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Loudspeaker System

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This unprecedented loudspeaker introduced the revolutionary ESS Heil air-motion transformer to high fidelity sound reproduction and achieved immediate acclaim world-wide as the major advance in loudspeaker design of the decade.

By using the ESS Heil air-motion transformer for mid and high frequency reproduction, the AMT 1 broke free of past technological theory to achieve a transparency, uncompressed stereo imaging and dynamic transient impact beyond any previous high fidelity experience.

Completely unlike any loudspeaker that has come before, and already a classic, the ESS AMT 1 opens new sound vistas to music listeners.

All forms of distortion are gone; not only sluggish acceleration that smears the immediacy of percussive sounds, but the less immediately recognized motional errors that rob brasses of their sheen, strings of their guttiness, solo instruments of their natural ease, and turn an orchestra of individual instruments into a homogenized sonic haze.

The AMT 1 combines the original ESS Heil air-motion transformer with a specially developed ten-inch woofer that has an oversize, deep-drawn frame and high gauss magnet assembly for long, linear excursion at the highest possible acceleration.

A culmination of ten prototype designs, the ESS AMT 1 woofer achieves both powerful, impactful, low frequency response and rapid acceleration for crisp transient performance that blends precisely with the clarity of the ESS Heil air-motion transformer.

Revolutionary today and the standard of comparison for tomorrow, the ESS AMT 1 is the first authentically new approach to sound generation in fifty years. Every detail of the recorded performance is revealed with a degree of purity never before achieved and completely beyond the ability of all conventional systems.

Nothing we say, or can say, will prepare you for ESS AMT l's incredible high resolution sound - sound as clear as light.


Type: 2 way, 2 driver loudspeaker system

Frequency Response: 45Hz to 24kHz

Power Handling: 350W

Recommended Amplifier: 20W (minimum)

Crossover Frequency: 700Hz

Impedance: 4Ω

Bass: 10" cone

Tweeter: heil air motion transformer

Enclosure: ported

Finish: walnut veneer, hand oiled and rubbed

Dimensions: 31 x 14.25 x 14.25 inches



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Reviewed Feb 27th, 2019 by zygotemrsmith

What a great period speaker. Use a tight high power woofer to hit the crossover transition point of the Heil !

Reviewed Oct 15th, 2018 by Raconteur


Reviewed May 17th, 2018 by sanouchev

First version with the lightweight paper cone boomer, in bass reflex.
Modified as follow for much better tone balance and efficiency:
- suppression of the original filter on the boomer, replaced with a single serial inductive ferrit coil.
- 2 internal tie-rod and bitumed internal faces
- less absorbtion fiber
I'am very satisfied, but because of the 360° emission, the sound scene is not always focused, so less accurate than a tannoy as an exemple, but much more relaxing.

Reviewed Mar 05th, 2018 by cicada

impressive speakers, they definitely have something different and you realize this from the very first moment you here them, a true specialist speaker from a different era, so efficient and alive...get a pair if you find one do not pass over, if you find just the box/cabinets with no parts, ESS is still offering today replacement drivers (heil + woofer) so you could easily rebuild them (yes, at a cost)

Reviewed Jun 28th, 2017 by VintageLyle

Does anyone need to replace their ESS AMT-1 pyramid grills?

After re-foaming my woofers, redoing the crossovers, and cleaning up the cabinets, I decided to fabricate some new grill caps because my original grills were old, faded, and broken in several places. They were the only item I was unable to find in my effort to restore these speakers.

After struggling for a while to replicate the original wood pyramid frames to the original ESS tapered dimensions, I discovered just how easy it was to assemble the new grill frames while keeping the grill fabric flat and tight all the way around. They actually appear identical to the originals except for the fabric I chose.

I also swapped out the fabric covered tops with a black reflective glass inlay. Looks really good.

There are lots of great speakers out there but these, to me, are special. It’s the clarity and presence. Yes, I overcame the bass issues and I completely upgraded the original crossovers. They still cross at 600 Hz but the original coils, caps, resisters, and internal wiring were not even closely commensurate with the quality and ability of the Heil transformer.

Since the early seventies, I have yet to hear a speaker I would rather own.

Reviewed May 03rd, 2015 by bigbmoonshine

These might be old school speakers now, but they still rock. Some of the best speakers I've heard; however, I've found the sound to be very directional - especially on the low end (9 out of 10). Besides that, they're right were they belong, (since I stole them from my dad) at my house. The sound is astonishing and crystal clear after 40+ years. After reading other reviews online, I'd have to say, if someone has a problem with the sound they're getting, it's their equipment not the speaker. We've driven these speakers HARD and there's very little, if any, noticeable distortion with full range. It might not be concrete cracking bass but I think they can be heard clearly from outer-space!

P.S. Would love to have owners manual. Looks like a xerox copy. If you see one or have one, please PLEASE please post. 1a or 1b manual as I have both.



re: AMT 1

So I have a pair of the Heil AMT-1s and know this little old lady who knew Oskar Heil. She has an AMT tweeter in a sold walnut enclosure signed Dr. Oskar Heil and 5 or 6 pages of handwritten notes on crossover design that he fixed her up with. I met her originally to set up distributed audio for her. When that was done she showed me a single AMT1 with a trashed woofer. Asked me to build her another speaker and fix that one. I explained gently to her that I would need another AMT and that building another enclosure might be tough. She took me out to her garage and handed me the other AMT, the notes and the Signed AMT and said, will this help? I was blown away. I got hold of a pair of enclosures which were empty and bought some Dayton tens that looked like they might like the enclosure and match up with the AMTs. After messing around with the crossover for a while, I got them sounding ok. Took them over to her house and set them up. I had some other work to do so left them to play. I went back to shut them off and couldn't beleive the change after they had broken in. I got lucky, they were magnificent. There was a brochure and other paperwork included. If you are interested, I can send pics and scans to you. I am also sending this info to ESS Labs in SoCal. BC

re: AMT 1

What crossover did Oscar Heil recommend? Was it a first order Butterworth (6db/octave) or higher order?
I'm rebuilding the crossovers on my AMT 1a's and was going to try a 6db/octave design with 850hz crossover point to try and keep the cost of the high end capacitors down. Is that too high a crossover frequency? Should I go for 700hz? Any documentation on Heil's crossover design would be appreciated.

re: AMT 1

Hi pongaselo

I am currenly in the process of renovating a pair of amt 1s, which I bought new in 1975. I would love a copy of your paperwork please.

Thanks Derek

re: AMT 1

Hello, I have ESS AMT1 C. I would love to have this documentation, can you send it to me?

Thank you very much!

re: AMT 1

Likewise, would love to have a copy. Does anyone know what is the minimum impedence for these? It's rated at 4 ohms but wondering how far down they could go in order to choose the correct amp for it. As long wondering what amps they had in mind, if any, when they designed those monsters from hell!

This website is not affiliated with or sponsored by ESS. To purchase AMT 1 spares or accessories, please contact the company via their website or visit an authorised retailer.