| ESS AMT-1 Air motion transformers ?! - Click HERE for Original Thread |
| promitheus |
Has anybody heard or even made some speakers using the AMT-1 Tweeters. Or better midrange tweeters ?
I really need some info on them.
Thanks |
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| kelticwizard |
Apparently, the company is back in business.
From:
http://www.audiocircuit.com/9041-es...041CMAL-QUE.htm
Question
Rick Garret posted the following question concerning ESS:
Can you provide any information on Heil ESS louspeakers? I have a pair and would like to find any information I can on them. Thanks for your assistance. Rick Garrett
Answer
J.M. Willigens posted the following answer on the Heil ESS:
These loudspeakers used specific transducers, called "air motion transformers", which have nothing to do with ESLs. More with a ribbon transducer, in fact a folded ribbon was subject to a variable electromagnetic field, thus folding or unfolding and "quenching" air particles, which were forced to move in a vibration. The Heil ESS was an hybrid, as the air motion transformer was only good from medium upwards. The bass was an ED loudspeaker, quite often downward-firing. I am not sure, but think that Oskar Heil passed away, but some german company has reintroduced an ESS recently.
Answer
Barry Waldron posted the following answer on the Heil ESS:
In addition to J. M. Willigens' response, here is some background on the company. The company was founded in the late 1960s or early '70s in Sacramento, California. "ESS" stood for "E)lectro(S)tatic S)ound" and its first products were indeed hybrid electrostatic loudspeakers. There were various bookshelf and small floor standing models that utilized a Transmission Line woofer and single electrostatic tweeter.
One or more models used the B-139 6" x 9" oval woofer*. The tweeter was a single ended oval driver complimenting the shape of the woofer. As I recall, the speakers actually sounded quite good; moreover, the use of a Transmission Line was unique and an ideal match for the tweeter. This combination was not used again, commercially, until the introduction of the InnerSound EROS in 1997. (Audiophile hobbyists began using long Transmission Lines to compliment electrostats in 1977 after the publication of Roger Sanders' first homebuilt speaker project in "The Audio Amateur" magazine.)
As remarkable as these speakers were they did have two major limitations. The first was that the line length was necessarily short that prevented really low bass reproduction. (Subwoofers and bass commodes were not popular for several more years.) Second, the electrostat was limited for use as a tweeter by its single-ended design. (Modern ESLs are push-pull and incorporate a front and rear stator working together, along with a "constant charge" on the diaphragm, to reduce distortion and widen the driver's useful range. A single-ended speaker uses just a backplate ) over which rests a metalized Mylar diaphragm. Because the electrostatic force can only influence and control one side of the diaphragm and its resulting travel, distortion increases as it moves further away from the backplate. It is for this reason that the design is limited to tweeters and is no longer popular. (I find it interesting that some popular ribbon and planar magnetic speakers continue to be manufactured using the s/e design approach.)
My educated guess (not having interviewed company personnel) is that the company recognized these performance restrictions and was looking for ways to improve their products. Enter Dr. Oscar Heil and his amazing A)ir M)otion T)ransformer. This is a driver that uses a pleated diaphragm mounted vertically within a very strong magnetic field and motor structure. The action of the diaphragm is to "wiggle" the pleats and "squeeze" (to use the company's definition) out the sound at high velocity.
The company manufactured a variety of speaker beginning with the popular AMT-1. The AMT drivers were made in different sizes. To the best of my knowledge, ESS was the only licensee of the good doctor's creative genius. As Mr. Willigens noted in his comments, there is also a German licensee perhaps having obtained it through ESS.
During the heyday of the AirMotion Transformer, the most remarkable, yet outrageous development was the Transar (please correct me if I have the model name incorrect). This was a Rube Goldberg device that used a multiple of tiny soft plastic cones mounted vertically, one above the other. Several stacks were attached to the front of a baffle, each driven by carbon fiber rods that connected the many cones together. A voicecoil motor assembly was mounted at the bottom of the assembly. This speaker was a full-range AMT. It never achieved any degree of popularity. If you can find one, it should be preserved as a museum piece.
ESS moved its manufacturing facility several times and went dormant for a few years. The company is back in business and sells its products through company stores on the West Coast and some dealers on the Eastern Seaboard. It is my understanding that they have a sizeable export business.
Copyright: <../../9105-copyright.htm> The ESL Circuit, member of TAC (The Audio Circuit) (home) <../9041IMAI.htm>
Last modified: Thursday, December 13, 2001
*The KEF B-139 is a woofer frequently used for transmission line systems. It is no longer made. It's sensitivity was 84 dB/1M/1W. I do not know if the fact that the B-139 was matched with the AMT unit means that the AMT had a similar low sensitivity. High frequency units are often, not always, more senstitive than the woofers with which they are matched. Kelticwizard. |
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| kelticwizard |
According to the website, the AMT can crossover as low as 800 Hz.
http://www.essspeakers.com/
Also, some more information here:
http://www.snippets.org/ldsg/sect-2.php3#TWEETERS
CTRL+F "heil"
I would just add that I auditioned some speakers using a Heil back in the seventies. To be honest, I was not at an age where subtlety was what I was looking for, and I mostly noticed that the speaker did not put out much basswise. It was not terribly expensive, though.
I do remember reading that the critics of the time thought the Heil unit was very good. |
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| promitheus |
Thanks a lot , that a lot of interesting info.
I am checking already the links you sent.
I know a project that uses 2 focal woofers 8V4411
with one AMT-1 and the whole thing has 95 dB response. |
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| Mark A. Gulbrandsen |
I worked in a Hi-Fi repair shop that was part of a large Chicago area Hi-Fi shop chain, Midwest Hi-Fi. This was at the height of ESS's early years. Not only did they build some great speakers but they built preamps and power amplifiers, as well as powered sub woofers.
If I remember correctly the Air motion Transformer had distortion almost as low as an electrostat did. The transformer was super efficient due to its huge magnet structure. All of the components as well as charging of the magnets was done in-house at ESS at the time. I recently tossed an old AMT-1 transformer out as the pleats were melted together....a common problem of these. I was also not aware that ESS was still around. Had I known I'd have more likely kept the thing. It made a great doorstop! I'm also pretty sure that Dr. Oscak Heil was the inventor of the Magnetron tube back in the ole days for radar.
We also did a number of experiments with the transformer and we found that a small rear baffle to delay the rear wave a bit made for a much better midrange. I also remember seeing the prototype full range "contraption" at the Consumer Electronics show in Chicago in the mid 70's. ESS was really a prolific company. I'm glad to see they're back.
Mark Gulbrandsen
Salt Lake City |
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| promitheus |
| From what I have found, you can change the ribbon for 120$ or something if you manage to destroy it. I seriously think about using these drivers but the price is very high. It has 510 Euro in Europe i guess thats a little less than 500$. Its quite a lot of money for drivers. But the good part is you need no midrange, it goes down to 1000-1200Hz at more than 96 dB. Very good for a 2 way speaker. the only thing you need is a mid-woofer arrangement that is also as good. |
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| promitheus |
| This is the latest hi end project using the AMT-1 with 2 focal drivers at 95 dB. |
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| Mark A. Gulbrandsen |
I don't think the 500.00 per driver is too bad. When you consider you'd have to either go with a ribbon or electrostat and either of these would cost even more to get comparable performance. One has to remember that the AMT is almost as good as an electrostat or ribbon transducer in the first place and capable of handling gobs of power. Melted diaphrams were common back in the 70's with these but back then really high quality power amplifiers didn't exist. I think Mark Levinson was just appearing at the time.
I now design and install sound systems for move theatres and I am going to be trying out an interesting new system from Stage Acompany which is a Dutch fim. They use ribbon drivers in their designs. The cabinets are only 9" deep, about 4 feet square, and with two 12" woofers and the ribbon unit capable of handling 1kw peaks without fatigue. They claim 130db spl max at that spec. Almost all of the Hollywood film mixdown studios have now gone to these speakers. They are also competitivey priced with JBL and E-V which are the other two popular brands of theatre loudspeakers. The SA ribbon unit is priced at about 700.00 or so.
Mark Gulbrandsen
Salt Lake City, UT |
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| promitheus |
Thatīs cool info on this subject.
So you think itīs a good buy ?
I really need to find them somewhere and hear them.
Greetings
Ilias Kamouzis
Germany |
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| Al.M |
Hi, I have been using these pulled out from an old 1982 ESS speaker. They work fine, see my project I am still playing with:
http://communities.ninemsn.com.au/b.../_whatsnew.msnw
The Heils are very good, perhaps better than all dome tweeters, better than Scanspeak 9900 I used. Because they have such a large radiating area the treble is extremely lush, detailed and full, like listening to several dome tweeters at once. They are very easy to work with & no peaks etc (audible).
However, I compared them with a Raven R1 recently and sadly the R1 is better, more modern sounding, extended & transparent, hard to believe really.
The Heil is still very good, some people have thought of using it as a cheap Raven R3. For midrange it is really only best above 2000hz or more. I have tried it in 3 way & 2 way & prefer the 5000hz xo point.
My email is abure021@hotmail.com if you have other questions. |
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| promitheus |
The raven is also cheaper from what I found.
Is the R1 good for a two way system ? |
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| cyclotronguy |
The original Heil Air Motion Transformer was really quite spectacular. I was lucky enough to have a pair in the mid 70's and at the same time a pristine pair of KLH-9 electrostatics. The two made an interesting contrast: The AMT was more dynamic, but the KLH had a slight edge on transparency and sweetness. Given the price difference between the two; the AMT was even more impressive.
To the best of my knowledge ESS has never dissapeared.... they've just been a bit obscure.
Oscar Heil is indeed deceased but before his death sold his older design to Eton, and started a new speaker called the Oskar Aulos.
Just as by-lines the great Nelson Pass and his wife were part of the original ESS and I believe largely responsible for voicing some of their better product. Dr. Heil was a prolific designer, responsible for the FET and some dramatic changes in geological exploration hardware.
Cyclotronguy |
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| promitheus |
So what do you guys think. Is the AMT-1 a good driver or do you have some other one to suggest.
I really need some help. |
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| Mark A. Gulbrandsen |
Ahhhhh, The good ole days.
I wonder if Nelson was the designer of the ESS electronics? They had a couple of power amps, a preamp, and powered subwoofer. I can remember repairing the 200 WPC amps quite frequently back in "74". The bias adjust on it was a bit temperamental at best. At 12:00 it was properly biased but at 12:01 it blew the outputs and went up in smoke. When properly set up it was the best sounding amp in ts class. Quasi output of course with minimal U shaped heatsink(fins).
Mark Gulbrandsen |
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| promitheus |
Thanks alot Mark.
There are a lot of good auktions going on in the US but I leave in Germany. Havenīt spotted any drivers here in our ebay yet. |
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| FBJ |
| If you don't mind taking info from a new guy. But there is an ad for the ESS AMT speakers at www.bsaudio.nl or go to the Directory ( bottom of DiyAudio page ) under Reference click on Links and then the first link, Audio Links -The Biggest (?) list of Audio Links?. It will take you to www.AudioLinks.nl. And there is an ad window for PIEGA of Switzerland. There is pictures of completed speaker with the tweeter you are interested in. |
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| promitheus |
Thanks FBJ.
I will check that out. |
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| Al.M |
Look at the Raven R2 as well. I think it is about US$300, again cheaper than the Heil.
You really should get Heil out of your head, they are good but there are modern tweeters such as the Ravens that are better. The R2 has 2 times the radiating area as the R1 and should be more dynamic and better.
All Ravens can be used to crossover at around 2000Hz but higher is probably better. I will be exchanging my Heils for Ravens soon.
Trust me! :) |
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| promitheus |
The Raven are more expensive then Heil here in Germany. The US toll department charges a lot of extra to oder from the US. The Raven cost here around 550 $.
Itīs too bad because I kinda liked them.
:-( |
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| Al.M |
You should to see if there is a Europe supplier, there must be. Have a look on the internet.
Good luck |
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| promitheus |
| Thats the price they sell it here. It costs allmost the same to buy it from US. |
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| kelticwizard |
Promitheus:
Just checked in to say that Parts Express, which frequently sells discount, is now selling the Raven tweeters. The R1, R2, and R3 are about $200, $300, and $1,600 respectively.
I have not the slightest idea of the costs involved in shipping to Germany. I just thought that I would inform you of your options.
http://www.partsexpress.com/webpage...r=287&cat_id=49 |
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| Nelson Pass |
Just for the record, I did not design ESS electronics.
Initially these were Peter Werback's (later of Linear
Power) and after that they were Bob Byrd (later of
AB Systems).
I just did speakers... :) |
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| FBJ |
That's right now I remember from the Harmon Kardon Citation 12 mod in TAA 2/81. Mr.Pass mentioned in that article he worked at ESS. But he didn't design electronics. Could Mr.Pass originally start out as a speaker designer first?
:confused: |
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| audioaficionado |
| An alternative to Ravens is ESg tweeters. They are not only more sensitive but are the only metal ribbons that are shielded and can be used next to a CRT. I plan on using one in a 100dB/W DIY center channel speaker. According to the importer they are comparable to Ravens, perhaps even better. |
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| planet10 |
| quote: | Originally posted by promitheus
Has anybody heard or even made some speakers using the AMT-1 Tweeters. Or better midrange tweeters ?
I really need some info on them.
Thanks |
Here is a cross-forum thread on the subject.
I heard (and took the pictures) of the AMT-1 conversion that Chris B did. The tweeters are nice.
dave |
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| prs |
i talked to essspeakers.com and found the price of amt-1d to be 180.00 ea. including the ribbon.
im thinking of building a surround system with these things.
what i need to know is what mid spkr would work best and what type fo x-over would be needed.
thanx all
pat ;) |
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| planet10 |
| quote: | Originally posted by prs
i talked to essspeake rs.com and found the price of amt-1d to be 180.00 ea. including the ribbon. |
Very reasonable
| quote: |
im thinking of building a surround system with these things.
what i need to know is what mid spkr would work best and what type fo x-over would be needed. |
After Chris finished with his AMT project, he figured he would have been further ahead if he had used the Audax PR17 (paper version).
As to other possibilities, you should be probably looking at the 6" pro mids that are available -- i know eSpeakers has a nice PHL. An alternative might be a pair of the fairly high effeciency Focals.
dave |
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| planet10 |
| quote: | Originally posted by prs
what type fo x-over would be needed. |
I'll ask Chris for a map of the XO he used for his AMT project. That would give you some good ideas and at least the HP on the AMT would be useful.
And do have a read thru the Decware thread i posted earlier, lots of good info there.
dave |
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| ezmeralda11 |
| A little of topic, but I noticed elac (www.elac.com ?) has a heil air motion transformer too called their JET tweeters. Much smaller and circular--don't knowhow deep it goes or if they sell it standalone or what. It seems like the Germans as a whole are doing alot of "high-tech" stuff, even more so than the american scene. I don't know everything out there so it may be a biased view: but they've got the bending wave transducers, the only speaker company I know if with a plasma tweeter in production, heil air motion transformers, etc. None of which necessarily means higher-fidelity, but... |
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| prs |
thanx for the info.
ive been thinking of building an amt-1 surround system for some time and now i guess im about ready to do it. I'll use my hsu sub with it.
should be cheap enough to build , and sound pretty good.
pat |
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| promitheus |
After a long time I am back to these posts here.
I got a pair of AMTīs to make some speakers.
I was supposed to use them in a 2 way system with 2 focal 8V4411 woofers per box. I canīt find these anymore, so I was thinking about a new design idea.
If you have any ideas for a 2 way system with amts please share here.
I am looking for a bassbox that goes up to 1800Hz at 95 dB. |
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| phase_accurate |
Hi Promitheus
In the current issue of the German magazine "Hobby HiFi" you will find a project using the AMT.
It is using 3 Seas 17 cm drivers (OEM versions) in a step-response and frequency-response optimized 2.5 way setup.
Regards
Charles |
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| phase_accurate |
Hi Promitheus
I forgot to mentio that this speaker's effieciency is only 90dB and it's impedance is only 2.7.Ohms.
Regards
Charles |
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| promitheus |
| Yeah I have this magazine. It is a very interesting design but too complicated for me. I want something with two woofers if possible in a 2 way speaker. I have seen some good woofers from seas or peerless but I canīt really say that something is fitting. |
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| promitheus |
Hallo again,
I decided after some time to continue with one driver from SEAS an 8inch with 93 dB ef. thats goes up to 2000 Hz so I can make a high impedance speaker of 8 ohm. It has a Fs of 29 so I think it can go low enough in a transmission line.
I can continue from there at 1800 Hz with the Air motion transformer, but I have to cut it since it has high efficiency. |
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| capslock |
promitheus,
which AMTs did you buy?
In the current issue of Klang+Ton, there is a project for an active speaker with the Eton ER4 AMT. There were passive versions also this year (Duetta and Duetta top).
Eric |
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| promitheus |
| I have a pair of AMT-1 from ESS, the newer version. |
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| Thatch_Ear |
I have been working on a 2 way TL design with the Heil AMT. I am going with a very wide range woofer from Eminence that goes up to 10K. I am planning on letting the woofer run free and using only a 6db high pass on the AMT.
I had a question about the phasing and was told to align the AMTs diaphragm over the woofers voice coil.
David |
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| planet10 |
| quote: | Originally posted by Thatch_Ear
I have been working on a 2 way TL design with the Heil AMT. I am going with a very wide range woofer from Eminence that goes up to 10K. |
Wouln't that be more appropriately called a Full Range?
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I am planning on letting the woofer run free and using only a 6db high pass on the AMT.
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Pretty much what jac (from over on the Full Range Forum is doing right now. He has Coral Betas on the bottom.
dave |
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| Thatch_Ear |
Kinda,not really. The Eminence beta rolls of at 10K but goes down to around 40Hz. Most full range drivers start higher and go at least up to 15K or so. This will be more along the lines of the Hammer but using a TL, and an AMT intead of a Super Tweeter.
Frazier did something like this in a kind of back loaded mini Onkin encloser using an 8" driver I believe Utah made for him back in 62. Not too deep they were the 'Bookshelf" of the day. I bought a pair off a guy and played them like crazy till the cones started falling apart. The woofer ran free and there was a 6db high pass on the tweeter. Very efficient as will be the Beta 12LT and the AMT. Probably a SPL of 97 to 98db/w/m. I want something very tube friendly and want to build it for the Texas Shootout which means I have to get started soon.
David |
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| promitheus |
I was looking around for 8 inch woofers but I canīt find anything linear and with 93-95 dB.
The best I found is the Focal at 90.8 dB all the way linear to 3 Khz.
In a transmission line I think it will be ok. |
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| planet10 |
| quote: | Originally posted by Thatch_Ear
[B]Kinda,not really. The Eminence beta rolls of at 10K but goes down to around 40Hz. Most full range drivers start higher and go at least up to 15K or so. |
A matter of semantics then -- I know what you are trying to say, but 8 octaves in my book is a FR -- just missing an octave at either end, pretty balanced FR IMO. My FR are stretching to reach 60-80 Hz and a lot of tweaking & fiddling has the Ts coming in at about 10k, and it is definitly classified as a FR. I figure if it covers 7 octaves and is fairly balanced beetween top & bottom it is a FR.
dave |
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| capslock |
There is a similar design in the Aug./Sept. issue of the German magazine Hobby-Hifi.
It uses an AMT-1 with some triangular structure behind it to deal with the backwards emmission of this dipole. Frequency response, decay time and disto plots of the AMT-1 are given (I guess without the case). The latter two are very good while frequency response has a strong directionality, showing severe high range loss at 30° horizontally or 10° vertically. Measurements of the whole speaker do not look much different.
Three special OEM Excel 17 cm woofers are used in separate bass reflex enclosures, two of which are allowed to operate up to 5 kHz and then rolled of at 6db/oct. The AMT is rolled of at 1.5 kHz, again with a first order filter. This broad overlap is supposed to result in a very "time-correct" behavior.
The Excel woofers, which have varnished magnesium membranes, have exceptionally low decay times and disto and are very flat out to 4 kHz when measured separately. There is a resonance at 4.5 kHz which is flattened within the XO.
In the completed system, there are some narrow dips up to 5 dB in frequency response, which must be due to the fact that three speakers are operative simultaneously. But they claim that this does not matter at all in a typical living room environment where room reflections have a larger effect. On the contrary, they claim that this speaker sounded extremely musical no matter where one was sitting.
Eric |
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| Thatch_Ear |
Dave,
I know that it is considered to be a full range by many, but compared to a Lowther it's higher roll off at 10K just makes it hard for me to toss into the same catagory. But there ya go, a matter of semantics.
Kind of like like a single axis triax or a duplex. Full range, one basket but 2 motors. So is a 604 a single full range driver? Yes, but not really.
One of the reasons I like terms like mid range instead of dynamics or would call the Beta 12 LT a wide range instead of a full range.
It certainly can be used as a full range if you don't want to hear the complete range of frequencies in a recording. But since to be able to listen to the complete range you have to add a high frequency driver can it really be a full range? Conondrum.
So anyway I am soon starting construction on a 2 way using Heil AMTs and an Eminence 12" Conondrum in a TL.
Capslock, can you give me a bit more info on the triagular structure behind the AMT? Being able to build behind the AMT could be a great help with fitting the TL pipe into a cabinet.
David |
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| capslock |
David,
maybe I can scan the drawing next week. It is basically a triangular piece the internal volume of which is dead. I believe you could also use the internal space.
Eric |
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| capslock |
Anybody have any experience with the Eton and Elac AMTs?
The Eton ER4 dipole AMT is about half the price of the AMT-1 by ESS, and it does not seem to be the AMT-2 (which is a monopole) with just another baffle. Distortion and pulse behavior seem to be on par with the AMT-1 from what I could gather from articles in speaker building magazines. I wonder how they achieve a homogeneous magnetic field with the hole thing being less than 10 mm deep and hence much smaller than the magnets of the AMT-1.
As for the Elac JET, I have seen some nice review of finished speakers in hifi magazines, but I don't think it is available for diy.
Eric |
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| fdegrove |
hello Promitheus,
On the ESS speakers: if memory serves me correctly I think ESS had a AMT tweeter and a midrange tweeter unit.
I heard their speakers on several occasions both in the mid-eighties and later on.I must say I was impressed with their clarity and razor sharp speed in the most sensitive midband.
They had (as a complete system) two problems to my ears :
1/ they were rather directive ,seating was important ( this may be partly due to x-over design )
2/the woofer never seemed to be able to cope with the sheer transient attack over midrange-tweeter unit.
Other than than that they were amazing speakers which were very easy to drive even to ear shattering levels.
Even now I would go for them without much further thought.
Converting dollars to Euro : 120 USD cannot possibly turn into 500+Euro even allowing for shipping and import taxes.Sorry but something just does not compute correctly here.
Why not buy them directly from the US ?
3/The only European company for DIY speakers I know of using ribbons is German based Visaton although it's just a tweeter I can think of putting it to good use in a D'Appolito configuration for example.
Hope this was useful. |
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| Sjef |
I have compared the AMT-1 to the Raven R2 tweeter, and also to the DECCA/Kelley DK30 and the Jordanow HRA531.
The Raven sounds more sophisticated than the AMT, but it can alos sound rather thin. That's meanly due to the fact that the Raven has got a rising output from 5 towards 30 kHz (like many ribbons do) The AMT on the other hand has got a bump between 3 and 10 kHz and has got an almost 4 dB lower output at 20kHz. (the DK30 on the other hand is completely flat within 0.75 dB!! from 3kHz to 30 kHz, can't measure any higher but it still goes on after that) You really should have to compensate for this, it helps a lot for the top-end defenition of the tweeter. After compensation it sounds almost as good as the Raven but with more "balls". Compensate the Raven for its output rize and it will be sounding "fatter"as well. However I still would not recommend the Raven to be used any lower as 3, better even 4kHz, not that it isn't capable of going any lower but it will become to thin again. Also forget about 6dB/oct filtering with them, they really don't like that, they can easily move out of their linear filed in this way. Steeper filter get a lot more detail out of them. Wouldn't use the AMT either with 6dB at 1,5 kHz or something. Never have understood the choice of ESS to combine them with a 10" woofer.
Problem with both drivers (as with almost any ribbon) is to find a suitable midrange wich can come up with the speed of these units. That's the reason I still have a love/hate relationship with ribbons. It about a hundred times easier to combine a midspeaker with a relativly slower dome tweeter, but I still haven't heard (have had Focal, Scan Speak, dynaudio, seas, Thiel, and several others) one yet that can come up with the detail and micro information of a good ribbon. Choosing for a ribbon means that that's the startpoint of your design, choose the other drivers to match them, otherwise you're risking a great dissapointment. |
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| promitheus |
Well itīs a long time since I started this thread. I have finished my speakers by now.
I used 2 8 inch HDS205 woofers from peerless.
They sound great.
I am still fixing the crossover because I had a few problems.
The woofers had a 3-4 dB Bumb between 800-3000 Hz so I had to use a parallel L-C-R circuit to flatten the bump. I got a lot more bass. The mids where so loud before that I could here much bass.
At the moment I am concerned with the tweeters. I use them above 2200 Hz with a second order filter. The crossover I found for them has a cap that somehow corrects the output of the Tweeter but I am not sure if it is right.
Does anybody have info on the ESS tweeter. I mean Output to Frequency chart. |
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| Vigier |
Did you mean something like this?
Grtz, Joris
P.S. I just sent you an email about all the measurements... |
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| promitheus |
Hi,
thanks a lot.
I think itīs the same as mine. Do you think this is accurate?
Would you correct this or use it as is.
I have read somewhere that the tweeter doesnīt need any compensation because the load remains flat. |
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| Vigier |
Hi Promitheus,
You know where I got this graph from :)
There are always some differences between the measurements of Klang&Ton and HobbyHifi, but i think they give a very good indication of what the units do. (usually the T/S parameters differ, but the measurement-graphs are pretty much the same).
To calculate the filter you should measure the output of the unit(s) yourself (to get the best out of the units).
I use those graphs for selection of units, but measure it myself when I have it.
Grtz, Joris |
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| planet10 |
Here is the measured response from the 1st set we used:
dave |
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| promitheus |
Hi,
thanks for the graphs.
What did you guys do with the crossover?
Did you use the tweeter as is or did you do any correcting?
I use the tweeter with a second order filter at 2200 Hz. |
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| Dsims5354 |
| This is the 1st time I've ever posted to Anything(!), so please forgive any protocol errors. In 1973 I purchased a set of Heil AMT 1's after much research and listening. The comments so far are pretty accurate, but there are some serious discrepancies. Yes, the bass wasn't much. But the AMT's were outstanding! They are NOT ribbon or ribbon-like tweeters. In actuality, the convoluted diaphram acted more like 2 groups of bellows acting in seies, but in opposite directions. Hence, a dipole. Mine crossed over at 700hz. And they were seamless and pretty linear all the way past 20khz. Remember, every crossover point is an adventure in phase distortion. Also, the efficiency was 93db/w/meter in the INSTALLED driver........through a fat resister to better the woofer's 91db/w/m! In 1974 I purchased a second 10" woofer and desined a proper ducted port enclosure for them. 'Talk about night and day! Using a 3rd order crossover I acheived 28 - 22khz +- 4db. With small amps of the day clipping their little butts off you could over heat and melt the pleated diaphram. Just use a bigger/better amp. My next speaker project will feature multiple Heils or Ravens. I'm looking for a source for the old ElectroVoice 30W. No, it isn't a 30" woofer: It's only 28.25"! |
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| EchoWars |
| quote: | Originally posted by planet10
Here is the measured response from the 1st set we used:
dave |
Is that impedence graph accurate???
I have an old pair of the Great Heil's (or so ESS tells me they call them), and had no idea that the impedence was so low. A bit over 3 ohms is, well, suprising... |
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| hifi |
Its a ribbon (more or less) so one can expect a low and almost perfectly flat impedance. ;o) But how do you like them?
/ Micke - who plans to buy a set of Amt:s |
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| planet10 |
| quote: | Originally posted by EchoWars
Is that impedence graph accurate??? |
Made with LMS... i have no doubt it is accurate
dave |
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| EchoWars |
| quote: | Originally posted by hifi
Its a ribbon (more or less) so one can expect a low and almost perfectly flat impedance. ;o) But how do you like them?
/ Micke - who plans to buy a set of Amt:s |
I wouldn't trade them for anything... :D
planet10...you woudn't happen to remember which version of the diaphram the Heil you tested used? I realize that the curve may vary somewhat from one version to the next, but are all the ESS Heil's 'about' the same low impedence (3 ohms and change)? |
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| planet10 |
| quote: | Originally posted by EchoWars
planet10...you woudn't happen to remember which version of the diaphram the Heil you tested used? I realize that the curve may vary somewhat from one version to the next, but are all the ESS Heil's 'about' the same low impedence (3 ohms and change)? |
The only ref i have is the pictures in my Planet_10 HiFi Audio Vendors Bazaar thread...
dave |
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| Mark A. Gulbrandsen |
I used to work for a large Hi-Fi dealer in the Chicago burbs back in the early 70's that was an ESS dealer. We did alot of expereimntation with them including placing a small baffle behind the AMT to slightly delay the rear wave. This made a noticable improvement in the lower mids. Has anyone else here tried this?
Mark |
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| EchoWars |
Not with mine...I'm running 2-way with the Heils crossed over at about 2500Hz.
I love the Heils, but the Dynaudio's I have for the bottom end sound much better doing midrange duty from 2500Hz down. I know the Heils can go lower, but I've never cared for the sound of them in the hardcore mids (800 to 1800Hz). IMHO, they don't 'come alive' till 2K or so. |
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| Urloony |
| quote: | Originally posted by EchoWars
Not with mine...I'm running 2-way with the Heils crossed over at about 2500Hz. |
Are you using heil 10" drivers or do you have something smaller in order to crossover that high? |
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| EchoWars |
| Homebuilt cabinets, with two Dynaudio 20W75's in each. The stock cabs used 12" Utah woofers that were horrid (these began life as stage monitors). ;) |
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| Steve M |
This is an old thread, so it's a bit of a long shot! But Mark if you are still around could you please describe what size, type and placement of small baffle you used to get the Heil AMT to sound better in the mids ??
Having just acquired a decent s/h pair of 1977 vintage ESS AMT-1A's I am surprised at how good they are overall (after all these years the speaker is not at all dated sounding and the bass is gutsy to say the least), and this is in the context of someone who's used to Accuton+Ravens/Seas Excel magnesiums/ESLs and Fostexes!.
With respect to the slight lack of body in the AMT midrange, I have experimented with trying to get it to sound more natural/warmer and have found that Mark's earlier suggestion of placing a small baffle behind the AMT treble unit does indeed seem to work. All I have done is place a 4" x 8" x 2" paving brick about six inches behind the AMT driver, and it has the effect of giving more body to the upper mids without sacrificing the airiness of the AMT driver. I suppose this sends some of the backwave towards the front thereby increasing the strength of the midrange.
I also tried closing off the rear end of the AMT unit with a piece of MDF and dacron stuffed into the rear cavity as suggested elsewhere, but this seems to have a negative effect on transparency so I don't favour it.
Anyone else tried similar tricks and Mark if you're still around please comment ...
Regards,
Steve M. |
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| Truckee_Tango |
I haven't posted in ages, but this thread inspired me. I have a pair of AMT-1 air motion transformers which I acquired after having built DIY versions based on an old article from Audio Amateur. The home builts were OK, but the real thing is really nice.
I had the pleasure of visiting with Oskar Heil several times before he passed on. He had some wonderful stories, including how he invented the first transistors, and then due mostly to world war II lost credit to Bell Labs. When I visited him back I think in the early 90's or late 80's, he was working on a new improved version of the air motion transformer. The results were so much better than the AMT-1's, I wish they had been produced for us to enjoy. I'll have to see if I have any notes from those meetings. He also had a very interesting passive radiator cabinet design for a woofer to complement the air transformer.
Anyway, thanks all for the fascinating thread. I'll have to resurrect my AMT-1s and see how they compare to the Beveridge III's I am now using for my main system. |
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| splspeakers |
Do anyone have an idea on the best way to cross the AMT tweeter.
I have an old schematic that indicates 18dB/oct for the tweeter.
Also in the schematics are included brilliance an mid controls (ą6 dB)
Thanks |
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| JohnL |
What are you crossing it to?
I cross mine at about 1250, with a 48db/oct filter to a pair of 8s and the sound is great. YMMV |
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| promitheus |
I cross my ESS at 2250 Hz with a 12dB/oct.
I use them with 2 HDS205 Peerless woofers. So I get around 95dB |
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| planet10 |
| quote: | Originally posted by JohnL
What are you crossing it to? |
3k 1st order to a pair of Fostex 9"
dave |
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| essjohn |
| Hello, just picked up a pair of ESS AMT Monitors from a friend. I don't know if I can talk my wife into allowing them in the house! About 4 feet tall and frankly, pretty ugly burgundy tweed fabric and tired Oak veneer. My question is this...should I keep them or sell them? They sound excellent and other than the obvious aged cabinets are in very good original condition. I know the Heil tweeters go for about $300 a pair on eBay but think it would be a shame to tear up the boxes if they are desirable to someone as is. I am a fan of vintage US made HIFI and don't want to disturb them, but maybe the only real value is in the HEIL tweeters. Anyways, hope I am not being too much of a pain to post here, thanks for any input you may have... |
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| splspeakers |
| quote: | Originally posted by essjohn
Hello, just picked up a pair of ESS AMT Monitors from a friend. I don't know if I can talk my wife into allowing them in the house! About 4 feet tall and frankly, pretty ugly burgundy tweed fabric and tired Oak veneer. My question is this...should I keep them or sell them? They sound excellent and other than the obvious aged cabinets are in very good original condition. I know the Heil tweeters go for about $300 a pair on eBay but think it would be a shame to tear up the boxes if they are desirable to someone as is. I am a fan of vintage US made HIFI and don't want to disturb them, but maybe the only real value is in the HEIL tweeters. Anyways, hope I am not being too much of a pain to post here, thanks for any input you may have... |
Hello, I have a pai of bookshelf ones (only one woofer with passive radiator in the back). IMHO the woofer is definitely cheap if compared with the Heil tweeter.
I'm trying to rebuild the speaker keeping the tweeter and throwing away the ugly woofer.
Remember, a big box usually sounds better than a small one. You only have to face the SAF (Spouse Acceptance Factor). |
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| Jed |
| quote: | Originally posted by JohnL
What are you crossing it to?
I cross mine at about 1250, with a 48db/oct filter to a pair of 8s and the sound is great. YMMV |
Hi JohnL,
I'm trying to contact you regarding your speakers with ESS tweeters. I'm considering buying a pair of AMT1s from ESS and would like to possibly mate them to W22EX for midrange and RS225s for bass. I'm also very interested in your design. I've pmed you at htguide.com too- but it appears you haven't seen my message yet. Would like to know very much what you think about the AMT1 and how they integrate with the RS225s. I'm astounded by the clarity of the Heil Motion and right now I'm not sure if anything compares- even ER4! I can be reached at Jed(underscore)Kunz(at)bcsd.org. Thanks and hope to hear from you soon.
Jed |
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| JohnL |
Hello Jed,
Did you receive my messages? I've emailed you twice from 2 different accounts.
John |
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| Jed |
| quote: | Originally posted by JohnL
Hello Jed,
Did you receive my messages? I've emailed you twice from 2 different accounts.
John |
No, I think you may have to send the attachments to me through a PM (here)- unless the files are too big for that feature too. I just sent you an email explaining the situation I'm in. I think PM should work. Thanks and looking forward to seeing your designs.
Regards,
Jed |
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| BrettP |
I came across this forum while wondering what to do with a pair of these units: I pulled them out of a pair I'd bought new, loved and listened to for years, the bass driver cones eventually got blown out...(still have those if anyone wanted them too ;) , and life changes never let me get back to using the parts for anything...
So now I'm aware these things actually have some intrinsic value to audiophiles out there, is anyone on this forum still looking for a pair? Would $200. US and you pick up the shipping be out of line?
cheers,
Brett |
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| Puggie |
| Hi Brett could you email me at william_backhouse(at)hotmail(dot)com. I may be interested depending on postage (ie how heavy are they). |
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| Marik |
Once, for one of my customers I built an open baffle triamp system with AMC-1 on top, Audax PR170MO as a mid, and Titanic subs (also open baffle).
It had a very good integration between top and mid, with IIRC, crossover points at 225Hz and 1500Hz.
Although AMC-1 can go as low as 800Hz, you need a high order crossover to avoid low freq. overloading. With continiously variable 4th order electronic crossover I found 1200-1500Hz is a lower limit, when they start feeling "happy". |
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| Jed |
I've got a brand new pair of AMT1's I'll sell if anyone is interested. email me at Jed(underscore)Kunz(at)yahoo(dot)com.
Jed |
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| mrjam |
01-12-2006
| quote: | | I'm considering buying a pair of AMT1s from ESS |
21-03-2006
| quote: | | I've got a brand new pair of AMT1's I'll sell if anyone is interested. email me at Jed(underscore)Kunz(at)yahoo(dot)com. |
Someone in Italy received broken items from ESS.
Question:
Why are you selling the precious Heils? ;) |
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| Hector Ruiz |
| I have owned a pair of the AMT-1s since 1971 and still in use today. The high frequency response and accuracy is dead accurate. However, being the original version with the ported 10" woofer they are anemic in the lowest bass octaves. The published crossover frequency is 800Hz using a 12dB/octave passive crossover. The AMT Tweeter is so efficient that the is a 6ohm power resistor in series with the tweeters diaphram to pad down the delivered voltage. Since the voice coil is not wound, but instead folded, the unit is resistive, not inductive. That present a constant impedence to achieve high definition. Years ago I bought a set of "PolySwitch" resettable devices from Radio Shack and wired them in series with the AMT tweeters. Since then I have not had to replace them. Good thing since ESS was out of business until recently. These PolySwitch devices act like wire until an over-current condition occurs and then its resistance climbs (positive temperature co-efficient) to limit damaging current to the diaphram. As stated earlier, I used these since 1971 and haven't repalced diaphrams in over twenty years. My audio system consists of a Crown Straight-Line 2 Preamp and a DC-300A power amp (no light weight in terms os available power.). I would like to custom build a custom enclosure with one or two woofers for the low end and the HEIL's covering the highs. I have a Crown D-150A and a custom crossover for Bi-amplification of the respective drivers. Any suggestions on enclosures incorporating two woofers? All designs viewed so far so formulation for a single woofer. |
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| JohnL |
| quote: | Originally posted by Hector Ruiz
Any suggestions on enclosures incorporating two woofers? All designs viewed so far so formulation for a single woofer. |
I use an AMT with a pair of RS225s, makes a nice combo. |
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| castlesteve |
Hey Brett are those tweeters still available?
Steve. |
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| BrettP |
Good thing I happened to check the forum :)
Yes, they are and I've posted some photos so if you want to see them shoot me an email at b(dot)pawson(at)shaw.ca
and I'll send you the ftp link
cheers,
bp |
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| BrettP |
Let's try that again
really sorry
bpawsonatshawdotca |
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| Black Stuart |
Hi all,
I bought a pair of the 'Grand heils' from a friend who was introduced to the AMTs' a long time ago. He also bought from the States a pair of the very cheap looking 12" woofers that ESS used to use. Having heard them I know they are a pretty good match for the Heils.
I see many are using quite high x/over points. ESS used to x at 600Hz but changed to 800-900Hz.
Surely it's better to keep the x/overs out of the 'intelligence band' or as low as possible.
The idea of using a rear baffle with the Heils, would appear to be sound.
I don't like the idea of 3-ways and I have been searching for a year to find a suitable 15" woofer.
The last thing I want to do is throw away the Heils 95/6 dB sensitivity.
I don't think big heavy pro woofers are what is required and to that end have been thinking about Pioneer A38GU40-52F - 15". They are 8 Ohms but if a 900Hz x/over is used they should be operating closer to 4 Ohms. This Pioneer may be cheap (about $46) but it's paper, 100W/200W max, which is more than enough and well made.
One thing I see nobody has mentioned - active x/overs. For a 2-way only one is required. No more phase problems and no more energy wasted as in passive x/overs. Control belongs with the amps (bi-amping) which is the way it should be.
Interestingly it appears that the only reason chipboard was dropped for MDF around 1980 was one of economics. It, chipboard makes for far better speaker cabinet material. So this is the material I shall use for the woofer cabinets.
Also has anyone thought about seperating the Heils from the woofer, by making a frame just for the Heils. With active x/over/s situated on your equipment racks, you are then free to move the two elements (with 2-ways) for best acoustic response.
I will use a Berhinger active x/over to start with and will get some knowledgeable friends to design a valve version if things pan out right - which they should.
I would appreciate any input on any paper, 15" / 4/8 Ohm/ 96dB + which I realise are becoming harder to find as time goes on.
Black Stuart |
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| Sjef |
15"/96 db sound like a pro woofer to me. I think it will be a pretty hard job to find a suitable 15"woofer wich has a nice clean extension up to about 2kHz wich is what you will need when crossing at say 800-900 Hz. The only one's wich could do the job so far wich I have heard where some quite expensive TAD/Pioneer 15"woofers.
On the other hand it will be much easier to find a suitable 10 or 12" driver wich will be up to the task. Take a look at the range of PHL drivers. These drivers are also used by the very best PA compagnies as lowmid ranges. They've got some very good sounding 12"drivers with very good bottom extension, but as always (law of physics) the sensitivity drops a few db in exchange for this extension. In the end you will get aprox 92 dB sensitivity in an enclosure (wich is a whole lot more than the average 86db when typical "hifi" drivers are used)
I have read a lot about people using Eminence drivers with good results (like Bastanis and PI speakers) wich are cheaper but I don't have any experience with them. You might check on the PI speakers website and forum. |
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| JohnL |
| Here's an AMT crossed to a Lambda TD15, so it can be done. The Lambda he is using is a high efficiency model, he states the speaker is 97db. I haven't heard the thing, but he is using a 6 db/octave xover, I would definately want something steeper than that. |
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| Jed |
| quote: | Originally posted by Jed
I've got a brand new pair of AMT1's I'll sell if anyone is interested. email me at Jed(underscore)Kunz(at)yahoo(dot)com.
Jed |
I've still got these for sale if anyone wants to save $100. My email is above. Thanks!
Jed |
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| Black Stuart |
Dag, Sjef
do you have any website for me to look at these TAD/Pioneer woofers.
I sent an e-mail to Pioneer/Europe a couple of months ago, which incidentally is based in the Netherlands but got no response.
Hi JohnL, yes it can be done. In fact the only reasons that 15" woofers have not featured in many speaker designs are two-fold. One is the dreaded WAF (wife acceptance factor), which is of course their bulk and secondly the average size of living rooms outside of N. America.
Quite simply the style fascists have since the 80's demanded that speakers should have a small footprint, with multiple drivers - they just don't cut the mustard, compared to a 12" or 15" woofer and of course they don't have the efficiency either.
My reasons for wanting efficient speakers is that I will use less 'juice'with smaller output valve amps as I intend to build a house powered by alternative energy sources - PV ai'nt cheap.
Keep the info coming please. |
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| dshortt9 |
| I am using the Heil's with bipolar Klipsch 10" drivers salvaged from RF-7's. Series crossover around 1.8k. No padding resistor for the Heil, around 97 db sensitivity. |
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| Black Stuart |
Hi dshortt9,
they look great - one in the eye for the small footprint brigade.
Is that a port on the side or a passive radiator?
I was going to bid on a pair of 12" Klips here in Europe but they went for a pretty penny.
Are you using a passive or active x/over? Anyway I'd like to hear them.
Have you considered removing the Heils from any possible woofer cabinet vibration, or is there any vibration coming from your cabs.? |
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| dshortt9 |
There are 2 4" ports, one on each side. One 10" woof on front and one on the rear. I am using a passive series crossover, just one cap and inductor. This contributes to the excellent performance. Higher order parallel crossovers can work but are much harder to design and IMHO can arguably degrade performance. Maybe I am just going through a phase of minimalism. I like to keep it simple as possible. The drivers seem to match well since the woofs were meant to be used with a horn they are fast enough to keep up with the ribbon. The series crossover is easy since it is very flexible - regardless of the values used they will mesh the drivers well. I calculated the original values and tweaked them by ear. No boom or overhang, very articulate. can seperate 2 basses playing with no problem.
The fronts are 1" plywood and have no vibration to speak of, especially on the edge. The Heil's weigh 12 pounds so are not easily shaken anyway. They go down to an honest 32 hz and will startle you with transients like the 1812 Overature has. I literally jump at times. Always available for an audition. |
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| Black Stuart |
Hi dshortt9,
you can never go wrong keeping it simple. Using the Klipsch woofers is exactly right - as you say they keep up with the Heils.
I'd love to hear your speakers but Andalucia to Wisconsin is some trip.
Active x/overs - take a look at Rod Elliot's, Elliots Sound Products site & TNT-Audio for the articles on active x/overs. Until I read Rod's take on it, I just did'nt realise how much of an amp's power is dissipated in heating up the components in a passive x/over.
I've bought a Berhinger to start with but I can see a valve active x/over in the pipeline. |
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| Black Stuart |
Hi all
I've got two questions. 1st, - can anyone input on the following Pioneer woofers;
A30GU40-51D 12" poly 96dB/23-1,500Hz - 6 Ohms
A38GU40-52D 15" poly 96dB/24-2,500Hz 6 Ohms
A38GU40-52F 15" paper 96dB/20-3,000Hz 8 Ohms
My preference will always be for paper coned woofers and I've been told that mostly woofers will be working around 4 Ohms even if they are rated at 8 Ohms.
As the woofers have to work with the AMT's which are a steady 3.6 Ohms, I am steered towards the Pioneer polys about which I know nothing. I have read on another forum that the paper coned Pioneers are sonically excellant and a 'steal' @$50 a piece.
I have no intention of reigning in the Heils and would like to think that I could use the 15" Pioneer. The other solution is to parallel (2) of the 12" polys or (2) of the paper 15" or is this overkill.
Most important though is info on the poly woofers.
2nd, can anyone give me an address on the European mainland, where I can buy pioneer woofers. I may have an address for the UK but would prefer it if I can buy in Spain - either of these will save me a fortune in postage if I have to buy from the States. |
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| badman |
At first I was going to discourage you from the use of these drivers: but they're pretty nice seeming. However: you'll be hard pressed to get even the best 15" to keep up with the heils. You're talking about a 99% reduction in moving mass at the driver transition, so the 15" might not be able to reproduce the transient response you want for them to blend well. My own design for the heils (which hasn't been built yet) uses a 6.5" to go between the 15" and heil.
Whatever you do, good luck! |
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| Black Stuart |
Hi Badman,
I'm a complete novice at building speakers, so I am really open to all educated views.
I bought a s/hand pair of Great Heils from a friend in the UK and had a good listen to his copy of the ESS AMT-1 ( it uses the same woofers and x/over.
The secret of this speaker was using a relatively lightweight paper woofer, which many thought was **** but was key to melding with the Heil. It's for this reason that I will not use a pro woofer.
I like the idea of using the 15" Pioneer but have not ruled out using a Klipsch K33E, trouble is I can't find out it's frequency range. As long as it goes reasonably low (30Hz) and up to 2500Hz that's fine, also it's 4Ohm and has an SPL of 97.4dB
Can you explain why you want use a mid-range unit when the whole beauty of the Heils is that they are a true mid/high unit, which makes the whole x/over thing that much simpler.
ESS used to x/over at 4/600Hz but quickly changed that to 800Hz. I intend to x/over at 900Hz and use an active x/over. This in turn means that both units are totally seperate (the Heils will be slung from their own frames) so making it simple (relatively) to time align them with the woofers in their cabinets and to deal with room nodes.
The other option, which is a no-no for many because of the WAF factor is to use huge OBs and when sorted can be used as artworks - just a thought. |
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| badman |
The response curves I've seen for the heils show a dip from 1k-2k, and, apart from that, using a true mid will let me push the mid/woof XO down lower. Right now I'm using them 4th order@1k with a pair of sealed 8"s, and it doesn't suck. Another nice feature: As a true 'tweeter', the heils will be able to soak up more power: I'm all for a huge amount of headroom.
The real issue, for me, is optimized transient behavior. I want to use a mid, as I want to have a low mass transducer (10g) between the super low mass heil (1g) and the relatively heavy 100g 15".
But that's all theory. The reason I build my speakers in a modular way and use an active crossover is because I try things many many ways. |
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