Musings on improving vintage speakers - what do you think?

Since I've started renovating my AR-4x speakers, I've been reading around a bit about them, online. Ran across this, regarding the 3as:

http://murphyblaster.com/content.php?f=AR3a.html

Not the same model, but parallels can be drawn for most of these old speakers (other ARs, Advents, whatever...), and this has me thinking... these speakers, by all accounts, sound great. Out of respect for them as "audio history", I'm inclined to restore them to near-original state, first, but that "urge to improve" never entirely disappears. Several thoughts/questions result:

(1) He mentions the crossovers and the the severe cancellation in the mid-highs and the hump near the top of the woofers range. In a case like this, would "modern technology" give us a means to improve on the crossover and get a flatter response, or would this come at the expense of the sound? Are these speakers BETTER sounding for having these dips/humps, perhaps because they offset particular characteristics of the drivers, OR are they good IN SPITE OF these irregularities, and thus subject to improvement?

(2) There has been mention here recently of how good Advents sound after re-capping with recycled old oil filled capacitors (1000V). There was mention in the thread of some superior characteristics of oil-filled caps, too. Would this be a good/wise replacement choice in other/all speakers? I'm seriously considering getting them to try in my 2axs, which will be next up for a re-cap. If oil-filled caps are really that good in this application, why hasn't there been more mention of them in the past?

(3) He mentions no consideration having been given to driver placement. Assuming one kept box type (sealed, ported, etc...) and dislacement volume constant, would the sonic improvement from a more scientifically-determined driver placement be worth the effort of new box construction? I'm thinking of narrower front baffle for the tweeters, set back from the woofer enough so as to be time-aligned. Worth the hassle?

Another reason (besides restoring the ARs) that I'm considering these issues is that I found a home-made pair of speakers made with a TEAC midrange and crossover, mated with JVC SX-series woofer and tweeter. Someone apparently decided that a great 2-way would sound better if converted to a 3-way using a mediocre midrange. :headscrat The woofer and tweeter are seriously good drivers (tweets look very similar to those on Dynacos and Advents, with metal grills over them) from originally 2-way speakers. I know that is what they are because I look at them (SX-3 IIIs) and listen to them daily in my home office. [The woofers have an 8" cone mounted in 11" surrounds, 12" with grill, quite unmistakeable!] Since the homemade cases on the ones I found are cruddy (crudely built raw plywood), I could just pull the drivers and try to "improve" the sound of the original speakers, without having to sacrifice a vintage pair to make the experiment.

Just musing aloud here... any comments/suggestions from the more experienced DIY speaker guys here?

In a case like this, would "modern technology" give us a means to improve on the crossover and get a flatter response, or would this come at the expense of the sound? Are these speakers BETTER sounding for having these dips/humps, perhaps because they offset particular characteristics of the drivers, OR are they good IN SPITE OF these irregularities, and thus subject to improvement?

Click to expand...

I think if you put a LEAP-designed crossover in a speaker that was built way before that ever came along, you've changed its character. Whether that's good or bad, depends on you. Some people would say adding any EQ is heresy, some aren't that much of a purist.

Part of the allure of the vintage speakers I've heard has been the frequency response...which may not be as ruler-flat as the computer-designed crossovers but still manages to make some pretty darn good music. I think there's a time and a place for both kinds of speakers.

I think a lot depends on condition and rarity, and of course the quality of the original. I don't see any reason to zealously guard a ratty pair of AR4xs -- not only are they very plentiful, but they make no claim to be unimprovable, since they were clearly simply the best AR could do at that pricepoint and time. On the other hand, I wouldn't mess with something like a Paragon or a Quad ESL -- not only would you lower the value, these were statements by their designers and companies, and have some claim to being lesft unmolested.

Arkay said:

Not the same model, but parallels can be drawn for most of these old speakers (other ARs, Advents, whatever...), and this has me thinking... these speakers, by all accounts, sound great. Out of respect for them as "audio history", I'm inclined to restore them to near-original state, first, but that "urge to improve" never entirely disappears. Several thoughts/questions result:

Click to expand...

Ignore the "accounts." We just went through that in another thread. Devise means to ascertain what sounds good and what doesn't, yourself. Technology can be of considerable assistance in this.

Arkay said:

(1) He mentions the crossovers and the the severe cancellation in the mid-highs and the hump near the top of the woofers range. In a case like this, would "modern technology" give us a means to improve on the crossover and get a flatter response, or would this come at the expense of the sound? Are these speakers BETTER sounding for having these dips/humps, perhaps because they offset particular characteristics of the drivers, OR are they good IN SPITE OF these irregularities, and thus subject to improvement?

Click to expand...

They're not all that. The fact that they have an identifiable "sound" is ample evidence of inherent coloration. If you like the character of a 10 dB wideband notch smack in the center of the high frequencies, then by all means, let them be. Verify that before deciding. Measure. More data, less wank.

Arkay said:

(2) There has been mention here recently of how good Advents sound after re-capping with recycled old oil filled capacitors (1000V). There was mention in the thread of some superior characteristics of oil-filled caps, too. Would this be a good/wise replacement choice in other/all speakers? I'm seriously considering getting them to try in my 2axs, which will be next up for a re-cap. If oil-filled caps are really that good in this application, why hasn't there been more mention of them in the past?

Click to expand...

They aren't all that, either, but they're cheap. Try them. Set up so you can switch back and forth between them and other solutions. Make a meaningful empirical determination and move on.

Arkay said:

(3) He mentions no consideration having been given to driver placement. Assuming one kept box type (sealed, ported, etc...) and dislacement volume constant, would the sonic improvement from a more scientifically-determined driver placement be worth the effort of new box construction? I'm thinking of narrower front baffle for the tweeters, set back from the woofer enough so as to be time-aligned. Worth the hassle?

Click to expand...

What hassle? This is a hobby, and a damn enjoyable one. Get the books and figure it out. Do stuff that you find has potential for making actual and significant improvements.

Arkay said:

Another reason (besides restoring the ARs) that I'm considering these issues is that I found a home-made pair of speakers made with a TEAC midrange and crossover, mated with JVC SX-series woofer and tweeter. Someone apparently decided that a great 2-way would sound better if converted to a 3-way using a mediocre midrange. :headscrat The woofer and tweeter are seriously good drivers (tweets look very similar to those on Dynacos and Advents, with metal grills over them) from originally 2-way speakers. I know that is what they are because I look at them (SX-3 IIIs) and listen to them daily in my home office. [The woofers have an 8" cone mounted in 11" surrounds, 12" with grill, quite unmistakeable!] Since the homemade cases on the ones I found are cruddy (crudely built raw plywood), I could just pull the drivers and try to "improve" the sound of the original speakers, without having to sacrifice a vintage pair to make the experiment.

Click to expand...

You can't do it without measurement capability. I'm gonna quote Zaph, who seems to know something about this. It could be Danley, D'Appolito, or a whole bunch of others telling you the same:

Get a decent measurement package, start measuring some drivers, and then start listening to them, in different applications and without filters, alone and in systems with other drivers, just so you can hear exactly what you see. In time, understanding will come.

Click to expand...

Any other hobby, you'd have the requisite tools and learn how to use them. Do it. :yes:

It really depends on what level of detail and determination/inspiration you are willing to put into the project.

I've seen people take vintage speakers, and make really interesting revisions. Two that come to mind immediately, are Bob Crites and Al K., with regards to various vintage Klipsch models. Some may like the original voicing... but it has to be said, that both of those guys have made VALID variations on the theme... with more "modern" tonal balance. In addition, some designers have actually re-visited their OWN designs later, to good results- Richard Russell (of McIntosh) is an example of these, in his offering of improved mid/tweeter arrays for the old ML1 speakers.

As was said above, we DO know A LOT more about tuning and designing speakers, than the state of the art allowed in earlier decades. Now, there is a case for real genius being able to get around a lot of the "status quo technical difficulties" of an era... but, it IS a big advantage to KNOW MORE. Helps avoid a lot of time-consuming pitfalls, that might have sucked up great amounts of time, in older days.

OTOH- there's SOME vintage designs, that were so METICULOUSLY designed in their day, that changing ANYTHING will upset them, requiring IMMENSE WORK to get things back in order again. The prime example of this, IMHO, is the Dahlquist DQ10... it's ALREADY a GREAT speaker, as is, for all intents and purposes. Changing ANYTHING in that REALLY COMPLEX system, is a recipe for LOTS of SUNK TIME AND EFFORT, in order to get it to behave itself again. Some things were just simply optimized TO THE HIGHEST LEVEL for what's in them, already...

So, it's possible to improve SOME vintage designs... it's just a matter of WHAT it's done to, and HOW it's done...

In the case of the AR3 project above- it sounds like limitations in crossover design theory and measurement ability in the time of its construction, limited the ability to account for what SEEMS like a big CANCELLATION between the woofer and tweeter, near the crossover point. With modern design tools, it MIGHT be able to design a nice crossover network, that might more effectively side-step the phase problems of the original in the region of the big "suck-out" in the response...

Regards,
Gordon.

BTW: a really INTERESTING mod for an AR4, would be to substitute an EPI or Genesis inverted-dome tweeter, with appropriate cap (10uf, rather than the 20uf in the AR4 originally). After all, one of the reasons Winslow Burhoe left AR to form EPI, is that the AR management wouldn't let him develop that type of stuff, for the AR4...

Regards,
Gordon.

GordonW said:

BTW: a really INTERESTING mod for an AR4, would be to substitute an EPI or Genesis inverted-dome tweeter, with appropriate cap (10uf, rather than the 20uf in the AR4 originally). After all, one of the reasons Winslow Burhoe left AR to form EPI, is that the AR management wouldn't let him develop that type of stuff, for the AR4....

Click to expand...

If that means a higher crossover frequency, swap out the woofer with LE8T:

http://audioheritage.org/vbulletin/showpost.php?p=58297&postcount=1

So much for AR4x.

NEXT!!! :

[Needs a sub....]

Edit: What they are today, below:

With a 10uf on the EPI tweeter, it's about 1900 Hz. Will work fine with the AR4 woofer.

Regards,
Gordon.

I'm with GordonW, get some known good used tweets from friends, neigbors, the bay, whatever and try them in one enclosure against the original. For less than say $50, you will know if you can improve the situation easily. The EPI tweets are pretty wide range and pretty forgiving. They are slightly set back by design so they'll help with timing issues. See what happens? Doesn't work, sell the bits, tell us how it worked out and finish the restoration.

Lots of folks have told me that "voicing" a speaker is the human trial and error part. The paper design gets you close, then things get tricky because we are not spectrum annalyzers. We have holes in our hearing and sensitivities to some freqs over others. Speakers that play well to these nuances get good reviews and develope a following.

Have fun and teach us all what you find !!

GordonW said:

BTW: a really INTERESTING mod for an AR4, would be to substitute an EPI or Genesis inverted-dome tweeter, with appropriate cap (10uf, rather than the 20uf in the AR4 originally). After all, one of the reasons Winslow Burhoe left AR to form EPI, is that the AR management wouldn't let him develop that type of stuff, for the AR4...

Regards,
Gordon.

Click to expand...

The same can be aplied to the Original Large Advents.

Nat said:

I think a lot depends on condition and rarity, and of course the quality of the original. I don't see any reason to zealously guard a ratty pair of AR4xs -- not only are they very plentiful, but they make no claim to be unimprovable, since they were clearly simply the best AR could do at that pricepoint and time. On the other hand, I wouldn't mess with something like a Paragon or a Quad ESL -- not only would you lower the value, these were statements by their designers and companies, and have some claim to being left unmolested.

Click to expand...

They're all platforms and drivers to me. If I had HPM-100s, for example, all that'd be left would be the woofers, probably, based upon recent discussions in another thread here.

Don't think I'd take a SawZall to the Paragon, but I'm certainly not above driver swaps and crossover mods to render it listenable, at least.... :yes:

How about...

trying a set of Genesis inverted domes in a KLH 20? I just happen to have a pair sitting around...:scratch2:...Never a bad idea to grab a set or two of these when you can find them....:yes:

analog addict said:

trying a set of Genesis inverted domes in a KLH 20?

Click to expand...

Why not? The EPI domes worked VERY WELL in a KLH 33, here at the shop!

BTW: The EPI tweeters are almost direct BOLT IN fit to the recesses in the KLH 33 baffles! They fit right in the recess- all you have to do is drill new screw holes! I'd think they should fit the same in a KLH 20 or 17 (or 6) as well...

Regards,
Gordon.

Hmmmm....

GordonW said:

Why not? The EPI domes worked VERY WELL in a KLH 33, here at the shop!

BTW: The EPI tweeters are almost direct BOLT IN fit to the recesses in the KLH 33 baffles! They fit right in the recess- all you have to do is drill new screw holes! I'd think they should fit the same in a KLH 20 or 17 (or 6) as well...

Regards,
Gordon.

Click to expand...

Where did I put that drill and screwdriver??? I guess the only issue will be any impedence change. Well, the two tweeters measured within an ohm or two, so what the hell...Swap complete on one speaker, and initial A/B comparison not all that different. Will need additional listening time to better evaluate....:scratch2:

BTW, they aren't a straight drop in for these tweeters. The Genesis have a larger flange, so a couple of screws and a lot of rope caulk later, and we're in business...

GordonW said:

BTW: a really INTERESTING mod for an AR4, would be to substitute an EPI or Genesis inverted-dome tweeter, with appropriate cap (10uf, rather than the 20uf in the AR4 originally). After all, one of the reasons Winslow Burhoe left AR to form EPI, is that the AR management wouldn't let him develop that type of stuff, for the AR4...

Regards,
Gordon.

Click to expand...

Gordon,

I don't know whether to thank you or curse you. I have 2 pairs of project AR-4x's and a neighbor who had a pair of EPI 120's at yesterday's block sale. Looking out my window they're still in the driveway. Hmm.

It will be interesting to do a side by side test - when I get enough space cleared to actually work on all these projects.

Thanks - I guess.
Tom

The EPI tweeters are stll one of the finest dome tweeters around, as long as they are a relative sensitivity match, they will workon nearly anything.

Interesting thread. I have a apir of AR4x cabs/woofers that I ganked the tweets out of to fix a prettier pair. I can't remember from having them open. Does the woofer in that have a choke in series and a cap across it or does it roll off au naturel?
Agreed on the EPI/Genesis tweets. They made a ton of those and they sound really good to me. I consider that a significant upgrade over the older AR cone tweet.

Yep, the EPI tweeters can be marvelous (they are in all of the applications I've heard them in). Human Speakers has an updated version of them that is much more extended on the top end but is otherwise similar. I haven't tried them yet, but would like to hear them.

Anyone tried them yet?

I think that bracing and panel dampening can be helpful. On my big Infinities, I added an internal brace between te front and rear panels, just under the woofer. That seemed to tighten the bass a bit. I've since bought some vibration dampening mats to stick on the insides of the bass box and maybe the upper panels. Dynamat is one brand.

Adding spikes to the base of floorstanders is another tweak. I first tried hardwood stick-on knobs which helped a lot on my concrete floors of my garage listening room. I just got a set of big spikes I'll add at the next opportunity.

Another easy improvement is to re-wire inside. I ran 10 gage speaker wires only for it to go to 20 gage behind the terminals. We can do better!

A more drastic improvement can be had from an external, active crossover. One might have to split the drivers and add another set of terminals.

One can do a lot to an old set of speakers without having to monkey with an actual electrical redesign.

The EPI tweeter swap sounds interesting- but at that point, I'd just go to the EPI 100 and call it a day. I'd leave the AR4x, warts and all, as-is.

Now, even a cap replacement is a modification of some sorts, but if the caps are bad in the AR4x, then it's the lesser of two evils, as the caps may be way out of spec after 30 or so years.

My AR4x have been re-capped, and the sound is much improved- from "wooly" and "warm" and laid-back to much more potent on the top end- cleaner, clearer, more forward.

at most, for any of my speakers, I'd consider firstly some additional bracing, and if they were to be keepers, then also possibly some internal damping.

But that's just my opinion, and what I'd consider.