Air Motion Transformers (Heil's) and New Diaphragms

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Re: Bump for 30kHz

badman said:
Has anyone else actually measured the current drivers/ribbon (yellow mylar)? The 800-9k number seems very brutal :bigeyes: , making the driver almost useless, for those of us who can actually hear above 9k ;)

Do we know if the french magazine was measuring the mylar ones?
 

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Re: Re: Bump for 30kHz

Terry Demol said:

Wasn't sure if that would come out. Yellow diaphragms, from memory
one of the plots was 2 stacked vertically and the other just one.

This is the later style thicker (3mm) lamination Heil.

As you can see they certainly do go past 20k.

We also tried sonic comparison of the older (soft clear) diaphragms
versus the newer yellow ones and the new ones were cleaner
sounding, but they both had their own slight character.

I have them ruunning with Altec 414c 12" alnico MB driver and
it's one of the few drivers that work with Heil.

cheers

terry
 
In this same post I attached the measures done with the later version of the Great Heil with Yellow cartrige and as you can see the measures are very good.

Post #28
http://www.diyaudio.com/forums/showthread.php?postid=670521#post670521

I have had the 3 versions of the cartrige, the original "soft" from 1972, the clear version from 1994, and the last Yellow version.

There are no issues with the yellow version, they sound fine and go up to 20K no issues.

cheers.
 
Greetings Heil AMT fans. I've had my Concept CE-Monitors (Pacific Stereo house brand made by ESS) since 1976. I'm still on the original diaphragms which sound like new even though they have suffered much use and occasional abuse. Since this thread began long ago many changes have taken place. Replacement diaphragms for original AMTs are no longer available from Orange County Speaker or elsewhere. The assets of ESS have been bought up by a German company now producing speaker systems costing $12,000 or more. Drivers can be purchased from a German Web based company for $690 Euros each (not a typo) plus shipping. Diaphragms do not appear to be available from this company. Oskar Heil's family founded a company in Switzerland also making an "improved" version of the AMT with systems costing $7,000 and up.

Those of us with vintage AMTs are out of luck if we need replacement diaphragms.

With that in mind I have begun the process of building my own diaphragms. I have purchased mylar in two thicknesses I'm planning on trying. I realize ESS started using teflon near the end of their time in Sacramento, but I can't figure out why, where they bought the teflon, or how they got their adhesives to stick. Teflon is a challenge to work with.

Quote from Nelson Pass in this thread from long ago:
As I recall the original Heil diaphragms were polyethylene,
not Mylar or Teflon. These later materials were tougher,
but never sounded as good.

The original, best sounding material was made from the
packaging material for airline peanuts, and may still be
in use in the food packaging industry. <end quote>

I will try the material used in cereal boxes, which we all know is indestructible and will last forever. So typical of our throw-away society. It is in the range of the correct thickness and should work fine. In any case it will be cheaper than the mylar I've purchased as long as I eat my Cheerios.

I should have my first prototype done within a week. I'll post results here. If successful, I plan to make small production runs of these diaphragms which I will make available to Orange County Speaker. If there is enough interest, I will follow that with new AMTs complete.

Meanwhile, if anyone reading this has ever blown a diaphragm, please post what the circumstances were, how old, and if possible, what material it was made from. I've read elsewhere how fragile they are, but in my experience they can take a serious beating without harm. 30 years later mine still crank like new.
 
I haven't checked to see if this company actually has them in stock, but they do show the proper part number of 689-1107 for the Great Heils.
http://www.speakerrepair.com/ocsdiaphragms.html

I bought my AMT1's brand new in the early 70's, and they are still my favorites today. I've never had to touch the Heils and they sound as good today as back then, but I did replace both of the woofers due to age disintegration of the surrounds (I bought new ones directly from ESS about 10 years ago when they were still in business in California).

I jump in here because I have recently picked up another pair of the Heil units that came off of a set of Rock Monitors. I'm planning on using them as the starting point for a set of homebuilt speakers, and I'm thinking of cloning the "Kithara" speakers shown here:
http://www.unitedhomeproducts.com/id101.htm

I'll be back with some questions for those of you who have built your own using the Heils.
 
Note the "NLA" by the part number. No Longer Available.

They've asked me to supply them should I get into production.

Cloning the Kithara will be a fine project should you get it right.

Keep us posted.

That Syrinx looks like a beautiful thing too and more reasonably priced. Interesting angled woofer in these speakers.

I have a pair of AMTs in that flat configuration. They're not as efficient as the "Great Heils" but the sound quality is the same. I have no idea how old these AMTs are but I've not seen anything from ESS in that shape, but then, ESS made a lot of different speakers. I plan to use them in a ceiling mounted OB system with the AMT mounted on/below the bottom of the baffle.
 
I can't believe I missed the "NLA". I guess I was thinking of something else... like how I get to play online while at work sometimes. Life is good. :)

I've decided on the Kithara design for sure, and I've begun the AutoCad drawing and am filling in the blanks as I go along.

However as you suggest, I have a lot of research to do if I am going to do it right.
Since the Heil is going to be mounted at the top, it doesn't really need any design considerations having to do with the speaker box itself, but I'm having to give some serious thought to the bottom section and how it will perform with the 10" driver.

Of course, the manufacturer gives no clue about the interior design they use, probably for competitive reasons, but I doubt that it's just an open bottomed box (they do state that the bottom is open ported).
I'm toying with the idea of working out a transmittion line design for several reasons, and I'm open to ideas about that.
For me, deciding on the interior design of the bottom box is the most difficult part of the project.
 
Best of luck on that part. There are many good TL boxes out there and ESS even made a few. You should know these AMTs are very particular about the crossover network you employ. It will be a sweet speaker to bi-amp using an active adjustable crossover. If you choose to go passive you might want to buy a used ESS crossover on ebay as a starting point.
 
Hi Braggi, greetings from the underside of the world (Australia). I have just picked up some old ESS units (SP12 something). They had a 12" bass unit with a foam covered Aux bass radiator mounted at the rear of the box. I'm familar with the "Greater Heil" from mag' reviews and early promos many years ago. I guess what I have bought are the "Lesser Heils" They look similar to the units in the 'Syrinx' or 'Aulos' models that are on the "unitehomeproducts" website. If so, they look like they run from about 1k Hz and are 4 Ohms acording to the combined system spec'. From your experience can you confirm that please? and can you give me any further info' on them. Thanks Jonathan
 
G'day Jonathan,

The new Syrinx and Aulos are new products from a new manufacturer and we shouldn't assume they compare to any of the old ESS models exactly, although they might be upgrades from the old ESS lines.

All of the "Great Heil" drivers and systems I'm aware of have a nominal impedance of 6 ohms. I do have a pair of those flat ones as I mentioned earlier which I'll have to investigate with my meter to give a DCR. For now assume the system is 6 ohms.

Do you know if the Heil unit in yours is open behind the diaphragm? The AMT-2 (If I have that right) is the model with the magnet assembly directly behind the diaphragm and only fires forward. Then there's the flat one which ESS used in bookshelf speakers with the sealed tube behind. Although I've heard the AMT-2s and they do have that sweet AMT sound, the dispersion is hampered severely by the design. The flat ones (need to find the name of these) can be removed from the boxes, have the tube removed, and remounted on top to give the full 360 degree dispersion the Heils are famous for. I recommend it highly.

BTW, regardless of many folks' comments to the contrary, the old ESS woofers are worthy of refoaming so don't toss them out if the surround is looking bad. Mine have the 12" pulp cone woofers and came with 14" flat passive radiators. When my passives died I had to replace them with 15" cone passives since they never made replacements for the 14s. I think the bass response is now deeper and fuller so it was a fine thing to do. If you like chest thumping low bass, you'll need to add a sub but I think that's the case with most speakers from the '70 and '80s so no surprise there.

Good luck bringing them back to spec.
 
Oops, forgot to mention the crossover: AFASIK, all the greater Heils were crossed over by ESS around 1,000 hz. I've heard the AMT-2s were crossed at 2,000, but I don't know that for certain.

I'd be careful running them much lower which could smoke the diaphragms. I understand when overloaded the magic smoke that makes them work is released and that it smells real nasty.

Take care, mate.
 
Hi Braggi, Thanks for the prompt reply. I've done a bit of searching since the last post. You're right, mine are clearly not the same as the "Syrinx" et al. Mine have 6 slots in the face plate and I think their's have 8. The ESS model number is PS 12-C. The bass and passive unit are both 12". The active unit looks a bit "CTS ish" and is in good condition. The Heil unit has a fairly substantial mild steel face plate that is over an 1/8" thick and measures roughly 21/2" by 4" There is a plastic cavity behind the unit that would hold about two cigarette packets or a bit more. There was also a larger plastic cover over the front of the high frequecy units that can only have "muddied" the sound while trying to improve the aesthetics. I haven't done a wiring diagram yet but there are 3 coils and 3 capacitors which look pretty fragile. It may be a third order c-over but its complicated by a pot to adjust level and a small item that may be a thermal cut out. Will explore more tomorrow.
I've run a frequency sweep through them and they are clean to 12.5kHz with nothing after that which I think means I can still hear up to 12.5k! which was a pleasant surprise.
I'm probably going to run them at a higher frequency in a three-way rather than a lower cross over. As the complete pair of boxes cost me 56 little Aussie dollars (about $46 US) I felt I've got a reasonably cheap bit of history.

On a less thechnical note I notice that your begun your reply with "G'day" and concluded with "mate". Does this mean you are familar with Australia or just watched too much of "The Crocodile Hunter"? Thanks again Jonathan
 
Naw, never saw "The Crocodile Hunter." Used to watch the Paul Hogan Show when I was a kid. I haven't watched TV since 1975. Here in the US we all want to be Aussie, at least to try it out. Paul Hogan makes it look like a lot of fun. Would love to come over and spend a few weeks there.

Check these out: http://www.springsguide.com/classified/DisplayAd.asp?id=450

They look like nice little three ways, but I'm not sure that's better than leaving the Heils covering a wider frequency range. You'll have to let us know how your project turns out.

12.5 K? Yeah, my HF hearing drops off fast above 12 K as well. Damn. I drove a very noisy old bulldozer for a few months when I was 17 with no ear protection. Of course, it's a male trait anyway that our hearing will be less sensitive in HF as we age, but I don't think the industrial age has done men a lot of good in that department. Means we need to have young ladies come by and listen to our systems to make sure the tweeters are working correctly. :)

Good luck on your build.
 
Hi,
I wanted to come back to Jonathan and Braggi's mail about the impedance of the Great Heil.
I measured the resistance of the Great Heil cartrige (I assume that it is purely resistive, not capacitive or inductive) and I find 3.5 to 3.9 Ohms (there is variance, I measured 8 great Heil cartriges).
The AMT 1 A, B, C , D, E and Monitor woofers are around 6 Ohms impedance (from litterature)

Cheers,

cdfr
 
Lets get someone to make the replacement part!

Hey guys:

I have been thinking about trying to make the "689-1107" diaphragms also. But I must admit I've noted some things about them that discourage my confidence in a successful outcome:

First of all, the conducting traces on all but the very early diaphragms are not single aluminum strips, but rather two side by side "serpantine" tracings that appear to be etched, or more likely printed on to the mylar/polypropelene/whatever membrane surface.

The back of the tracings appears to be coated with a black material (teflon?), or perhaps the entire tracing is some kind of conductive material that is black, though I don't know what that would be.

The circuit that these tracings form is more complicated than a simple "square wave" patern. It appears to double back on itself at least once over the entire membrane surface.

I have recently met a DIY member, here in my neck of the woods, who claims to have this circuit recreated as a CAD file. Nevertheless, I personally do not have the means to print this circuit onto a membrane...How would one go about that?

Then of corse, there is the membrane material issue, that has been addressed here, but not really resolved. But should we be able to work out all the other issues, that would leave one free to experiment with all sorts of materials....I can tell you that I was once told by an ESS tech that the all-Teflon-coated diaphragms were a disaster.

There is the problem of the mesh grid that is adhered to the top edge of the pleats on both the front and back of the mounted diaphragm. What is it? Where can we get it? With what adhesive does one attach it? (You can't see any excess adhesive around the mesh at all, and it's quite solidly attached to the membrane.)

I do know that ESS claimed this 'gri'd was necessary to keep the diaphragm operating within spec for any period of time.

Finally there is the matter of the correct surface tension to keep while mounting the diaphragm into the frame. Does anyone have any idea of what this should be, or how to measure it?

I have been told that by design, Heils do not require as strict of tolerances as other types of audio drivers (as the electric signal will force the "push-pull" pleats into alignment), but they do require some reasonable tolerances, none of which I know in the least.

Not to discourage anyone, but all this does present quite a challenge for even the most talented, educated and well equiped DIYer, any of which I certainly am not. Still, circumstances may force me to attempt it anyway. If anyone knows the answer to any of the above questions please post replies....

Meantime, something has occured to me: The void left by ESS is quite a considerable market for a third party part maker, or another speaker manufacterer. After all, the Heil AMT patent has expired, there is obviously a large demand for this part, and it shouldn't be that difficult for a technical facility to re-create it...so why not?!

All we need to do as a group, is figure out who would be the best candidates to approch for making the part. Then we all write to them 'en masse' until one of them caves!

Perhaps Parts Express, ScanSpeak/Tymphany, or Madisound would be interested. These companies are well aware of Heil AMTs. I'm sure you all can think of quite a few others.

What do you folks say? If anybody thinks this is an idea worth giving a try (or not), post a reply. In following the rules of this forum, should we decide to go ahead with this, we'll start a new thread.....

After all...we need a reliable source to get AMT digaphragms from! Do you really want to spend all your speaker-building time and effort trying to re-create this single, complicated part?!
 
Braggi said:
Matt!!!

Shhhhhhh!!!!

Nobody's looking, right?

I think there will be a new source of AMT diaphragms soon.

OK?

Patience, my friend.


ESS/HEIL AIR 689-1109 RIBBON DIAPHRAGM-AMT-5

1-5/8"x2-15/16"

Air Motion Transformer

(Temporarily discontinued) $89.00
NLA





ESS/HEIL AIR 689-1107 RIBBON DIAPHRAGM-AMT-1A/1D

1-9/16"x5-9/16"

Air Motion Transformer

(Temporarily discontinued) $89.00
NLA

from here-

http://simplyspeakers.com/12diaphragms.htm

11596
 
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