. And for several reasons, this is a can of worms, yikes. Ok to understand this you need to consider the basics of capacitors in general and lytics in particular. A capacitor is simply conductors near each other, usually considered “plates” (planes) and for practical construction, parallel to each other (this is to make wanted capacitors, there are unwanted capacitors everywhere in our circuits like wires near each other, or lands on a circuit board, elements in a tube and on and on), but let’s discuss manufactured practical capacitors first. 2 Parallel plates or planes of conductors separated by an insulator. Farad(or somebody) discover way back when that when electricity was applied current flowed. This current would start high and quickly drop off and then stop .The capacitor to store energy is determined by the area of these plates, and the distance between them. Move em closer, capacity increases, double the area, double the capacity, Already with just this much info in a basic capacitor we are at the root of where a lot of the things this thread discusses originate. Without a white board, I’ll try to explain in writing. Ok, BUT, moving them closer to increase capacity (to make the capacitor smaller, DECREASES what voltage we can use this cap at. At some point they get close enough for voltage to jump (arc) the gap! This is the ‘breakdown voltage”. Different insulators have different properties and allow us to make our caps bigger or smaller depending on their breakdown voltages. The insulators can have another property, they can conduct small currents when their breakdown voltage isn’t exceeded, like say we used cardboard. Perfectly dry is has no leakage, but if it absorbs humidty from the air, water conducts electricity and it can become leaky, allowing a small current to flow, so our capacitor could have a leakage that varies from day to day dependent on humidity. Another important design issue here is what insulators do when they break down. Air insulator, after it broke down (arced) if the voltage is lowered, becomes an insulator again. Paper might have burned, and left carbon ash that conducts, and thus be leaky, more or less depending on how long the breakdown sustained. Tantakum capacitors, as great as they seem to be with their small size, low DCR and even lower Inductive reactance have the sad disadvantage that if their voltage rating is exceeded EVER, even for a pico-second, they blow shorted and never recover. That’s why you’ll never see em used for filter in good designs, they are relegated by knowing engineers (read that as ‘people who have burned down buildings with their designs”) to timing circuits and running Chinese made toy cars and helicopters. The first caps were air insulated, then glass, which was way better than air. Then cardboard, then oil immersed cardboard (or paper), because the oil didn’t conduct and didn’t allow humidity to enter our insulator. Electrolytics are planer conductors (two pieces of aluminum foil) wound into a cylinder, so our part is small instead of like a yardstick. separated by an electrolyte, which is a chemical paste that has the advantage of being a very good insulator with a very high breakdown voltage for the distance between the plates, allowing us to make very small parts with a very large capacitance Sideways now, we also can consider another factor, the ESR. For discussion’s sake lets make up a capacitor: suppose two pieces of one square foot area separated by an insulator yield a capacity of 12 microfarad. Great, it could be 12’ by 12”, but could also be 1 inch wide and 144 inches long (and could be rolled into a cylinder so it doesn’t stick twelve feet out of our product, more on this engineer’s nightmare later!). so lets leave it unrolled for now, and use 1 inch wide and 12 feet long. Lets connect to it at one end. Ok, assume that our aluminum foil has a dc resistance at 1’ wide of .1 ohms per foot. The capacity is 12 microfarad, BUT some of the capacity is in series with a dc resistance. Consider this as 12 1 foot long 1 mfd capacitors in parallel. The first one nearest our connection is 1mFd with no series resistance in parallel with another mFd in series with .2ohms, and the next is a mFd in series with .4 ohms, and on to the twelfth capacitor in series with 2.4 ohms! I ain’t into thinking too hard yet this morning and doing the math, but you are going to have a 10 mFd cap with an esr (equivalent series resistance). Now, suppose we hooked up our wires in the middle. Then thinking about this as twelve capacitors paralled, the ends are only 6 feet away with a DCR of 1.2 ohms, giving us a lower esr than if they are on one end. Now it gets worse, let’s roll it up. Great, it is small enough now to be practical but what have we done. We made a coil, coils exhibit a property known as inductance, got to do with current in a conductor creates a magnetic field, take away the current and the magnetic field remains for a bit, decays slowly compared to the disappearance of the current, and then a conductor in a magnetic field generates a current, so this back EMF creates a magnetic field, what it amounts to is unlike a capacitor which conducts better and better (theoretically) at higher and higher frequencies, inductors oppose current flow at high and high frequencies. We calculate or measure this flow in ohms, which is confusing, but it is called inductive reactance and is frequency dependant. Considering our model capacitor again with the wires on the ends again, we have 12 1 mFd capacitors in parallel but each further on has a DCR of 2 times .1ohm, and an XsubL (inductive reactance) in series, reactance being related to the number of turns and the frequency of operation. Now if you sketch this and crank the numbers you will find that if we hooked our connections at opposite ends, we would have the smallest inductive reactance and that is how electrolytics are made. Smallest DCR too. It is still big at high frequencies, originally we realized this back when and on decoupling electrolytcs, especially on integrated circuits that like to oscillate, we have been paralleling them with a small value mica or ceramic, to bypass the very high frequencies. On paralleling lytics with small value caps, I would have to see the circuit, it depends on the lytic ESR at the frequencies of operation, and the goal. I can say it doesn’t hurt anything, not ever, and if you aren’t an engineer, go ahead, it makes a big difference in some places, sonically and in active circuits, stability. Ok, long long ago, someone discovered while experimenting with insulators and capacitors, in the search for high breakdown voltage insulators in smaller thicknesses, with the goal of reducing cap size and more important reducing capacitor cost of manufacture, that if they saturated paper with an electrolyte paste (a chemical that conducts electricity) and then applied a slowly increasing voltage, the electrolyte would electrochemically change into an extremely efficient insulator (now, an electrolyte conducts electricity, but the electrolyte in electrolytic capacitor is electrochemically changed to an insulator, and applied voltages maintain this insulating condition, so I belive “electrolytic capacitor” is a wrong description, although it is used to make them, they should be called ‘insulatic capacitors” or something, as long as an elecrolytic is working, it has no electrolyte in it, it has an efficient insulator). Until the last 20 years or so no other capacitor type exhibited the amount of capacity per size, and they are cheap to make, no exotic materials, just aluminum foil, paper, and goo, so also capacity per dollar, always a big factor in manufacturing, often the biggest. (don’t get me started).
Lytics bluntly suck, but they do do filtering and sometimes decoupling well, in fact for the dollar, better than anything else. Small size per capacitance, low cost per capacitance, excellent self healing/recover after an overvoltage, years ago, only practical process to get high value capacitors, their was no other. This has lead not only to their almost exclusive use in power supply filtering and decoupling, which is a good engineering choice with the exception of their lifetime, but also to their use where they really suck, like in crossovers (suck for MANY reasons). Never in a blind AB golden ears listing test have they ever been chosen as the best choice for audio flowing through them, unless there was something else they were doing like leaking helping. If you can replace a crossover lytic with some other type of capacitor, you will always be better off. On the other hand, if no practical substitute is available because of size or cost, well, lytics have worked all this time and will keep working. BUT, lytics age, and more than one way. Older ones especially get dry, capacitance changes, breakdown voltage lowers, ESR increases, all bad things. Ideal maintenace of a lytic is in circuit, voltage applied and the voltage should be near it max operating voltage. Everyone knew that when you replace a lytic, to use the same voltage or higher. BAD. If you use say a 100 volt lytic in a 100 volt application, geat, the factory formed dielectric is maintained, the more it is used the longer it will live. If you replace it with a 450 volt part, yes, it works, today, the dielectric will reform at the new voltage, and it wasn’t designed for that, there is too much x or Y, and although what reformed to the new voltage is happily working, the extra X or Y has become electrolyte again (read that as “conductor”), leakage, changed capacity, etc. Not just well meaning techs, I have seen many engineers design a higher voltage part in because of availability, not understanding all the ramifications. Even a new lytic is a potential problem, look at the daycode, if it is never used but is more than 2 years old, throw it away. I was a great one for walking in the stockroom and announcing trueisms like that and being responsible for junking millions of parts, (like the time I announced that all audio ic’s should have tinned brass or copper legs, and if a magnet sticks to the legs, throw em away! But that is another story, although I will say, even in crossovers, all parts should be non-ferrous leads, terminal strips should be plated or tinned non-ferrous metal, same with binding post screws, etc.). Electrolytics (insulytics) maintain their insulating dielectric when voltage is applied to them. When they ain’t they slowly decay. It depends on the manufacturer, storage conditions, (temp) etc etc, but typical lytic infant mortality rises quickly with age. Say a particular group of caps are all good the day the were made, at 2 years storage and then use, 5% failure would be typical and at 5 years maybe 20 percent. Yes, reforming would greatly lower them numbers, but they would never meet new specs, lytics are cheap, why screw around. Ok, back to the thinking about this thread, lytics in crossovers, non-polar. We original used polarized lytics in non-polar applications by putting in series back to back. the capacity is half the value of on. The breakdown voltage is the same as either one. The diode trick sounds good in theory, but sounds terrible, especially as an audio waveform crosses the diode “knee” at .6 volts. The original non polar capacitors were two lytics, squished together round and put in the same can. Then someone got the bright idea of three pieces of aluminum foil wound together, connections to the outside pieces, cost of manufacturing goes down, size went down, great. BUT they are still lytics with lytic bad properties which in this case is relatively short lifetime, and often the inductive reactance (which can be negated by paralleling a small value mica or film.)
Ok, where was I? Caps in parallel are fine, never determined a difference from one cap, except it might be ugly (10 film .1’s in parallel, back before they made a 1 mFd film). Wiewound resistors – get em out of the signal path, they are fine in power supplies. Well, I am sure I had more I wanted to comment on, but as I predicted I forgot, I ain’t gonna read the whole thread again, wife took the twins to waterpark for their birthday, I have a very rare day off, and I am going fishing, flats or offshore?, always decisions. I hope I have given some of you experienced people a little more stuff to understand as you are working your hobby. Thanks for reading this far if you did, now I gotta see if this forum can take a message this big or if I gotta put on one of my servers and link – joe
Shoot! I just remember I came to this forum seeking advice on a subwoofer for my stereo. sorry if i bored you, one of my pet subjects, you know.

lorne
09-29-2007, 10:15 AM
Bored? NO WAY! Thanks Joe. I read every word. A good primer — and blast if it confirmed some of my worst fears. For example, What about my headphone amp that I started building about 5 years ago and never completed? It's 90% finished, but those banked up Nichicon filter caps are five years old as soldered on the board, and maybe a year in the kit waiting to be sold to me. And then there is a drawer full of various electrolytics — all just getting older and more senile. Sigh ....

Can you comment on something we don't hear about very often. What issues surround NON-electrolytics — film capacitors and so on. They can become 'resistive' with age, can they not? I am not familiar with catastrophic failure as in the case of leaking, shorting or opening electrolytic capacitors, but do they too have optimum life spans?

Welcome to AK. I for one will be looking for your posts.

Cheers — Lorne

spkrdtr
09-29-2007, 11:28 AM
Bored? NO WAY! Thanks Joe. I read every word. A good primer — and blast if it confirmed some of my worst fears. For example, What about my headphone amp that I started building about 5 years ago and never completed? It's 90% finished, but those banked up Nichicon filter caps are five years old as soldered on the board, and maybe a year in the kit waiting to be sold to me. And then there is a drawer full of various electrolytics — all just getting older and more senile. Sigh ....

Can you comment on something we don't hear about very often. What issues surround NON-electrolytics — film capacitors and so on. They can become 'resistive' with age, can they not? I am not familiar with catastrophic failure as in the case of leaking, shorting or opening electrolytic capacitors, but do they too have optimum life spans?

Welcome to AK. I for one will be looking for your posts.

Cheers — Lorne

Lorn, here's my 2 cents worth:
Nichicon may not be a good choice based on my recent capacitor study referenced in an earlier post within this same thread. I purchased 2 from RS and both had horrible ESR's and they were brand new!
Replacing NPE's with film types usually results in a 'brighter' sound because the old NPE's ESR has drifted upward resulting in added resistance seen by the tweeter. The immediate drop in ESR that results from replacing that old or poor quality NPE is heard as higher volume that folks mis-construe as brighter sound. This is shown clearly in my report comparing NICHICON with Solen and Hovland 4.7 uF MPP film caps. I replaced Nichicon with a Parts Express NPE and found it's ESR was much lower - almost as good as the MPP caps.

I have not heard of or, read about aging issues with MPP or film/foil caps.

In summary, that brighter, more open sound re-cappers rave about may indeed be simply the tweeter playing like it did when the speaker was brand new.

BrocLuno
09-29-2007, 04:54 PM
Phew !!!! That's a lot, but well worth it. Now I get the bit about caps "muddying" the sound (internal inductance and leakage?).

Still thinking the 5% or 10% poly caps are the most reasonable way to go if the MFG spec'd 20% parts to start with?

fiddlefye
09-29-2007, 08:47 PM
That explained everything I "wanted to know but was afraid to ask" about caps. I hope you don't mind, but I saved all that in my files for future cogitation (Saturday night ain't ideal....). Pesky and problematical critters, those capacitors, aren't they?

lorne
09-29-2007, 10:07 PM
Thanks Carl ... some interesting points.

justrideit
10-01-2007, 04:09 PM
As an example, I have 3uF 50V caps to replace. I called parts express and they give me part#'s that coincide to a cap rated 3uF 250V.

So do I need to match the caps exactly (uF and V) or is this cap rated at a higher voltage OK to use?

I have 50V, 75V and 100V caps to replace. All the caps they recommended were 250V, 1% Daytons.

Urizen
10-01-2007, 04:12 PM
So do I need to match the caps exactly (uF and V) or is this cap rated at a higher voltage OK to use?

I have 50V, 75V and 100V caps to replace. All the caps they recommended were 250V, 1% Daytons.

Good caps. You're fine using a higher voltage.:thmbsp:

joe@magi.net
10-06-2007, 07:30 AM
Paper foil capacitor deterioration with age (or “why all paper foil capacitors should be replaced”) yea, yea, yea, I know, those old original capacitors sound best, etc etc etc. Well, , sorry, being an engineer, I have to face facts, and the facts are, although they may sound good to you, they do not sound as they did when new, and replacing them with high quality parts can guarantee they sound closer to what they did originally. Facts are facts, these old parts ARE deteriorated; paper was a good choice of an insulator back then, these parts have lasted decades after all. BUT, not for indefinitely. There are several major and minor deterioration with age problems. Paper ages, look at any old piece of paper and you can see that. Yellowed, hardened, brittle. Heat ages paper faster – we restore old electronics and reproduce paper tags and labels as needed, and we often age by baking at 300 degrees for just a couple minutes. Minutes! What has decades of hot enclosed chassis done to the insides of these caps? But the most important is that paper, while a very good insulator, contains moisture. Also, from the paper manufacturing process, paper is slightly acidic. And, even if in manufacturing, all the acid was properly neutralized, the residual moisture in the paper, cellulose, slowly forms acid. In circuit, with an applied voltage, these capacitors, two electrodes of aluminum foil with a paper insulator, have a tiny leakage current that mostly flows through the tiny moisture amount in the paper. Now, this is a cell, no different that how we plate metal, in other words, aluminum from the more positive electrode, the anode, with plate through the insulator and onto the more negative electrode, the cathode. Besides eating away at the anode, and thickening the cathode, a trail of metal or metal salts is deposited along the path through the paper. It takes a long time, decades, but what happened is that the capacity changes and more important leakage increases. Unlike electrolytics, these can’t be re-formed by voltage. Also unlike lytics, that lasted best with more usage, these deteriorated faster with more usage, a reason why NOS old caps are generally better than used. There are many bad complications going on at the same time. Leakage current times the applied voltage equals power being dissipated in the part. What that means is that it is self-heating. As leakage gets worse, the heat can become appreciable. Sideways for a moment, plastic encapsulated capacitors like bumblebees and black beauties seem pretty sealed, BUT . . Plastic expands and contracts with heat and looking at the cases you can imagine that circumference expansion is going to be greater than the expansion on the round end caps, so microscopic cracks with form, allowing more moisture to enter, further accelerating deterioration. Add in that with leakage there is self heating with use, cooling between times, the problem is only getting worse, and will never get better. Leakage. Well, today, slightly leaky caps affect the sound, and if you AB a leaky cap amp and then change them, you may even think it used to sound better! Yup. Going sideways from my points even further, our ears have millions of years of evolution in a natural environment, you know, jungles, forests, etc. well, in nature sounds that have traveled a distance by trees have even harmonic distortion, and it sounds entirely natural to us. There is almost no way in nature to color sounds with odd harmonic distortion. And in blind AB tests with controlled amounts of distortions, people always pick small amounts of even as better sounding than none, even larger amounts of even often preferred to amounts approaching several whole percent! And ALWAYS, people dislike any amount of odd vs none, even to hundredths of a percent, and for some golden ears, thousandths of a percent! Unfortunately transistors with a few exceptions are rich in odd harmonic distortion, and so is sound traveling by metal and plastic. Tubes have even harmonic distortion, so does wood of course, and so do transformers. Just by evolution of radio we accidentally did the right things first, and then as we did wrong things (transistors, plastic, metal, it is unfortunate that the Japanese were taking over our radio, television, and home entertainment and learned that by mass marketing and lower prices techniques they could sell Americans anything, better or more often, worse. Ok, going back a bit. Leakage currents through these old capacitors in the coupling between tube stages, affect grid bias and position the tubes operating parameters off the linear part of their curves and still working, they generate more and more even harmonic distortion. Yup, the old caps DID sound warmer! So what? They no longer sounded as they did when new, no longer sounded as it did when this or that old audio genius designed them. Replacing the caps puts you back there. If you like warm even harmonic distortion get it somewhere else. Try different phono pickups, change tube types all through the signal chain, especially experiment with different speakers and cabinets. The warm sound from old caps is bad. It is in the long run temporary and, more important, it is wearing your tubes quicker shortening their useful life, as they go bad completely, they will take out tubes, permanently ruin transformers and MOST important, potentially cause a fire, either themselves, or at the tube and especially the transformer they are cooking. You know, when you recap and try to AB the recapped sound, measure tube and transformer temperatures before and after – you will be surprised. Back to an interstage coupling capacitor. Connected to the plate of the first tube with a high positive voltage and on the other side to a grid with a negative voltage with respect to that tubes cathode, a small negative to small positive voltage with respect to ground, depending on individual circuit. The leakage current is raising the grid voltage more positive. This is increasing the idle current, and many tubes with increased idle current, is much hotter tubes, certainly affecting tube life, and all the se idle currents are increasing the power supply’s power dissipation, read that as hotter transformer, hotter chokes, hotter dropping resistors, hotter chassis. Heat is the enemy of electronic components, and I dunno about you, I really don’t want to be buying any more expensive matched output tubes than I have to, and certainly not trying to find power and output transformers than I have to. As these time bomb capacitors self-destruct, they will take out all these various parts. I know from experience that many techie people working on this old stuff, having documentation with tube element voltages right there in front of them, think those are “ballpark” voltages. yeah right. Electronics and electricity are sciences, there are tolerances of voltage determining parts, but wake up – they are NOT that loose! Those voltages are near what they should be. When you see higher grid voltages it means coupling caps are leaking. When you see lower supply voltages, it means filter capacitors and de-coupling caps are leaking. The fact is all those paper and foil caps, no matter how nice and shiny new they look, are really no good anymore; they WILL fail catastrophically sooner or later, will destroy tubes, transformers, and could burn a house down. You only have to needlessly burn one house down to give you a whole new outlook on old capacitors. Modern capacitors, especially audio specialty parts, ARE great replacements, and from years of experience with golden ear blind AB tests, and engineering analysis of circuits and circumstances, and, most importantly, using engineering knowledge of the facts, and common sense, I am saying all the above with a high degree of confidence, replace old lytics and paper foil caps, in crossovers from common sense, in amps and receivers for safety. Safety for the hard and expensive to replace tubes and parts, safety for someone’s life and property. Hope all this helps in your thinking about our hobby!

ka7niq
10-06-2007, 05:27 PM
Probably built with electrolytics -- undoubtably past the end of their life cycle. Get into them, the values are probably stamped on the caps. You can find nice electrolytics here:

http://www.partsexpress.com/webpage.cfm?&DID=7&WebPage_ID=72

You can try some nice polypropylenes to see what you think -- I tried it with some Old Advents and the top sounded too hot.
This is an interesting thread.
My experience has been that changing all the caps with different types of caps changes the speaker.
And, not always for the better either, unless the caps were just horrible to begin with.
I had Celestion SL 600's, and so did a friend.
He spent megabucks on all new snake oil caps, installed them, ruined the speaker.
He is STILL waiting for the speaker to 'break in". :tears:

I have done several cap experiments comparing electrolytics, metallized Poly, and Polystyrene/Teflon etc in tweeter circuits of various speakers I own, or have owned.
Want to know what the "best sounding cap" is ?
It all depends on the circuit/speaker it is in, IME.

In one pair of speakers, I was unable to beat a replacement Electrolytic with any capacitor I tried.
Now, THAT electrolytic was a Panasonic Electrolytic, reputed to be a good capacitor.
It "liked" that ciruit/driver combo I guess ?

signal-dude
10-15-2007, 10:14 PM
You can try some nice polypropylenes to see what you think -- I tried it with some Old Advents and the top sounded too hot.[/QUOTE]

Greetings All, I just finished a recap and recoil? of a pair of 1975 Large Advent Utility's. For some background they sounded OK at low watt levels, 1/2 watt or so but crank them up higher and the music blended into into a mush is my best description.Also what I would agree with as a too hot mid range.

So after researching all about cap soakage,leakage, DF,DA,ESR, ESL, Polar, Non Polar, Mylar,Electrolytic,Polypropylene,
Teflon,Metal Polyprop,PIO, Film and foil, Solens, Mundorfs, Sonicraft, Auricaps, house brands, Jantzens, Kimbers, and all that I decided on using Solen MPP's from PE.

And also changing out the ferrite core inductor in series with the woofer with an air coil of the same value and DCR as the original. Also from PE. And what I also did to cool off the hot mids was to change the 3 ohm sand resistor in series with the tweeter with a 5 ohm Mills resistor that according to my calculations should lower the voltage to the tweeter by 2 db or so.

Well, after the parts swap to say the change was startling would be an understatement. No more mush at higher levels and the mids were much more balanced to the low end. I heard instruments that I had no idea were there.

You won't hear any Audiophool drivel from me about lifting veils and such but I just heard good clear music coming out of my vintage Advent's. My guess is that the old Electrolytics had some awful DA in the 10 percent range or more. Probably what I described as mushy sound as the cause. They checked out at the labeled capacitance but thats as good as I can test them.

So the combo of better caps, reduced drive to the tweets and an air core woof inductor made a substantial increase in my enjoyment of these old gals. As many wiser heads have said here and elsewhere, get rid of them Electros and slap in some good caps of your favorite flavor. My choice may not be your choice so YMMV.

And as a final comment I would have to say the different parts did not change the voicing of the Advents just cleared it throat, sorry....

Marcus

OvenMaster
10-15-2007, 10:24 PM
Reading all this tells me that when I need to recap my KEFs I'll be sticking with OEM types: a 10μF 100wvdc polarized electrolytic and a 4.7μF 100wvdc non-polarized electrolytic. I don't need the "brighter" treble that comes with polys or film types.
Tom

spkrdtr
10-16-2007, 06:34 AM
Reading all this tells me that when I need to recap my KEFs I'll be sticking with OEM types: a 10μF 100wvdc polarized electrolytic and a 4.7μF 100wvdc non-polarized electrolytic. I don't need the "brighter" treble that comes with polys or film types.
Tom

Your choice of new NPE's may also yield a brighter treble. It all depends on how much the old one's ESR drifted upward. If the old cap's ESR rose well above 1/2 ohm, good quality new NPE's will most likely be significantly lower and thus allow more voltage to the tweeter.
The important thing to remember here is restoring the original ESR will result in restoring the original SPL output of the tweeter. That can happen with most any type of cap. Additionally, the choice of NPE types will inevetably lead to the same inherent deterioration in future years as occured with your current ones. Thus, I tend to favor film types for there inherent long term stability when recapping xovers for my customers.
I think Signal-Dude did a good job with his careful selection of cost-effective, components.

lorne
10-16-2007, 11:05 AM
Thanks signal-dude for some interesting comments that I will remember when I finally get around to the second phase of altering my old Tannoys. Old guys my age here in Japan are of the opinion that you should build a shrine for these things, then venerate and leave them untouched forever. If that had become my religion, I'd have abandoned or sold them off years ago.

davesnewTT
10-24-2007, 08:20 AM
hello,

i've recently acquired some 25-30 year old homebrew speakers. they've got good bass, decent mids as well, but not enough highs. after reading this thread i figured they needed a recap, so i recapped one of them but to be honest i don't hear any difference. i was hoping someone here could tell me if there's something else that might be causing this.
now these aren't exactly sophisticated homebrews, so i guess tweaking won't turn them into anything spectacular, but since they were free i figured i'd be a good learning oppurtunity. so that when i run into something good that needs repairing i'll know (a bit) what i'm doing.
right. so only one of the drivers is labeled properly:
woofer: wharfedale 3010, 6 ohm DC, 25 cm/9"
mid: only says 3/ 13 or possibly 73 / 5 , 12.5 cm/5"
tweeter: only says "made in england", it has a clear purple plastic dome, one inch across.
i've also attached the crossover:
R1= 3.3 ohms
C1= was 6 uF 50 V, replaced with 6.8 uF 100V
C2= was 25 uF 50 V, replaced with 22 uF 100V
I1= 0.5 mH
I2= 4.0 mH
I3= 0.3 mH

i'm not exactly an electronics expert, but does the crossover wiring mean that that resistor (R1) is the thing limiting output to the tweeter? is it safe to replace it with a lower rated one and thus give the tweeter more power?
thanks in advance, hope the AK experts can help me out

lorne
10-24-2007, 08:45 AM
This might be the subject of a new thread, and I recommend that you start one for the most effective response. There are some really knowlegable people in AK who may help you with this as a learning project, and in the process help others like myself.

I cannot help you much if at all here. But here are a few things to think about as you prepare to start your new thread: Try to identify as best you can the three drivers used. Then try to get as much if any detail in the way of specifications — even if you don't understand them. Hopefully, these speakers were assembled with some rational consideration as to the engineering and compatability of the drivers, cabinet and Xover circuit. There is a LOT of stuff to engineer in a 3-way speaker, and something really satisfactory is very rarely the product of good luck. Just speaking for myself: if I were thinking of a ground up homebrew, I think that I would be sticking to a single driver design — something that has attracted some intense interest and devoted fans.

Good luck, and I'll be waiting to see what replies you get ... here or ... there.

davesnewTT
10-24-2007, 09:36 AM
thanks for the response lorne. so can i just move this message or do i need to repost it? guess i'll just repost it anyway...
as for the engineering design, i don't have a clue where to start myself but i've the feeling these speakers aren't terribly advanced. they're mounted in a simple rectangle box, vibration damping inside consists of egg carton and glasswool (that's what we call in holland, not sure about the translation; the stuff looks like what's used in sleeping bags) and the mid's isolated from the rest by fitting it in a cardboard tube stuffed with dark cloth/fibrelike subsance

lorne
10-24-2007, 04:28 PM
Hi: I'd just repost with a subject line like "HELP with strange speakers please." Try to take some photos. Someone will probably recognise the drivers if you can't lift any description from the units. If there are any ports, you note where they are or put them up as pics. If you need any help putting up attachments (pics), write me a private message and I'll help you. BTW, I think that Americans know 'glasswool' as fiberglass, and perhaps the British have come to use that term as well. In Canada during the 1950's, we used both the word glasswool and fibreglass.

onepixel
10-24-2007, 05:40 PM
wow... very informative thread. I look forward to recapping some old speakers now!

Thanks,
Carl

salb203
11-19-2007, 07:02 AM
I have an 8 page study report, which, IMHO, answers those questions.
****snip****
Unfornately, the file size exceeds the AK limit for a .pdf file. Thus, anyone interested in a copy is welcome to contact me directly and I will gladly send a copy directly to you.

I would me interested in the PDF file. I can also host it on my server if others want to download it. My email address is salb203 at optonline dot net.

Thanks,
Sal

gkimeng
11-19-2007, 02:45 PM
My question however isn't answered in any of the posts. At what point does a speaker need to be re-capped? How many years after original purchase? How long in storage without any use before it's time to re-cap? Do the caps last longer if the speaker hasn't been played, or if it's been in constant use?

Thanks for the help!

In an ideal world, the answer would be, "when testing in an anechoic chamber shows that the frequency response has significantly changed from the original specs." If you don't have access to an anechoic chamber (and how many of us do?), there are some times when the need is fairly obvious, such as there's no sound coming from the mid or high drivers even though the drivers test ok, or even though there is sound, your speakers sound "muddy" and nobody else who has them say they sound that way. If that happens, I'd open up one of the cabinets and start testing caps, and if they test bad install replacements that are as close to the originals as I can get. I'm not inclined to try to out-think the original designers, and if replacing caps that went bad after 20 years with ones that aren't "better" means I might be back in there in another 20 years, I can live with that.

lorne
11-20-2007, 07:55 AM
I'm not inclined to try to out-think the original designers, and if replacing caps that went bad after 20 years with ones that aren't "better" means I might be back in there in another 20 years, I can live with that. As limited as I am, I'm inclined to 'out-think' the original designers. You might think of it as the DUH! factor. Why would I want to assume that an electrolytic capacitor, which certainly must have been deteriorating even after a mere seven years stint of duty, is a more enviable device than a film capacitor, which is naturally more suited to the environment of a crossover network in every way? And why would I want to retain the same electrolytic caps in place for another thirteen years, simply because some committee of engineers signed off on a project after the bean counters had finished with the per/unit costs. DUH! Electrolytic caps are just NOT the correct part for the application! And don’t you think that the engineers knew that when they designed the speaker?

And OK, so what if the voicing changes? Well, in some cases it will be an improvement. In some cases a film cap may not be an improvement over a fresh electrolytic type. In other cases, there may even be a substantial and distasteful change. Should the latter be the case, the enthusiast faces the choice of either tuning the balance of his/her system to suit the newly voiced speaker, or reverting to the electrolytic capacitor complement and replacing them MUCH more frequently than every twenty years.

Electrolytic caps deteriorate on the shelf! And they do not get any fresher in a network that dishes out VAC all day either! Barring cost, the engineering limitations of the electrolytic capacitor make them second choice for speaker networks. And waiting for them to fail is akin to a death watch. For some period of time, a function of life is noticeable but diminishing and fading into oblivion. If capacitors were worth the price of a Formula One racing engine, there may be a point to holding on. But they aren't — and there isn't!

I have done enough of these change-outs to satisfy myself in these matters. Some change-outs provide more or less ... this and that. But in the end, they were all worth while. In some cases the results were transformational in terms of sound. Virtually all were provident of some increased emotional involvement with the music.

Each to his/her own. If it makes no difference to your ears ... well then forget it. I have 60 year old hearing (tested to be average for my age), and these differences still seem obvious to me.

My interest in responding to the post above rests on this: older speakers may be a resource for retaining an experience ... a sensibility that belongs to an alternate experience of sound reproduction that is passing into history along with two channel analog recording. If these units are just allowed to decay, their essential worth my be under appreciated. They may become increasingly discarded as featureless lumps of particle board and iron.

I believe that there are millions of nice speakers out there ready for those of us who have tight budgets. These old speakers can provide us with great performances that can enhance our lives. Far too many of us cannot afford $1,000, $1,500, $2,000 for a pair of new speakers — many of which cannot be said to hold there own in terms of materials and build with SOME of the older products. I own three sets of speakers that years ago cost a significant amount of money. I bought all three for a small fraction of their original cost. Just one example is a pair of Sansui speakers I have recapped with film caps — SP-G88's — a purely Japanese domestic, 3-way, transmission line speaker with double layer carbon fibre woofer and mid, and titanium tweeter. These are not ancient speakers, but new film caps transformed them into something special from something just acceptable and interesting. I have to admit that the addition of some NOS Richard Allen tweeters boosted them into being distinguished performers — for a fraction of what it would cost to get something of equal performance today. But I dare say that all would have not been discovered had I retained the big film-cap bypassed electrolytic caps that were the original parts. These speakers are big, ugly, and heavy — real WAF negatives. But, besides a set of Magnaplanars that I lived with for three years, they are the best I’ve ever had — after new film caps.

My question however isn't answered in any of the posts. [1] At what point does a speaker need to be re-capped? [2] How many years after original purchase? [3] How long in storage without any use before it's time to re-cap? [4] Do the caps last longer if the speaker hasn't been played, or if it's been in constant use?
(1)
If you have electrolytic caps installed in your network, I'd replace them within seven years. Many audio people will not use an electrolytic cap that has been sitting on the shelf unused for seven years. (But, see #4) Yes, they will work, but possibly not at their optimum design value. An electrolytic capacitor in a crossover network may be considered to be even at greater hazard than a shelf item as it has not been blessed with the VDC that this design enjoys, but may have exerienced more stress from heat. (See a post by a previous contributor.)

(2)
I'd look to seven years as in #1.

(3)
I'd look to seven years as in #1

(4)
Unless I have a gross misunderstanding, I'd say that it does not make much difference. But because crossover electrolytics are often larger and very robust specimens, they may resist idleness and use in a VAC environment longer than their minature polarized and non-polarized cousins. But, if we take a sloping away from optimal performance as a determinative, changing out electrolytic caps within a seven year period is a safe bet.

Newcomers are free to chose from these varying points of view. I have arrived at the last 4 points in my reply to Scorpion by way of a collation of many, many readings and opinions offered by more astute enthisiasts and professionals. It is up to readers to decide if I have done my work properly. And that is what we are about here at AK. I think this ... some one else thinks that. And science intervenes and has a firm guiding hand on the impartial, cogent observer. You readers be yer own judge — of course!

gkimeng
11-20-2007, 10:03 AM
As limited as I am, I'm inclined to 'out-think' the original designers. You might think of it as the DUH! factor. Why would I want to assume that an electrolytic capacitor, which certainly must have been deteriorating even after a mere seven years stint of duty, is a more enviable device than a film capacitor, which is naturally more suited to the environment of a crossover network in every way?

I was referring to speakers that did not suffer measurable cap failure until well into their 20's or older. And I have tested caps of various types in 50-year old speakers that still met original specs. Some vintage gear was just better designed and built than others.

I am not saying I would leave caps that test as failed in place because they are "original," merely that I would not change out original caps in a high-value classic speaker on a knee-jerk basis merely because they are old without testing them first. Age is certainly a reasonable basis on which to presume that all the caps should be tested.

I agree with you that it would probably be worthwhile to try to out-think the designers of a speaker that showed signs of failure after only seven years. The possibility that a speaker may re-voice due to component changes is certainly less undesirable than a speaker that doesn't work at all, and if the speakers were of questionable worth to begin with and were obtained cheaply, there is probably nothing to lose by experimenting. But I would be more likely to just assume that the rest of the unit was designed and built with similar poor quality and replace the entire POS ASAP after that before something else blows. YMMV.

lorne
11-20-2007, 07:06 PM
And I have tested caps of various types in 50-year old speakers that still met original specs. Some vintage gear was just better designed and built than others. Very interesting, and I for one am taking note. If you have any good pics of such an old network with the caps showing up nicely, I'd like to see them. Also, would you please post details of how you tested the caps, and what instrument you used. I'm also interested if there were any tests involving actual signals, or were the tests for measured capacitance only? Best ... LORNE

BECtoo
11-20-2007, 09:10 PM
I was referring to speakers that did not suffer measurable cap failure until well into their 20's or older. And I have tested caps of various types in 50-year old speakers that still met original specs. Some vintage gear was just better designed and built than others.

I am not saying I would leave caps that test as failed in place because they are "original," merely that I would not change out original caps in a high-value classic speaker on a knee-jerk basis merely because they are old without testing them first. Age is certainly a reasonable basis on which to presume that all the caps should be tested.

I agree with you that it would probably be worthwhile to try to out-think the designers of a speaker that showed signs of failure after only seven years. The possibility that a speaker may re-voice due to component changes is certainly less undesirable than a speaker that doesn't work at all, and if the speakers were of questionable worth to begin with and were obtained cheaply, there is probably nothing to lose by experimenting. But I would be more likely to just assume that the rest of the unit was designed and built with similar poor quality and replace the entire POS ASAP after that before something else blows. YMMV.

I think most 20 year old caps (perhaps even some caps that are 30 or more years old) will meet their original specs for capacitance if that is all you are measuring for. But, in my experience, it is rare to find caps older than 20 years in crossovers that measure good for ESR (Equivalent Series Resistance).

I will attach a picture of a bad cap. This one came out of a Klipsch crossover that was about 25 years old. Notice the top number. That is capacitance. The cap is a 2 uF so, the reading is pretty good. Now look at the bottom number. That one is ESR and reads about 68 ohms. So, with 68 ohms series resistance, almost no signal was going to get through this cap. Unless you can measure ESR, you are for the most part just wasting your time if you go through a bunch of crossover caps just testing for capacitance.

Bob Crites

gkimeng
11-20-2007, 09:22 PM
Very interesting, and I for one am taking note. If you have any good pics of such an old network with the caps showing up nicely, I'd like to see them. Also, would you please post details of how you tested the caps, and what instrument you used. I'm also interested if there were any tests involving actual signals, or were the tests for measured capacitance only? Best ... LORNE

If I'd known at the time that I might have a use for such pics someday I'd have taken them. :)

I've repaired/restored about a dozen pairs of speakers over the past 40 years or so, most of them ARs of different types, with a few KLHs, some private label boxes of unknown parentage and one JBL Ranger Paragon thrown in for variety. So my experience probably doesn't qualify as any kind of statistical sampling.

Test instruments varied from handheld VOMs with capacitance settings to really expensive stuff I had no idea how to use (someone else did the testing and I just helped).

In all the cases, the caps were tested because somebody (not necessarily me) thought there was something not quite right about the sound that might have been caused by bad caps, and the caps were either removed or just temporarily desoldered at one lead. Testing was for capacitance only. The only "signal testing" involved in most was with the ears of the same person who originally thought there was a problem, except for the JBL, which got tested and retested several times in an actual anechoic chamber.

Patterns of failure: the most bad caps were from the private label speakers (no surprise there). AR and KLH cap states seemed to correspond fairly well to the condition of the rest of the box (battered boxes, bad caps, babied boxes, good caps). The caps in the JBL, which was about 25 years old at the time, were bang on spec, not surprising since it had been meticulously maintained and had not been moved from its spot in a university alumni center (the same school where the anechoic chamber was) since the day it had been delivered. Didn't find one thing wrong with that one.

The only conclusion I can draw from my experiences is that the odds of any component in a speaker being bad depend on (a) original choice of components, (b) original build workmanship and (c) the kind of treatment the unit receives in use. Nothing surprising there, right?

gkimeng
11-21-2007, 12:51 AM
Unless you can measure ESR, you are for the most part just wasting your time if you go through a bunch of crossover caps just testing for capacitance.


Possibly, but if little or no signal is getting through the cap you ought to be able to tell something's wrong just by listening. I don't even bother to test the caps unless my ears make me think there's something wrong.

spkrdtr
11-21-2007, 06:14 AM
Possibly, but if little or no signal is getting through the cap you ought to be able to tell something's wrong just by listening. I don't even bother to test the caps unless my ears make me think there's something wrong.

Most old electrolytic crossover caps I test have ranged from 0.5 to over 1 ohm ESR. That's higher than they should be and, most likely were when new. That drifting gently softens the tweeter's output over time so it's hardly noticed, if at all.
However, when new caps with ESR'rs near or at 0 ohms are installed and the speaker fired up, the owner immediately notices a change, because it is a step change rather than a gradual one.
The question arises, at what point in the gradually escalating ESR curve is it time to replace old NPE caps? I don't think there is any hard and fast rule. My choice is >= 0.5 ohms. YMMV

BECtoo
11-21-2007, 07:58 AM
Most old electrolytic crossover caps I test have ranged from 0.5 to over 1 ohm ESR. That's higher than they should be and, most likely were when new. That drifting gently softens the tweeter's output over time so it's hardly noticed, if at all.
However, when new caps with ESR'rs near or at 0 ohms are installed and the speaker fired up, the owner immediately notices a change, because it is a step change rather than a gradual one.
The question arises, at what point in the gradually escalating ESR curve is it time to replace old NPE caps? I don't think there is any hard and fast rule. My choice is >= 0.5 ohms. YMMV

I think your choice of >= 0.5 ohms is a good value to declare bad. That seems to be the value that almost anyone will think of as an improvement in clarity at least when the cap is replaced. The crossovers I rebuild most often do not use any electrolytic caps, so this increase in ESR is not limited to electrolytics. I find that almost every film and foil cap in crossovers from the 70s has an ESR of around 0.5 to 1.0 ohms. Also, if the filter is a higher order, the values of ESR for each cap in series adds and replacement makes an even larger difference to the listener. I like to see ESR in new caps at a value of 0.05 ohms or lower and usually see that value at less than 0.03 in quality polypropylene caps.

Bob Crites

Pilot
11-21-2007, 08:55 AM
One thing that ought to be taken into account when replacing caps in crossovers with film caps is capacitor current. Most cap manufacturers publish the maximum current in their data sheets. Unfortunately, calculating the current involves a little differential calculus which is going to put a few folks off. You can get a rough idea by calculating the impedance of the cap and using Ohms law to find the current. For instance, my crossovers have 61µF caps at the bass end so I use 13 x 4.7µF in parallel so that I don't exceed the cap current.

Bryan

gkimeng
11-21-2007, 09:28 AM
Most old electrolytic crossover caps I test have ranged from 0.5 to over 1 ohm ESR. That's higher than they should be and, most likely were when new. That drifting gently softens the tweeter's output over time so it's hardly noticed, if at all.
However, when new caps with ESR'rs near or at 0 ohms are installed and the speaker fired up, the owner immediately notices a change, because it is a step change rather than a gradual one.
The question arises, at what point in the gradually escalating ESR curve is it time to replace old NPE caps? I don't think there is any hard and fast rule. My choice is >= 0.5 ohms. YMMV

Ultimately, I think the bottom line is that if they're your speakers and you're planning on keeping them you can do what you want, and if you think changing out anything improves the sound the only opinion that matters is your own. Of the dozen or so pairs of speakers I've been inside of over the years, only two pairs belonged to me, and I'm quite happy with the way they sound with all of their original electronics.

But if you're working on someone else's speakers, or restoring something of value with the intent of resale, owners or prospective buyers may not be very enthusiastic about you changing things they don't perceive as broken unless you're a pro with an established reputation for successful repairs/restorations/mods. Coincidentally, here is something recently said to me by someone who I think would be reasonably well-known to readers of this forum (not named here because it's a quote from a private email and I haven't checked to make sure it's ok to use it with attribution):

"I could tell you about a customer that sent a pair of AR 90 for us to completely rebuild the crossovers after some hobbyist thought he knew more than AR or the customer that paid $1000 for a pair of AR-LST and then paid us $500 to make them right."

lorne
11-21-2007, 05:58 PM
But if you're working on someone else's speakers, or restoring something of value with the intent of resale, owners or prospective buyers may not be very enthusiastic about you changing things they don't perceive as broken unless you're a pro with an established reputation for successful repairs/restorations/mods.You definitely have a point, and we can assume that most seasoned hobbyists have faced this dialemma even as they KNOW that modifications — or better still, UPDATES — can produce a better instrument.

gkimeng
11-21-2007, 06:35 PM
You definitely have a point, and we can assume that most seasoned hobbyists have faced this dialemma even as they KNOW that modifications — or better still, UPDATES — can produce a better instrument.

When I buy things I plan on keeping them forever, so there's never a hobbyist dilemma for me (my wife is another story). If I'm working with something that belongs to someone else, that's also easy, let them decide and do what they want. If I were ever to buy something with the intent to resell it, I would go the "preservation and restoration" route, and mod nothing unless it was something with an established pedigree. For example, I don't think any AR turntable owner ever went wrong with a George Merrill mod.

totem
12-09-2007, 01:38 PM
Its been a learning experience reading the comments and suggestions in this
sticky
As far as the cap,s and the various options, I now have an understanding of what options are available.
I have a rather "busy" looking crossover out of a 3 way EV Sentry series,
of witch I neglected to photo prior to assembling so I have a link to DaWoofers
posted pic.
http://www.audiokarma.org/forums/attachment.php?attachmentid=56782&d=1186440854

There are 3 np 30uf 70 volt caps that I intend to change due to their age.
The rest of the crossover Is what I need a little help on.

Are there additional "while I am in there" things that anyone can ID in the pic
that I may want to look at upgrading.

There seems to be a harshness in the upper mids, lower treble area that I want to deal with.

I am not looking to do a total rebuild or redesign at this stage, but an
upgrade.

spkrdtr
12-09-2007, 06:57 PM
Its been a learning experience reading the comments and suggestions in this
sticky
As far as the cap,s and the various options, I now have an understanding of what options are available.
I have a rather "busy" looking crossover out of a 3 way EV Sentry series,
of witch I neglected to photo prior to assembling so I have a link to DaWoofers
posted pic.
http://www.audiokarma.org/forums/attachment.php?attachmentid=56782&d=1186440854

There are 3 np 30uf 70 volt caps that I intend to change due to their age.
The rest of the crossover Is what I need a little help on.

Are there additional "while I am in there" things that anyone can ID in the pic
that I may want to look at upgrading.

There seems to be a harshness in the upper mids, lower treble area that I want to deal with.

I am not looking to do a total rebuild or redesign at this stage, but an
upgrade.

If you have a good LCR meter you should look at replacing those mylar caps also, measure those adjustable/fixed resistors and replace with like values in non-inductive, audio grade types and measure the inductance and DC resistance of those coils and replace with like values in air core types. This will run you some money though.
Your best bet is to draw a schematic and attack those components in series with the tweeter and mids first. re-assemble and listen for awhile before deciding if more compents need changing.
Good luck.

lorne
12-09-2007, 07:08 PM
Cool. My 2 cents worth: I'd change out the old electros for some appropriate film caps and leave it alone ... see what they sound like. The new caps *may* restore some balance in the audible spectrum that has been lost. The freshened sound may have a more pleasing effect. If the harshness is an inherent part of the drivers, film caps will surely not improve anything. They may even reveal more of the same. Of course you also have the option of putting some nice modern NP electrolytic types in too.

It looks like there is a gain or roll off switch with two or three positions ...?? If so, get into that carefully with some switch cleaner and a Q-tip. Some people like to rewire or bypass in order to get a flat setting. But I'd just be sure the switch is in top condition and see what it sounds like in different settings. Such switches allow you to adjust the speaker voicing to different rooms. Sometimes I wish I had left some of my switch circuits in place ... or rather just substituted a new and better switch.

EDITED LATER: I just reviewed Carl's message. I think I'd go with his advice for sure.

totem
12-09-2007, 11:53 PM
Thanks Carl and lorne for your recommendations.
Just to confirm from the pic posted I am on the same page in regards to iding
the various parts.

There are 3 dark caps 30uf 2 on bottom center 1 at the top
2 mylar caps, 1 yellow and 1 blue
6 coils
2 brown rods on the left? note sure on these
1 or 2 resistors on top of the 4th coil?

Give me a piece a veneer and I am much more comfortable!

spkrdtr
12-10-2007, 06:56 AM
Thanks Carl and lorne for your recommendations.
Just to confirm from the pic posted I am on the same page in regards to iding
the various parts.

There are 3 dark caps 30uf 2 on bottom center 1 at the top
2 mylar caps, 1 yellow and 1 blue
6 coils
2 brown rods on the left? note sure on these
1 or 2 resistors on top of the 4th coil?

Give me a piece a veneer and I am much more comfortable!

Hey, we ought to pair up. I'm more comfortable with a crossover than veneer!
I believe those brown rods you refer to are variable resistors. They look just like the ones Peter Snell used to fine tune his early Snells to match SPL's of components. You can measure what the resistance they are set to and purchase the resistors I mentioned to equal those values.
Again, if you don't have an LCR or know someone who does and are able to draw a schematic, I don't recommend going hog wild with an upgrade. Just do the caps as I and Lorne have suggested.

bowtieman427
12-16-2007, 02:41 PM
What are opinions on Dayton Precision 1% Metallized Polypropylene Capacitors. I am currently considering using them on my rebuild.
Thanks
Jim

AU20K
01-08-2008, 02:29 PM
Thanks in advance.

AU

Face
01-08-2008, 03:23 PM
There's a tiny blub here: http://www.soniccraft.com/sonicap_gen_2.htm
The shorter lead is shield.

BECtoo
01-08-2008, 04:32 PM
Well, I should be embarrassed to be asking this, but I don't embarras that easily. Can/will anyone tell me; 1, if Sonicaps are polarized? and 2. if they are, wich end is which? I got Forte upgrade from B Crites and i thought I was setting neg in line until I looked at them with a magnifier and saw that the little neg thingie is actually the copyright stamp. Hmmm after 40+ years I realize I don't know S--t from Shinola about some things.

Thanks in advance.

AU

It does not matter at all which way you connect the Sonicaps. After all, all signals in a crossover are AC. Not possible for any capacitor used there to have a polarity since all signals in there alternate between + and -.

Bob Crites

AU20K
01-09-2008, 07:40 PM
Great, Thank you both for the help.

shacky
01-12-2008, 11:05 AM
Just recapped and refoamed pair of EPI 201's. They sound wonderful but I can't say exactly how recap changed sound as surrounds were the bigger problem.

Would like to measure old 10 uF caps but do not have equipment.

Anyone willing to have me send old caps to you for measurement - then disposal?

spkrdtr
01-12-2008, 11:58 AM
Just recapped and refoamed pair of EPI 201's. They sound wonderful but I can't say exactly how recap changed sound as surrounds were the bigger problem.

Would like to measure old 10 uF caps but do not have equipment.

Anyone willing to have me send old caps to you for measurement - then disposal?

I'll volunteer. I have capacitance and ESR testers.
Write me privately for address.

shacky
01-25-2008, 11:23 PM
Here are results from EPI 201 original caps. Thanks Carl!!!

capacitances: 9.5m 9.7, 9.9, 9.97
dF@ 1 kHz: 6%, 7%, 7.7%, 7.7%
ESR's: 1 ohm, 1 ohm, 0.9 ohm, 1 ohm

spkrdtr
01-26-2008, 10:45 AM
Here are results from EPI 201 original caps. Thanks Carl!!!

capacitances: 9.5m 9.7, 9.9, 9.97
dF@ 1 kHz: 6%, 7%, 7.7%, 7.7%
ESR's: 1 ohm, 1 ohm, 0.9 ohm, 1 ohm

Shacky: The units on the capacitances should read uF.
BTW, they were labeled as 10 uF caps, so not much drifting on that property. However, ESR is another story.

shacky
01-26-2008, 10:51 AM
Carl,

Sorry about that. And thanks for listing original cap value of 10 uF. I should have indicated that for those not familiar with EPI.

Can you explain why the ESR is a problem?

Jim

spkrdtr
01-26-2008, 02:31 PM
Carl,

Sorry about that. And thanks for listing original cap value of 10 uF. I should have indicated that for those not familiar with EPI.

Can you explain why the ESR is a problem?

Jim

ESR means Equivalent Series Resistance. It is a normal property of all caps. Electrolytics are, by their inherent design, prone to have excalating ESR as they age due to changes in the electrolytic paste.
A new cap should have a very low ESR <<< 0.25 ohms. As NPE's age, ESR creeps up and up and in doing so, begins to act like a valve, gradually shutting off the voltage from reaching the tweeter or midrange thus reducing the highs those drivers are capable of. It basically begins to take on a secondary role; that of an added series resistor.
So, it's important to speaker 'health' to maintain a low ESR in order to keep the mid and high frequency performance output the same as when new.
Changing out old NPE's and replacing with FF types is a good way to prevent the problem from recurring.
I have discussed that in previous posts on this thread.

The Reverend
01-30-2008, 03:39 PM
Hello,

I just bought a pair of Pioneer CS-R700 speakers and I a want to recap them. The crossover network is attached below. What I am wonderig is, if useing all Solen caps, if these are good choices:

35uF = 33uF||2uF (SOLEN-54968, SOLEN-55875)
14uF = 12uF||2uF (SOLEN-51556, SOLEN-55875)
18uF (SOLEN-62370)
1.3uF (SOLEN-62361)

All parts are from partsconnexion. Are there better ways to do this than paralleling for the 35 and 14?

spkrdtr
01-30-2008, 04:40 PM
Hello,

I just bought a pair of Pioneer CS-R700 speakers and I a want to recap them. The crossover network is attached below. What I am wonderig is, if useing all Solen caps, if these are good choices:

35uF = 33uF||2uF (SOLEN-54968, SOLEN-55875)
14uF = 12uF||2uF (SOLEN-51556, SOLEN-55875)
18uF (SOLEN-62370)
1.3uF (SOLEN-62361)

All parts are from partsconnexion. Are there better ways to do this than paralleling for the 35 and 14?

The most important caps you have are the mid (18 uF) and the tweeter (1.3 uF). My suggestion is to save on the parallel caps (35 and 14) by getting NPE's from Parts Express and buy some better caps for the tweeter like Jantzen Superior Series - also from Parts Express. You can get a 1.0 and 0.33 Jantzen for about $18 each set. Stick with the Solens for the mids.

The Reverend
01-30-2008, 06:20 PM
So from PE, should I parallel the 12uF, 15uF, and 8uF to make the 35uF? No issues with three caps in parallel with tolerances and such? The 14uF would be the 10uF and 4uF. From what I understand the woofer caps are quite as important in terms of fidelity, I mean, look what is coming out the woofer.

lorne
01-30-2008, 08:01 PM
I bow to superior expertise in this area, but in partial answer to your question: I have not hesitated to use parallel caps in X-over networks. For example, it worked brilliantly in my Tannoys, and perhaps saved me money because I was able to use more affordable, industrial film caps that incidentally were not sized for the application — and they were expense enough.

spkrdtr
01-30-2008, 08:12 PM
So from PE, should I parallel the 12uF, 15uF, and 8uF to make the 35uF? No issues with three caps in parallel with tolerances and such? The 14uF would be the 10uF and 4uF. From what I understand the woofer caps are quite as important in terms of fidelity, I mean, look what is coming out the woofer.

I would think for your Pioneer speaker, paralleling with NPE's in the woofer section is the right way to go. Multiple parallels are okay also. A very well regarded speaker designer, Peter Snell, of Snell Acoustics used to parallel numerous 4 uF caps to get large values in some of his early classics.

The Reverend
01-30-2008, 08:29 PM
Great, I will definitely do this. Thanks to all for the tips.

HiFiSoundGuy
02-07-2008, 05:42 PM
I'm waiting for the all new SoniCap Gen. 5's to come on the market so I can recap my Sansui sp-5500's.........:smoke: http://www.10audio.com/sonicap_oimp_multicap.htm

Face
02-15-2008, 01:44 AM
I recapped my Tannoys with Sonic Caps the other night. Upon initial startup they sounded terrible. About 15 hours of play time later they're starting to come around.

Thespeakerdude8
02-18-2008, 12:25 PM
Great thread here. I had a question about paralell values.

I want to recap my sansui sp-1500's, but I noticed there are some paralell caps in there.

For instance, 2uf BP with a .5ufBP across it. Why did they do this? Was it to lower ESR and allow hf to pass better across the cap, or was it simply to create a 2.5uf cap because none were available to them? Obviously, you can order just about any value of cap nowadays so wouln't it just be better to replace both with a 2.5uf cap? etc etc for the other caps as well.

Lux Man
02-19-2008, 08:29 PM
I don't have the for sure answer for you, but unless someone is intimately familiar with that circuit it more likely has to do with a supply(inventory) issue.

In the Braun 810's that I recapped today they used 2-4.7's in place of a 10uf. And I am sure it had to do with the increase in buying power since they also used another 4.7uf in the crossover. It lowered their cost on all the 4.7's and reduced the number of items on the BOM.
I used to sell caps to Magnepan and they chuckled at the thought that some of their customers thought 2 caps in parallel sounded better than one larger one.
BTW, in my 810's I just used Solens. While having just listened for a couple hours I would say the effort was worth it, for two reasons. First, now I don't have to wonder anymore whether they need it.(peace of mind) Secondly, I believe there is in fact an improvement, primarily in the high frequency response which I think has helped to bring greater clarity. It was pretty painless, about 15 minutes per speaker and $30. I got my money's worth which was just a little bit more preformance from an already decent speaker.

Doctor B.
03-14-2008, 11:20 AM
Thanks to everyone who has contributed to this thread. It has been very helpful to me.

I just recapped my Sansui SP-3000 speakers and I am very pleased with the results.

I am hearing more high frequency response and the bass is more clearly defined. I am hearing more percussive sounds like the “slap” of bass strings in jazz music and more of the harmonics of classical guitar strings than I had noticed previously. With organ and choral music I am noticing more of the reverb and overtones in the performance space. With chamber music and classical guitar, it sounds more like the instruments are in the same room with me.

I used Dayton Precision 1% Metalized Polypropylene caps, which were $54 for the ten caps at Parts Express. I considered using the regular Dayton polypro’s ($30), Solens ($46), and ClarityCap PX Range ($52). The Precision caps have a 1% tolerance versus 10% for the regular Daytons and 5% for the Solens and ClarityCaps. I figured that the quality control that goes into making something with a 1% tolerance just might be worth the extra money.

SP-3000s haven't received very good reviews from some Akers because of weak bass response. I wondered whether investing $54 in caps was “trying to make a silk purse from a sow’s ear.” I’m sure there are better speakers out there, but for the moment with only $82 for the speakers and $54 for the caps invested I think I’m getting my money’s worth. I like the walnut veneer, the wood lattice grills, and the solid construction of the cabinets along with what seems to me to be good musical sound.

Before the recap, I had hooked a subwoofer and a pair of supertweeters to the "B" output of my SX-1050. I would click these on whenever I wanted to hear more top and bottom end. With the new caps, I find that the Sansuis are so much brighter that I don't need the supertweeters and so I've disconnected them from the system. I think I’ll keep the sub for those times when no one else is at home and I want to shake the house. :yes:

For anyone wanting to recap their SP-3000s, these have a five-way crossover. There are five caps per speaker: two 15μF and one each 3.3μF, 2.2μF, and 0.47μF. The Dayton caps are larger than the old electrolytics, but there is plenty of room for them on the board. The crossover is easy to follow and easy to work on. It's just a matter of desoldering the old caps, prying them up off the board, soldering in the new caps and hot-gluing them down so that they don't rattle around. I broke a couple of the mounting tabs while trying to desolder the old caps. Wrapping and soldering wires directly to the cap leads solved the problem. Following advice on this forum, I didn’t replace the two 3Ω resistors. I did give the L-pads a good cleaning with Deoxit.

I’ve attached a couple of pictures: first of the crossover with the original caps and second with the new caps.

Tripqzon
03-14-2008, 03:54 PM
Glad to hear the recap was a success. Now you can enjoy those speakers the way they were meant to sound. :banana:

HiFiSoundGuy
03-26-2008, 06:06 PM
The point of diminishing returns start kicking in quick for capacitors and your pay big money on that very small improvement that the best capacitor will give you. Here's some tests on capacitors www.humblehomemadehifi.com/ <(Click on Cap Test) and the best deal going right now for the money is the Jantzen Audio Superior Z-Cap from Parts Express

Lux Man
03-26-2008, 09:15 PM
Just FYI,

I thought I'd replace the caps in my ADS L910's. I used Solens Fast caps. The result was horrible. The highs were gone and the midrange was nasely. I couldn't believe it so I put in some jumpers so I could switch back easily. The new caps were horrible compared to the 30 yr. old EVOX box cap.. Granted I do not know if it's just Solens or not but I'm not doing any more experimenting to find out. The lesson here for me is, a cap is not a cap is not a cap. I do suspect Solens is the issue but I'm going to be content with what I have for now. So don't just assume a new cap is going to be better or as good as the old one. BTW yes I used the same value caps for replacements.

BECtoo
03-26-2008, 10:06 PM
Just FYI,

I thought I'd replace the caps in my ADS L910's. I used Solens Fast caps. The result was horrible. The highs were gone and the midrange was nasely. I couldn't believe it so I put in some jumpers so I could switch back easily. The new caps were horrible compared to the 30 yr. old EVOX box cap.. Granted I do not know if it's just Solens or not but I'm not doing any more experimenting to find out. The lesson here for me is, a cap is not a cap is not a cap. I do suspect Solens is the issue but I'm going to be content with what I have for now. So don't just assume a new cap is going to be better or as good as the old one. BTW yes I used the same value caps for replacements.

Something really strange going on there.

Face
03-26-2008, 10:32 PM
Solen caps are bright if anything, something is not right there at all.

Did you allow them any time to break in? I found most replacement caps need at least 10 hours of burn in to get a idea of what you're in for. Some call for up to 300 hours.

Lux Man
03-27-2008, 09:34 AM
I am with both of you on this-I woke up in the night thinking no way. So this morning I put one set back in- same thing. These are 4.7uf's the one to the tweeter is in series the one to the mid is in parallel. They are c2 and c4 if you look at the schematic on the ads sticky. I recently re-capped the L810's with Solens and they did brighten just a touch which was fine but this is much different. I'll tell you what my two tests are-on the Diana Krall, "the Look of Love" track 3 in the very beginning there is a triange/chime, well with the Solens in there it is barely audible, with the original caps in it rings clear and has a sustain to it. The other test is a female vocal, Eva Cassidy I use alot for tests and her voice sounds nasaly with the Solens. If the Solens needs to be broken in and the best scenario is they might bring back the sound I have now, well I am not sure of the point of that excersize.

Lux Man
03-27-2008, 11:16 AM
I will admit I gave them no time to break-in, the sound was so strikingly bad. But as I mentioned above, in the case of the Solens what compelling reason do I have that they will eventually surpass what I have now? Unless you tell me that even the best capacitors often sound very very inferior in the initial stages of burn-in. In my case the reason to replace wasn't that I detected any unsatisfactory sound issue, it was just this disease I have that doesn't allow me to leave stuff alone when there is any chance of an upside. And then with having re-capped the L810's with immediate positive results- this was just so in contrast, I just had to pull them.

I will look forward to your further comments-

spkrdtr
03-27-2008, 11:49 AM
I am with both of you on this-I woke up in the night thinking no way. So this morning I put one set back in- same thing. These are 4.7uf's the one to the tweeter is in series the one to the mid is in parallel. They are c2 and c4 if you look at the schematic on the ads sticky. I recently re-capped the L810's with Solens and they did brighten just a touch which was fine but this is much different. I'll tell you what my two tests are-on the Diana Krall, "the Look of Love" track 3 in the very beginning there is a triange/chime, well with the Solens in there it is barely audible, with the original caps in it rings clear and has a sustain to it. The other test is a female vocal, Eva Cassidy I use alot for tests and her voice sounds nasaly with the Solens. If the Solens needs to be broken in and the best scenario is they might bring back the sound I have now, well I am not sure of the point of that excersize.

Your 3rd sentence above suggests you used 4.7's for both the C2 and C4. Is that what you did? please confirm.
The schematics for the 810 and 910 I read show 6.8 uF caps for C4 on the tweeter cap and 4.7 for the parallel mid cap.
Also curious as to why didn't you change out C3, the series mid cap?

Lux Man
03-27-2008, 01:32 PM
Excellent questions. Guess what? Not all the documents are correct when it comes to the schematics. This pair of L910's were bought in 1980, according to the documents provided with them they were very early because the letter from ADS states the manual is not ready yet but here's how to hook them up. So with that said, the schematic says C4 is a 6.8uf but in mine it is a 4.7uf and yes it is the original Evox cap. I know other L910's have the 6.8uf because my other pair does. I have come to the conclusion based on other L910's and my own that there may not be clear cut versions but in fact a number-ADS was making changes on the fly so to speak. These are Series 1 (the original)but I have seen other Series 1's with the 6.8uf used for C4. The other pair I have are Series II.

Why didn't I change out C3? These are being bi-amped and when they are bi-amped C3 is bypassed, as well as R2. C1 and L1 are also bypassed when bi-amped but that has nothing to do with this.

Lux Man
03-27-2008, 01:47 PM
Actually I should retract a part of a statement above the other Series I, I have seen also used a 4.7uf for C4 but in that one C3 was not a single cap(13.6uf) but 3 box caps. in parrallel. Mine by the way is a single 15uf film /foil axial lead cap not a 13.6 as the schematic said. I have not seen a 6.8uf used in a series 1 so far. The reason I am speculating is, that the series 1's have 1" soft domes and the series 2, have 3/4" tweeters. That's my speculation until I see different.

Lux Man
03-31-2008, 09:59 AM
To conclude my exercise here, I did end up putting the Solens back in and let them play for 5 hours or so, when I returned the high frequency was there that had been missing. I will admit I still don't undersatnd why a capacitor of this type would require burn in for any period of time. When I think of all the equipment manf. out there I rather doubt they burn it all in for hours and hours, but maybe I am wrong.

I concluded that the Solens in these speakers did not improve any aspect that I could tell and maybe still detracted a slight bit, consequently I put the originals back in the ADS L910's.

dr x
04-20-2008, 08:44 PM
Is volume a consideration when "breaking in" new caps?

I have a pair of Advent 5002's that will be getting a re-cap pronto. There is a 3 ohm 10% 10w resistor in line with the tweeter. It tests fine. However, there is a bad cap (50v 7mfd) that needs to be replaced before the tweeter works again. Would you recommend replacing the resistor along with the caps or just leave the resistor alone?

Doctor B.
04-22-2008, 09:33 PM
Would you recommend replacing the resistor along with the caps or just leave the resistor alone?

I asked the same question recently and the consensus answer was to leave the resistors alone.

If I remember correctly, resistance is just resistance, and if an old resistor still tests within tolerance it ought to be okay. Caps are a different story. While old caps may test within tolerance for capacitance, with age they can increase in resistance and that isn't good.

Somebody straighten me out if I haven't got this right.

Stanga
04-23-2008, 06:34 AM
It depends on the material. Ceramic and metal can be left untouched. Carbon types are however noisy lots that can be improved upon by changing them for ceramic. I have had sound problems changing carbon to metal on some speakers for some reason, but ceramic solved the problem. I also found that uprating the wattage on the resistors if you play music loud regularly also made a difference.
Off course perhaps, but I even bolted my cross over on to a heatsink. It makes a difference once you have had the speakers playing for an hour or so.

NotSure
05-06-2008, 07:14 AM
I feel bad about this, I have not read through the whole thread, something I would not normally skip. I promise I will read through the other 10 pages as soon as I can. I am just a little pushed for time as my other half is due sometime in the next week and recapping needs to work around her schedule.

I have a pair of Mission 70MkII ('88 vintage) and I want to recap them, and hopefully pass on the information once I have used mine as guinea pigs. They only have the two caps per crossover, both are "Micro" brand, bi directional 3.3 uF 50v.

I understand (thanks to ESP) that bi directional caps are cheap and prone to fast degradation. Can I replace these with non bi directional (uni directional?) caps? If I can, which way around do I install them? And does anyone have any recommendations? I am not wanting to get the absolute best caps, but a reasonable priced upgrade would be good.

NotSure
05-07-2008, 07:58 PM
I have had time to read through the rest of the thread, and have answered some questions, but have a new question. I can use "polarised" (yay, I no longer sound like an idiot) caps in either direction.

My new question is that since there are two caps in each crossover, I am assuming (please correct me if I am wrong) that one is for the tweeter roll off and one is for the woofer roll off. Will it adversely affect the sound if I accidentally install a cap one direction for the tweeter and the other direction for the woofer? I know that noise cancellation techniques work on out of phase sound waves. I can clearly make out the direction of the earth for one of the caps, but not the other.

Since a reply has take a while, I am off today to get some Solens. The importer is nearby and they are not a horrendous price. That and I can't find anyone nearby who sells any of the other brands listed in this thread.

davesnewTT
05-08-2008, 09:18 AM
hey there notsure,

polarised caps block current in one direction. the music signal to your speakers is alternating current (AC), in two directions. so you can't use polarised caps in there. you need to get non-polarised or bipolar caps, that pass current both ways. since they are not polarised it doesn't matter which way you put them in.

geoff727
05-09-2008, 03:30 AM
NotSure,
Here's what I did on my Mission 70 MkII's. SOLEN's for the series tweeter cap and the woofer shunt cap. And a Mills MRA5 resistor for the tweeter circuit. Left the woofer cored-inductor alone, as I currently have no way of measuring inductance or DCR of the coil.

geoff727
05-09-2008, 03:31 AM
Here's the picture of it.

NotSure
05-09-2008, 07:04 AM
NotSure,
Here's what I did on my Mission 70 MkII's. SOLEN's for the series tweeter cap and the woofer shunt cap. And a Mills MRA5 resistor for the tweeter circuit. Left the woofer cored-inductor alone, as I currently have no way of measuring inductance or DCR of the coil.

Thanks for the information. It looks like I have the same Solens you got, I have not installed them as I have been busy seeing to my wife and new son... In fact we were in the car ab out to go buy the Caps when she went into labor... so the Caps had to come second... it DID require a five minute conversation about priorities. No SWMBO did not try to convince me to give up my dream of new Caps, she was the one wanting to go get them.


So why did you add the Mills MRA5 resistor?

NotSure
05-09-2008, 07:10 AM
hey there notsure,

polarised caps block current in one direction. the music signal to your speakers is alternating current (AC), in two directions. so you can't use polarised caps in there. you need to get non-polarised or bipolar caps, that pass current both ways. since they are not polarised it doesn't matter which way you put them in.

Thanks for the headsup. I read someone else in this thread who seemed to indicate it was OK to use polarised. The Solens I was looking at were bi-polar by accident anyway, but I double checked before paying for them thanks to your advice.

geoff727
05-09-2008, 01:48 PM
So why did you add the Mills MRA5 resistor?

I replaced the original sand-cast resistor that was in there (a 2.2 ohm I believe). Sonically, it's a better resistor. I get the feeling that our two Mission 70's have slightly different crossovers. I think yours might be a bit later variety than mine.

geoff727
05-09-2008, 01:58 PM
I have a pair of Mission 70MkII ('88 vintage) and I want to recap them, and hopefully pass on the information once I have used mine as guinea pigs. They only have the two caps per crossover, both are "Micro" brand, bi directional 3.3 uF 50v.



Yep, we definitely have 2 different variations of the "MK II" speaker. So Mission must have changed drivers somewhere in the line. Here's a picture of the original crossover for mine, located on the back of the binding post plate. I rebuilt them at the bottoms of the enclosures for ease of access into the box.

NotSure
05-09-2008, 03:59 PM
Yep, we definitely have 2 different variations of the "MK II" speaker. So Mission must have changed drivers somewhere in the line. Here's a picture of the original crossover for mine, located on the back of the binding post plate. I rebuilt them at the bottoms of the enclosures for ease of access into the box.

Yes they did change tweeter in 88 or earlier. They went to a SEAS tweeter. It was supposed to tame the treble a little. I had only ever heard the SEAS version when I purchased my first pair. They made one last change that I know of later, but it was only adding a vinyl sheet to the inside of the front baffle. My crossovers do not have resistors, the caps are all 3.3 uF, but the rest of the crossover seems the same.

YamahaFreak
05-10-2008, 06:06 PM
I've read through ~one quarter of this thread and found some valuable information, but I think I should still ask, so here goes... *deep breath*

I have a pair of Yamaha NS-A100's that I'm considering recapping. They are about 22 years old (1986) and I DO notice some problems with the sound that are constants regardless of what I power them with:

1. Either the left midrange is quieter than it should be, or the right midrange is louder than it should be

2. The right tweeter definitely seems to lack some of its lower frequencies(lower than ~8,000 cycles). The right one seems fine. Again, this might be the opposite, with too much lower frequencies leaking into the left tweeter.

So, does this sound like I need a recap? They are simple crossovers, with an electrolytic in the positive line of each mid and tweet.

EDIT: Forgot to mention that all drivers are cones, if it matters.

Harvey/ Ga
05-13-2008, 10:36 PM
I've read through ~one quarter of this thread and found some valuable information, but I think I should still ask, so here goes... *deep breath*

I have a pair of Yamaha NS-A100's that I'm considering recapping. They are about 22 years old (1986) and I DO notice some problems with the sound that are constants regardless of what I power them with:

1. Either the left midrange is quieter than it should be, or the right midrange is louder than it should be

2. The right tweeter definitely seems to lack some of its lower frequencies(lower than ~8,000 cycles). The right one seems fine. Again, this might be the opposite, with too much lower frequencies leaking into the left tweeter.

So, does this sound like I need a recap? They are simple crossovers, with an electrolytic in the positive line of each mid and tweet.

EDIT: Forgot to mention that all drivers are cones, if it matters.


Like you, I've read thru the recap threads, and finally decided to bite the bullet. I ordered Dayton 5% poly caps for my Smaller Advents and Wharfedale W-60E's. Both are over 30+ yrs old.

I wasn't too impressed with the 60E's when I first got them, but let them play softly for a few days, and sprayed Deoxit into the mid and tweeter pots, and things improved...still not like I remembered my old 60's (new in '63).

I recapped one of the 60E's today, and was astounded at the improvement..even to my tin ears!! :music: I had daughter's Polk 10A's next to the 60E and the 10A's were definitely better in the bass then the 60E...BUT NOT NOW!! Makes me wonder how much of an improvement the Solens or Jantzen caps would have been :scratch2:

Go for it...unless getting at the caps is a royal PITA :thmbsp:

YamahaFreak
05-13-2008, 11:44 PM
Not too tough to get at, just first-order in-line. The hard part for me will be deciding how to attach the new ones to the wires. :headscrat

NOHDjunkie
05-18-2008, 12:11 AM
A quick question for the Re-capping gurus.

I have a new (to me) set of Cerwin Vega D9's. They sound great but to get the bottom end going I need the loudness button engaged and to crank up the bass knob.

With the treble and bass at 0 (flat) they are really anemic.

Crank up the bass and they rock. Is this an old crappy cap problem?

Thanks

Scorpion8
05-18-2008, 01:34 AM
Could just be your placement. That affects bass more than anything else.

NOHDjunkie
05-18-2008, 02:14 AM
Could just be your placement. That affects bass more than anything else.

Nope, not placement. Three different rooms three different amps.

NotSure
05-18-2008, 04:13 AM
OK, I have had time to recap one of my Mission 70 MkIIs (1988 vintage). I replaced the Micro bi-polar 3.3 uF 50v caps with Solens bi-polar 3.3 uF 400v caps.

I did a sound test and I have to say that the caps were 100% OK before I started. There is absolutely no difference from new. So I would have to recommend that for the next few years at least, late vintage 70 MkIIs should not need this upgrade.

The one sound improvement there is, is to fix one small problem this model of speaker has had since new. Every pair I have owned have had this problem. There is a brief moment during very hard to play bassy passages that these speakers distort. It is approximately 10-15 jiffies (yes, jiffies are a measurement of time... 10-15 = approximately 1/6th - 3/12ths of a second... though jiffies differ in length depending on the frequency of your power supply) in duration during dramatic passages. The Solens have completely removed this tiny but significant distortion.

So if anyone else comes up with a pair, and is considering new caps, hold off for now, unless you want better than new performance.

Harvey/ Ga
05-19-2008, 10:14 PM
Well, I finished re-capping the Wharfedale W-60E's and The Smaller Advents. I'll leave the RS-2001's as they are...for now.

I used the Dayton DMPC polypropylene caps. The W-60E's really came alive after capping. There wasn't as big an improvement in the Smaller Advents, but I just did them a few hours ago.

I considered the Solens..and maybe I should have spent the extra $19 for them, because of the improvement in the '60E's, but being retired and a bit tin eared, I thought that I wouldn't hear the difference :sigh:

Once I start using the RS-2001's more often, I'll do them. All told, I'm a happy camper :banana::yes:

Harvey/ Ga

YamahaFreak
05-21-2008, 03:15 AM
...but are they appropriate? I have one pair each: Oil-filled 2.2 mF @ 50V and electrolytic 5 mF @ 150V(replacing 4.7 @ 50, is this appropriate?) I haven't heard of anyone using oil caps; I was told by my boss that they won't deteriorate, but how are they for sound? :scratch2:

Harvey/ Ga
05-21-2008, 10:59 PM
...but are they appropriate? I have one pair each: Oil-filled 2.2 mF @ 50V and electrolytic 5 mF @ 150V(replacing 4.7 @ 50, is this appropriate?) I haven't heard of anyone using oil caps; I was told by my boss that they won't deteriorate, but how are they for sound? :scratch2:

The 5uf for the 4.7uf should be OK...I had to do the same for my 8uf...got an 8.2uf. Sound is beautiful...made the W-60's sing like new :banana::banana:

Can't say whether the oil filleds would be a good replacement. I don't think that they were made for audio use. The internal resistance (reactance??) may be too different. GordonW is our resident speaker fixer/designer and may be able to shed more light on it for you.

It would be interesting to use them in one speaker and see how they sound.

Harvey/ Ga

atticusdog
05-21-2008, 11:10 PM
Hello everyboby What caps do you guys suggest for recapping pioneer hpm 100s? if possible would like to "warm" up the sound a bit .Thanks.Dave

YamahaFreak
05-23-2008, 12:10 AM
It would be interesting to use them in one speaker and see how they sound.
Harvey/ Ga

I might try that. :yes:

Spalls
05-23-2008, 12:54 AM
After reading this and other threads regarding re-capping, I went ahead and recapped of the crossovers for my two sets of Speakerlab speakers: my 1978 .1s, the 1980 passive subwoofer, and a pair of S11s circa 1983. I used basic electrolytics from Parts Express in all of them, and also piggybacked some 0.01uF AudioCaps in the .1s. Wow - what a difference! I am hearing fingers plucking strings like never before, every breath that Nora Jones takes, and the vibes in Dave Gruisin's take on Thad Jones' A Child is Born just fill the room. Thanks to all of the AKers who have contributed their expertise and experience!

Harvey/ Ga
05-23-2008, 09:52 AM
I might try that. :yes:

Please do!! :yes:
I really didn't think that replacing the caps would do much good...and if I had at first recapped my Smaller Advents, that would have been the case...altho I _do_ hear a slight difference.

It was with the W-60E's that I heard a large improvement in sound. :banana:
Perhaps the English caps of the late 60's weren't as good as the American caps of '73 when my SA's were made.:scratch2:

Let me know how it works for you.

Harvey/ Ga

Jon S
06-10-2008, 11:01 PM
OK, I am about to jump into recapping my Polk Monitor 10Bs... I got the caps, and I have a couple of questions...

1. I have to "stack" (parallel) a couple of caps to meet the value required. Do I need to glue the caps together?

2. What is the reason putting glue in the first place? All the caps in the crossover are glued to the board and I figure there's got to be a reason for that.

3. If required, do I have to use a heat glue gun or will plain old silicon glue work?

Thanks in advance...

Face
06-10-2008, 11:08 PM
OK, I am about to jump into recapping my Polk Monitor 10Bs... I got the caps, and I have a couple of questions...

1. I have to "stack" (parallel) a couple of caps to meet the value required. Do I need to glue the caps together?

2. What is the reason putting glue in the first place? All the caps in the crossover are glued to the board and I figure there's got to be a reason for that.

3. If required, do I have to use a heat glue gun or will plain old silicon glue work?

Thanks in advance...
Hmm... this screen name is familiar. :scratch2: :D

You should glue caps to each other and/or to the board to prevent them from vibrating. You should see how much glue Tannoy used on some of their crossovers, you would think they owned a glue factory.

I use a cheapo glue gun, works great.

geoff727
06-13-2008, 11:20 PM
Those poor Polk crossovers. They take so much sonic abuse from the acoustic energy inside those enclosures used to drive the passive radiators, with a small amount of internal damping. I just finished a pair of 5Bs' crossovers with ClarityCap's, and with the size of the 34uf combo, I affixed them with plenty of hot glue, a very stable and tight mounting, and tight zip ties.

Jon S
06-14-2008, 12:31 PM
OK, I just completed recapping my Monitor 10Bs... First off, the imaging appears to be better focussed. Secondly, where did the bass go? There is absolutely no bass after the recap. Is this normal until I break the caps in? I have played about 20 hours on them so far and there does not seem to be any improvement.

Celt
06-14-2008, 12:41 PM
Sounds like you may have the woofers or speaker system wired out of phase to one another.

Face
06-14-2008, 01:16 PM
Sounds like you may have the woofers or speaker system wired out of phase to one another.
I did the same thing the first time I worked on my Monitor 7's.

Jon S
06-15-2008, 02:45 PM
Sounds like you may have the woofers or speaker system wired out of phase to one another.

not possible... I did not remove the connections to the speakers from the crossover during the upgrade. The Polk's do not really have any woofers anyway. it uses a passive radiator.

also, weird anomaly... when I listen to James Taylor's "Gaia", 4:15 into the song there is a serious drum roll. the Polk's goes really down low on this track, rattling the room. on the contrary, listening to the soundtrack of "Titanic", track three, "Southampton" is loaded with a bass drum tempo that really belts out the bass, but on the Polk's, hardly anything comes out. Listening to the same tracks on a pair of Polk LSi15s, the bass is low on "Gaia" but kicks ass on "Southampton", opposite of the Polk 10s... Don't understand why.

YamahaFreak
06-15-2008, 03:03 PM
not possible... I did not remove the connections to the speakers from the crossover during the upgrade. The Polk's do not really have any woofers anyway. it uses a passive radiator.

also, weird anomaly... when I listen to James Taylor's "Gaia", 4:15 into the song there is a serious drum roll. the Polk's goes really down low on this track, rattling the room. on the contrary, listening to the soundtrack of "Titanic", track three, "Southampton" is loaded with a bass drum tempo that really belts out the bass, but on the Polk's, hardly anything comes out. Listening to the same tracks on a pair of Polk LSi15s, the bass is low on "Gaia" but kicks ass on "Southampton", opposite of the Polk 10s... Don't understand why.

Maybe you installed some of the caps backwards? I'm not sure if that would affect the sound, or if the caps are even polarized models, but worth a check. :thmbsp: Also, you gotta have a woofer to make a passive move. The main driver in the 10's are the woofers in the 4's. ;)

lorne
06-15-2008, 08:55 PM
Hi John S ... you have a serious problem and IMO it has nothing to do with so called 'break/burn-in'. If I were you, I'd make a drawing that shows everything you should have done. Then make a drawing that shows everything you did. Leave two days inbetween each task. Do not refer to the former while doing the latter. Somehow you have altered the circuit. Sometimes the brain does some curious things, and we keep seeing things the same way when we should be spotting the error. I have found this to be true in auto and bike mechanics as well.

Get your multi meter out and start tracing. I'd sure like to hear from you when you finally find out what has gone wrong. ... Lorne

glum
06-15-2008, 09:53 PM
Well I finished my recap Today the speakers sound great I can hear things coming fron my recever that I was never able TO Hear before,,,,,,,,,,,,,,,, ITs time for a new resever!!!!! this is no longer Acceptable!

ShaneC
06-15-2008, 10:08 PM
I did some recapping this weekend.

Knocked out a pair of Sansui SP-50's, a single Technics SB-G500, and a single AR-2ax. (Remaining Technics and AR are for later this week)....

I've gotta say it really opened up the sound. Basically did a direct replacement of the old NPE's w/ Solens for the AR and Technics (though I had to jumper a perf board to hold the new caps for the Technics).

The Sansui's were a recent thrift rescue - cheated on those and used some Radio Shack NPE's w/ .1uF Dayton's as bypass. Seems to work pretty well.

Jon S
06-16-2008, 01:45 AM
Maybe you installed some of the caps backwards? I'm not sure if that would affect the sound, or if the caps are even polarized models, but worth a check. :thmbsp: Also, you gotta have a woofer to make a passive move. The main driver in the 10's are the woofers in the 4's. ;)

the Jantzen crosscaps I bought were non-polarized...

Jon S
06-16-2008, 01:51 AM
Hi John S ... you have a serious problem and IMO it has nothing to do with so called 'break/burn-in'. If I were you, I'd make a drawing that shows everything you should have done. Then make a drawing that shows everything you did. Leave two days inbetween each task. Do not refer to the former while doing the latter. Somehow you have altered the circuit. Sometimes the brain does some curious things, and we keep seeing things the same way when we should be spotting the error. I have found this to be true in auto and bike mechanics as well.

Get your multi meter out and start tracing. I'd sure like to hear from you when you finally find out what has gone wrong. ... Lorne

it appears that break-in is what it needed. the bass is starting to come around, i got about 30 hours on the caps now. i came across a stereo review magazine (12/1980) which reviewed the Polk model 10s... it reported that the passive radiator response rolled down from 60Hz at 6dB/octave... that's why the bass seemed thin... output drops below 60Hz. that's why my dealer recommended a subwoofer with the Polks back in the 70s when I was considering them.

lorne
06-20-2008, 11:02 PM
Whatever happened, I'm glad it worked out ... Lorne

Pete B
07-03-2008, 07:56 AM
Capacitor discussion and myths:
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=1431

Stock Advent restoration, and capacitor comparison:
http://www.classicspeakerpages.net/IP.Board/index.php?showtopic=2790

Pete B.

tubed
07-06-2008, 12:44 AM
Do mylar/poly capacitors have a freshness date guaranteeing we arent buying a stale cap? Thanks for all the info and antedotes everybody.

spkrdtr
07-06-2008, 06:49 AM
No, caps don't have freshness dates. The caps you listed are VERY stable and will last many-many years.
Old NPE's are the only caps I'm aware of that had a tendency to deterioriate over time resulting in drifting properties (those black and red Callins found in many KLH speakers excepted). This was a very slow process which was imperceptable to speaker owners who's listening gradually adjusted itself along with the drifting tweeter performance. So nothing unusual was perceived by the owner.

colterphoto
07-06-2008, 07:12 AM
Beranek's Law

It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.

L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.



In other words, if you spend dollars on components and time on rebuilding them, psychologically they WILL sound better. The only true way to make certain that you have made improvement in a loudspeaker is a blind A/B test. How many who have fiddled with networks have taken the time to pause halfway through the experiment for such a test?

colterphoto
07-06-2008, 07:16 AM
No, caps don't have freshness dates. The caps you listed are VERY stable and will last many-many years.
Old NPE's are the only caps I'm aware of that had a tendency to deterioriate over time resulting in drifting properties (those black and red Callins found in many KLH speakers excepted). This was a very slow process which was imperceptable to speaker owners who's listening gradually adjusted itself along with the drifting tweeter performance. So nothing unusual was perceived by the owner.

Klipsch Heritage speakers from the 70's and older will have old Paper-in-Oil caps that can leak and change value.

That being said, I agree completely with the second portion of this writing. The deterioration process is usually very gradual and happens over years, while the listener's age and HF hearing comes into play as well. So it's possible that freshening the caps can overcome TWO obstacles.

BECtoo
07-06-2008, 09:12 AM
Klipsch Heritage speakers from the 70's and older will have old Paper-in-Oil caps that can leak and change value.

That being said, I agree completely with the second portion of this writing. The deterioration process is usually very gradual and happens over years, while the listener's age and HF hearing comes into play as well. So it's possible that freshening the caps can overcome TWO obstacles.

I don't think that by the 70s Klipsch was using any paper in oil caps. Perhaps they did in the 50s or 60s, but all I have taken apart from the 70s have been some sort of film and foil in oil. But, whatever they are made of, they are all measurably bad by now at least in ESR and many are leaking oil.

Bob Crites

tubed
07-06-2008, 03:11 PM
Does anybody know if mylar/poly capacitors were available for speaker building 20-30 years ago? In the competitive speaker industry it seems as though manufacturers would have used the superior caps or maybe cost did come into play... I am assuming from what I've read on this Sticky the difference between contested caps are not sound quality but mainly deterioration issues which leads to the possible sound changes. Thanks

Jon S
07-06-2008, 10:07 PM
dunno about that, but I can tell you one thing... I just upgraded my Polk Model 10Bs with new Sonicaps. I had just upgraded them a month ago with Jantzen caps and decided to what the scoop was with the Sonicaps. They were four times as expensive as the Jantzens (six caps were nearly $200) but the sound improvement was worth the added expense. It brought the Polks into a newer and higher level of sound. the highs opened up with better depth and focus. it was simply amazing...