I owned a pair of these for a year back in the seventies. Very impressive sound from the Heil drivers, unfortunately the woofers did not match them. The overall sound was not musical because of the discontinuity at crossover and the inferior quality of the woofer--slow,a bit boomy.

I wouldn't mind auditioning an all Heil speaker. Definitely great potential here. Someone mentioned that a German company. Burgmester (sp?) has been developing this design and has a rather expensive speaker out. Would like to know more about this.

Rating the AMT at 3. 5 for potential. 2 for musicality.

ESS AMT1B. I have been looking all over the net for information on these incredible speakers. Since I haven't been able to find any, I decided to make my own so here you go. I have a pair that I aquired from my father a year ago as a Christmas gift. These particular speakers have been in the family for many years and I always dreamed of the day when I would own them. Well now I do and all I can say to any of you reading this is that they are fantastic. A little history on the company. Back many years ago, ESS was manufacturing speakers for the U.S. market. They were the hottest thing going. The company has since pulled out of the U.S. market and has been marketing there speaker line in Europe. In a recent phone conversation, I was told by an ESS employee that they will be re-entering the U.S. market again soon. COOL!!! If you've never had the chance to hear these speakers, find someone that has a pair and be prepared to be amazed. The AMT1B, is a pyramid design speaker that incorporates the Heil Air Motion Transformer. As opposed to using the typical tweeter and midrange configuration, this unique design that was created in 1973,(and still considered today as leading speaker technology) uses a ribbon type system that compresses the sound and quickly fires it from the front and rear of the speaker. Distortion is non-exsistant due to the fact that there is no cone to develop resonance, and dispersion is amazing. The Heil is capable of faithfully and accurately producing high end response to 23Khz which is above what most components can deliver. For low end, the speaker incorporates a front firing 12 inch polypropelene driver, coupled to a rear 12 inch passive radiator. Low end frequency response is delivered down to 35Hz which is enough to rattle the pictures off center in my home. Power handling is rated at 400 watts of clean music power. When connected to a clean amp, such as my Yamaha, the sound that eminates from these speakers is truly Awesome. Another key feature is the build quality of these speakers. The enclosure is not made of cheap woods as in some other manufactures, and is wonderfully tight, which helps this speaker achieve it's clean, powerful, undistorted, and uncolored bass response. As you know, judging the sound of any speaker is a purely subjective thing. However, if given the chance, and soon you should be able to, please have a listen to any speaker in this company's line. You will be impressed. ESS can be contacted simply by calling information in the Sacramento California area. They are listed as ESS Labrotories.

I bought my ESS AMT 1B speakers used in '89. They're still with me in '99.They survived my college days quite well (they had as much beer dumped all over them as everything else in the house). In a really, really huge house, with a not-so-clean Luxman LV-105 amp every picture frame in the house was rattling against the wall. I guess that was important to us back then.

Now we're all a little older/wiser, and the ESS's are still going. I've been able to upgrade the rest of my stereo (B&K ST140/Marantz pre-amp, Mitsu DVD2200) and I now appreciate the AMTs for their musical quality. I'm not an 'audiophile,' but I appreciate good equipment and great sound. The HEIL driver is simply amazing to me. Every time I upgraded a component in my system, I was able to hear the AMTs reach a new sonic level. Normal front-firing dynamic speakers sound 'like a box' to me, where the AMTs really fill the room. I have mine about 3 feet away from the walls, as the combo of 12" driver plus 12" passive radiator gets muddy if you push the speakers into the corners.

If you put these speakers in a large room, and leave some room between them and the walls, the speakers just disappear. I can't comment on imaging, as the music I listen to is all studio mixed, making imaging a mute point.

My brother had B&W802 series3's matched with a Mark Levinson amp, and after listening to his rig the ESS's sounded sloppy down low; but C'MON!! what kind of comparison is that? To me, the HEIL was every bit as musical as the upper half of his 802s. For a ton less money. And you can't pour beer all over 802s and have them live. The bass could be tighter, but these speakers are at LEAST 20 years old now. I wish I was aging as well as these speakers.

My foam surrounds are starting to look a little frazzled. If you knew how rough we were with these speakers, you'd realize that they're actually holding up very well. There is a place in California that will recone ESS speakers. When I find the web address, I'll post the info.

A note on cabinet construction: These things weigh a ton! I can't imagine the cabinet having any negative effect on the sound. I've had to move apartments many times, and noone ever volunteers to move my speakers for me.

It would take a hellofa speaker to make me want to upgrade. Anything that I would replace the ESS's with is at least $2500 (ie: more that 2X as expensive)As if it's not obvious, I am really attached to my ESS AMTs. I saw in Stereo Review's '99 Buyers Guide, that ESS is indeed distributing again in the US. The suggested retail for the new AMT's was $1200 if I remember correctly. If they tightened up the bass response just a smidge, we're talking WORLD CLASS! It's unfortunate that I can't find any info on the web, and I;ve been searching for a long time. If anyone knows how to contact ESS, feel free to email me. Thanks to the fellow who posted below about how to get the number for ESS Laboratories in California.

I gotta give these things 5 stars. They sound great, refuse to die, and every time I upgrade a component, I'm rewarded with better, clearer sound. I rarely get my money's worth, but it feels like I struck gold this time!

I own the AMT1's big brother the AMT3's. They were purchased in 1974 and used in my main system until a few years ago when replaced by Apogee Stages which have since fallen to Martin Logan reQuests. However, the ESS AMT3's are still being used in a surround sound format. The Air Motion Transformer is still wonderful and working well after 27 years. The difference between the AMT3's and 1's is that the 3's have (2) 10" drivers rather than (1) and they have an added 5" mid-range driver. When marketed they were termed the "Rock Monitors" primarily due to their bass response. Although the bass drivers have been re-coned and ultimately replaced, these speakers present a superb left/right combo for surround sound -- no subwofer is necessary. An interesting aside, a decade or so ago, our home was burgularized I lost a Tandberg Reel to Reel and JVC electronics, and one of the AMT3's was moved several yards but apparently when the culprets tried to lift this well built (read heavy) speaker, it and it's sibling was left behind.When compared to my Martin Logans, I would give these speakers a 3.5 star rating. For surround purposes, I would give them 5-stars.
Related Components:
Adcom Surround Processor
Phase Linear Pre-Amp
Phase Linear 400W Power Amp
Boston Accoustics Center and Rears

ESS is, I hope, still in existence. A few years ago I cotacted the company for information about purchasing replacement drivers. Here's their address:ESS Laboratories, Inc., 11415 Folsom Blvd, Rancho Cordova, CA 95742. Phone (916) 852-0906. Now for my review.
I heard ESS 1Bs for the first time in 1979, purchased my first set of ESS 1B "bookshelf" speakers in the late '80s, and in 1995 I purchased my first ful-size AMT 1D set. Having been an audio enthusiast for all of my adult life, I have scrutinized virtually every major brand of speaker that crossed my path. None have come close to the spaciousness and clarity of the AMT series. The 1Bs and their descendants 9the 1C and 1D) are by far among the greatest achievements in the industry. One noteworthy capability of the AMT is its ability to handle high loads without breaking up, one thing that many a cone driver has succombed to in short order. Since the 1Bs ESS has improved somewhat the bass responsiveness of the series, making it a bit tighter and almost resonant-free. The cabinet construction and quality is nothing short of outstanding. Take anything, but not my AMTs!

Interesting comments on the preferred power source for ESS speakers. In fact the ESS Eclipse amp (second generation) borrowed much from Phase Linear technology. Or at least they strived for that same quality of sound. Norm

Heres a ryme for all you old timers out there.ESS was once out of sight, with a sound as clear as light!
With their sights on heaven, they went chapter 11,
down, and out of the fight!
Of course I owned them, how could any audiophile of my era not?
They were ok, and in some rooms very good, from mid up.
DR.Heil, where are you???
The good doctor, his name was Oscar!
He believed the speaker should "TALK" to the room.
He and Bob Carver were good friends!
There was an article about a Horn Loaded Heil in Speaker Builder, and I heard one and it was Quite Impressive.
I Bi-Amped my AMT. and used an electronic crossover with real steep slopes to lower crossover point on Heil.
Hell, whats a little Phase Shift among friends, right?
Try as I may, I couldnt get rid of that vocal coloration!!!
They were fun, and maybe with our technology today, one could blend the heil better.
I pulled the drivers from mine and roasted marshmellows with the cabinets!
I used the heil as a tweeter in a Ribbon array!
The powerful cast frame woofers were measured and used as subwoofers I built that an audiophile friend still owns!
Its kind of like having a dead kid who donated his organs, so that others may have life!
R.I.P.-AMT 1-B

They were ok, and only insome rooms. the woofer and the air motion transformer didnt blend too well!I used electronic crossover with real steep slopes and lowered crossover point of heil driver, and used tubes up top and phase 700 on bottom.
This was better.
I finally pulled drivers, used heil as tweeter in bipolar ribbon system and measured woofer for alignment in huge sub woofer box for a friend.
Kind of like donating organs so others can have life.
Dr.heil was good friend of Bob Carver!
Heres a ryme!
ESS was once outta sight,
with sound as clear as light!!!
Looking for heaven, they went chapter 11,
down and out of the fight!
R.I.P.-AMT 1B

It nice to see that this interesting speaker has not been forgotten. I owned a pair of 1As for several year. The Heil driver is amazing for its speed and resolution. Unfortunately, the speakers performance below the 1,000 HZ crossover was poor. Midrange was almost none existant and the bass could be rather boomy and ill-defined. ESS appeared to make no effort to blend the drivers. Hence the performance of these speakers was extremely music dependent. While they were no good for tight jazz, vocal, or classical music, they were generally great speakers for rock n' roll and electronic music - as long as there was not a lot of important musical content in the crossover region.
The Heil driver is currently being used by two other companies, Sundance and Precide. While I do not know much about Sundance, I do know a fair amount Precide. This Swiss company makes a 2-way bookself and a 2-way floorstander speaker using the Heil driver and also make Heil Headphones. The speakers are rather expensive going for about $3,000 for the bookself and $6,000 for the floorstander. If you would like to find more information about these speakers go to www.precide.ch/english.htm. The site has nice section explaining the technology behind the Heil driver and even a picture of Dr Oskar Heil himself! I believe Precide products are distributed in the US by Jason Scott Dist. I would like to hear from anyone who has heard the Precide's because I always thought that the Heil driver had great potential.

But back to the ESS AMT, I would give them an overall 3 star rating. They can be very good on the right type of music, but I believe a great speaker has to handle all types of music. It is for this reason that I ultimately replaced the ESS's.

The Heil tweeter has huge potential. Unfortunately, though the ESS company has tried incremental changes to the partnering drivers in a complete system, the results are still a disappointment. The discontinuity between the Heil unit and the ESS woofer is quite distracting. The Heil tweeter can occasionally emit harsh distortion at high volume levels. This is caused by the diaghragm "bellows" crashing into one another. ESS has sought to ammend this by glueing a lightweight open mesh material to the rear side of the diaghragm, thereby rendering the diaghragm fixed on the rear, yet free on the front side. I've yet to hear this revision, but the engineer in me says a reduction in the diaghragm movement will translate into a loss in sensitivity or efficiency.
I understand why so many people are mesmerized by the sound of the AMT1's. Such is the lure of the wonderful Heil tweeter. The system is recommendable as a background music speaker, and to those who need a bullet-proof system and listen casually.

To the serious music listener, I cannot recommend this system. They will frustrate your sensibilities. On the one hand, you will find the Heil unit giving you the best mids and highs you've ever experienced. At the same time, you will be disappointed with the woofer's lack of detail, transient speed, and transparency. If ESS ever gets the woofer right, the audio world will find a new reference, and since the technology is relatively simple, a real bargain in the offering.