Old Ferrofluid... Possibility of My Tweeters Overheating?

CAT5e

New Member
Last weekend I picked up a pair of Energy Model 22 Pro Monitors for $60. Only problem I discovered was a bad woofer which just turned out to be a simple cold solder joint. Fortunately both of the tweeters are working great, but I'm worried that they might not last too long.

After all, these speakers are from the early 80s, and I bet that the old ferrofluid in the tweeters dried up years ago. How can I increase the lifespan of these great speakers? Like, will running them for shorter periods and allowing time to cool help at all? I'm of course not going to blast the volume.
 
Ferrofluid

Well if the tweeter is working as you say, then then for now you (they are okay). I used to buy my Ferrofluid from a company called Ferrofluidics Corporation--they would be the ones to ask about the lifespan of their product( Dr. Bill Boutenberg was the fellow I used to talk to there)Just guessing on my part,I would suspect that the lifespan would depend in part on the viscosity of what was used in your tweeters.

I suppose one of the things you could consider doing is taking your tweeter apart and cleaning out the gap and putting fresh Ferrofluid in.When we were using Ferrofluid we were told that if the voice coil former was Nomex or paper that we would have to seal the former or else the former would absorb some of the fluid and change the response characteristics of the tweeter.

Having said all that, sometimes Ferrofluid was used not only to increase the power handling of a cheaper tweeter but also to tame a spike in its frequency response.

If the fluid was dried out I would think that you would hear some kind of voice coil rubbing --See what some others have to say and proceed from there
 
I've been using my Pro-22's up to a year ago with my 100 wpc amp clipping sometimes and had no problems with the tweeters. Idealy they should be serviced, since I have no wish to do it myself I continued to use them. I don't normally listen to them loud though (under 10 wpc). I noticed the HF did seem too bright, sometimes shrill which I atribute partly on the dried up fereofluid which dampens the tweeters responce as well as keeping it cool.

With properly serviced tweeters and x-overs these speakers are real gems with higher end Gear surpassing my 27 year newer Energy RC-30 Towers. I even called Energy Speakers before I bought my Reference Connoisseur RC-30 towers and the fellow there said I would need their very expensive Veritas Line to equal the Pro-22's in their original operating condition.
 
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Oliver thanks for the info. I don't hear any sounds to suggest that it's dried out, but I did find some document online from the manufacturer that said the fluid should only last about 12-14 years. These are long past that!

Charles, glad to hear yours are going strong. I'm driving mine with an Audiolab 8000a. I think it's 60 watts/ch which is comfortably within the handling range of these speakers. I read on old threads that Energy used to service the tweeters for $110 each, but nobody can contact the guy to do it anymore. He was apparently the only one with the stuff to properly do the rebuild.

Well anyway, at least I can use them without so much worry since you say yours are cranking away fine.
 
CAT5: Most of the time I listened to them at lower power levels (10 wpc) rather than the 100 w I suggested. I only did that a few times, perhaps when your freinds come over and your tempted to impress them, it might be best to refrain from cranking it to high just to be on the safe side. Some people have had trouble with them. I'm just saying you should enjoy them, that's why you bought them, and thats hard to do if your affraid of frying them.
 
Interesting thread. Never thought about replacing ferrofluid in old speakers. So I did a search to see if anyone did this sort of thing found this outfit http://reconingspeakers.com/ They do replace ferrofluid in speakers. I have a pair of Warfedale W-35's one has a torn mid range cone, the other the same but in it's tweeter. Any original replacement for these BIC drivers would be just a old. The cones are very fragile after 40 years. The vintage speaker bug has bit me. One of the things I have learned is make sure any speaker you get is not orphaned as are the W series Warfedales. My Polk Monitor 10B's a 20 plus year old set still has it's drivers, and replacement tweeters, which are much better then the originals available.

Thank you for bring this topic to my attention, very, very interesting. Here is the link for the do it's yourself ferrofluid page. http://reconingspeakers.com/products-page/ferrofluid-diaphragms/ferrofluid-retro-kit/
 
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Good buy on the 22's!... you now own a piece of Canadian speaker history and some of the finest ever made anywhere, as you'll find out. Be sure to drive them will quality electronics because they are sooo very revealing of upstream crap and that leads some to believe they sound like crap. Once good clean high current power is put to them, they sing like no other.

I've been looking into the issue and will be attempting ferrofluid replacement on some Hyperdomes (Energy 22 tweeters) soon. I'm getting a few test subjects and if they go well I may try it on my own working tweeters. I have a few theories on the fluid issue and why these tweeters have been deemed "fragile" but once I get some apart I will know more. If your tweeters sound good I wouldnt worry about them. Feed them good clean high current power and enjoy them. If you notice any unusual sounds from them then perhaps they may have issues.

The ferrofluid is used in many tweeters to increase power handling by increasing the cooling. I "think" this measure is used by manufacturers as a safe guard knowing darn well that some, or many people abuse speakers by overdriving their amps into clipping or using crap amps that cant supply good clean power. I know of people who remove the old fluid all together and run them that way.

The Hyperdomes are becoming more rare and as far as I know there are no replacement voice coils/domes available so once the vc has opened or been damaged, you're done. This brought on the thinking by some that they should be taken apart while operational to replace missing or dried up ferrofluid. I'm still on the fence about that.

Here's a bit of reading from another forum where there are lots of 22 fans, and many threads. These 2 are regarding ferrofluid, one of them being mine and my adventures finding the stuff in Canada. The other is a member who has recharged his own working Hyperdomes.
http://www.canuckaudiomart.com/forum/viewtopic.php?f=6&t=24936
http://www.canuckaudiomart.com/forum/viewtopic.php?f=6&t=25000
 
I've noticed some suggest that the Energy pro-22's need very good equipment to sound good. I haven't noticed that. My Pro-22's sound "Good" on my Onkyo 70 wpc AVR (it's not crap...I wouldn't buy crap! It is nothing special however for typical owners of the Pro-22's). My Energy RC-30 towers also sound good on that reciever, but with less bass extension. I would say with the AVR Both speakers sound better than good, but the Pro-22's don't have much of an advantage.

However when connected to my Bryston Amp with their DAC it's clear the Pro 22's are in a different league. The inner detail, imaging, and coherency is noticably better with the 22's. But its tweeter is a bit more shrill than on the RC-30's, Perhaps due to dried up ferrofluid in the tweeters, and out of spec cap's in the x-over.

I had a Friend over who owns a pair of Definitive Technology Mythos ST towers with a 300w amp in each and he commented the RC-30's with it's 2 x 5.5" woofers made as much bass as the big Mythos. They probably play louder than the Pro-22 actually, but their Just not as real sounding with the better gear.
 
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The only cap that might be out of spec in the 22's is a 47uf bi polar electrolytic. The others are mylar. The lytic is worth replacing but the replacing the others most likely wont net any benefits.
And the 47 lytic is in the woofer section of the circuit. It's a crossover design that is well matched to the speaker system, not much use messing with it.
 
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Currently I have mine hooked up to both my Audiolab 8000a and an AVR. The AVR is a Marantz SR4000 (no, not the vintage one, one from the early 2000s). I have a little switch units that I made myself each using a double-pull-double-throw switch, speaker terminals, and plexiglass folded into a box-like shape. Here's a picture:
ekgkjs.jpg



So this lets me use it on my high quality amp and my AVR. I haven't turned the volume loud or ran any test material on my Marantaz, so I really can't say how they've performed using the lower quality amp. Either way, I'll be sure to not to test their limits even to impress my friends. They definitely sound amazing on the Audiolab with it's clean power.
 
Well if the tweeter is working as you say, then then for now you (they are okay). I used to buy my Ferrofluid from a company called Ferrofluidics Corporation--...

PE sells ferrofluid, and it is Ferrofluidics brand. :thmbsp:

Just cleaned out and refilled my JBL 046 tweeters last month. They were easy, but then, they were made to be serviced easily.
 
Ferofluid and other things

Sort of on the topic off the topic --- Electrovoice used to do a trick with their woofer voice coils --this would increase power handling and also prevent the voice coil from slipping off the end of the former --they would coat the voice coil with this goop(red/brown in colour)this is the same stuff that the old tv service guys used to smear on the yokes (I just can't remember the name of it--getting to old and forgetful ) anyway works good and is cheap (woofers only) Corona something or other --this is going to drive me crazy
 
Last weekend I picked up a pair of Energy Model 22 Pro Monitors for $60. Only problem I discovered was a bad woofer which just turned out to be a simple cold solder joint. Fortunately both of the tweeters are working great, but I'm worried that they might not last too long.

After all, these speakers are from the early 80s, and I bet that the old ferrofluid in the tweeters dried up years ago. How can I increase the lifespan of these great speakers? Like, will running them for shorter periods and allowing time to cool help at all? I'm of course not going to blast the volume.
This is a link that should be stickied on it's own or with this post since ferrofluid is so widely used.

http://www.ferrotec.com/technology/ferrofluid/

Most important point made in the writeup is that ferrofluid does congeal, which is a topic I brought up a long time ago. You'll see that the writeup specifically states that heat does cause this sooner, which likely goes against what many posts have stated i.e. "leave the stuff alone". Given the number of drivers burned out, with ferrofluid, it becomes apparent that playing at high volumes alone isn't the sole issue. Note, while driver VC's likely don't get as hot as the maximum operating temperature of ferrofluid, that doesn't change the fact that heat does accelerate the congealing process.
 
Corona dope

Thinking of this, corona dope?
http://www.mgchemicals.com/products/4226.html

It's used to prevent high voltage arching. I cant see what purpose it'd serve on a voice coil, other than making it thicker and that's not a good thing.

Well I used to thin mine down a bit --- never had any problem with rubbing --- it significantly increased power handling and as I said earlier also stopped the voice coil from slipping off the end of the former --- and I took the engineer at Ev at his word (if its good enough for Ev its good enough for me)
 
Good info Copa!

My links from the post above refer to a post I made somewhere else on my adventures finding ferrofluid in Canada. I could get educational fluid easy enough but thats not for use in speakers. I've since managed to get some and in the process I hope I've given a Canadian distributor some incentive to stock some.

I'll be experimenting soon with a few Hyperdomes and ferrofluid, I'm hoping I can get at least one successfully working.
______________________________________

RW, sounds good to me too! Something to look into further.
 
Good info Copa!

My links from the post above refer to a post I made somewhere else on my adventures finding ferrofluid in Canada. I could get educational fluid easy enough but thats not for use in speakers. I've since managed to get some and in the process I hope I've given a Canadian distributor some incentive to stock some.

I'll be experimenting soon with a few Hyperdomes and ferrofluid, I'm hoping I can get at least one successfully working.
______________________________________

RW, sounds good to me too! Something to look into further.
Do let us know.
 
Update:

I've just taken apart 2 Energy Dual Hyperdome tweeters donated to me by a very generous member of CAM.

My observations are just that, I have no scientific facts, just opinions.

One tweeter has an open voice coil and is beyond repair. The other measures about 4 ohms. I will assume it would work but I didn’t put signal to it.
The open one when taking the vc out had wires popping out like a slinky. Obvious signs of severe overheating. The magnet gap is still almost full of ferrofluid.

The 2nd tweeter has some separation of the vc windings. About half the windings are loose but still intact. Another sign of overheating. The magnet gap is almost full of ferrofluid. It’s worth trying to rebuild.

Both have ferrofluid residue on the outside and inside of the outer dome and on the inside of the inner dome. This makes me think that some fluid was forced from the gap either by heat or over excursion of the diaphragm. Obviously finding fluid on the diaphragm some was missing from the gap contributing to the further overheating of the vc once the fluid was displaced. I believe the tweeter's demise came first from being over driven, loosing some of it's ferrofluid, getting too hot and the binding agent that holds the coils of fine wire in place around the plastic vc cylinder breaks down allowing the coils to separate. With further use the fine winding wires get forced down into the gap and due to constant grinding from the vc movement they eventually open.

So are these tweeters more fragile than some? I doubt it but I cant know that unless I know how they were used, or abused. A voice coil gets warm quite fast with use and heavy use over long periods of time can build up a large amount of heat. Of course clipping heats things up much faster and if being hit with high wattage midrange frequencies at the same time causing excessive excursions of the vc, that may be the cause of the now hot and thinner fluid being splashed up onto the domes where it begins to wick, taking more fluid and quickening the heat damage. Either the plastic vc cylinder becomes distorted from the heat and the coils break loose from their binding or the binding itself lets loose.

Once the process of the windings separating begins to happen it snowballs leading to the eventual breakage of one of the fine vc wires. The windings don’t appear to have serious signs of excess heat such as looking black or melted although there is some minor signs of high heat.

I dont believe the fluid "dries" up but rather it is displaced. So what's the answer to keeping these tweeters intact? Probably the same as most speakers. Feed it with good clean power, and don’t run them at high power for hours on end. Give them a cooling break now and then. Anyone who owns 22's and knows them well knows they are very selective of what drives them. If our ears object, the tweeters are objecting and telling us so. If the 22's dont sound amazing with what you're driving them with, feed them what they want and I believe they'll be happy and last as long as any other tweeter. I don’t believe they’re that selective and any high current well behaved amplifier should suffice. Just don’t expect them to be at their best when driven by a lightweight surround receiver for example.

If there's an oily looking film on the outside of the dome(s) you can check if it's ferrofluid by lightly rubbing a Qtip over it and if there's brownish residue, it's ferrofluid and that tweeter will not cool as well as it should and the vc windings may be on their way to separating or worse, already separated.

I'm going to try to reattach the loose coils to the cylinder although I don’t know what to use to do that with. Lacquer, Corona Dope? Any suggestions are always welcome.

It'll be cleaned up to get rid of the fluid all over the domes and windings, the gap will be filled with new fluid (when and if I get it) and put back together. Secured in place and adjusting the vc position while monitoring their output from a mic connected to a scope, fed by a signal generator at about 850 - 1000 hz.

It’s been suggested to coat the inside of the domes but that to me goes against the original design. The domes are not airtight which means they can breath thus dissipate some of the heat. By coating them they cannot breath and may accelerate their demise. I will be leaving the domes uncoated, true to their original state.

Sounds simple.....not. But I do want to try.
And of course any of this is theory on my part.
If anyone knows of where one can get new or intact diaphragms/voice coils for these tweeters I'd be interested in hearing about that.
 
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