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FS: ESS AMT-1 Large drivers

Thaddeus Smith

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Approximately four years old, pulled fully working from a franken-scala project I threw together and am now dismantling to pursue other things. Qty 4 drivers total, will sell in pairs and will be shipped with original OEM boxes/packaging.


Currently selling from ESS for $250/each, I'm selling these for $375/pair, shipped and paypal'd in the conUS.


Invented by the noted physicist and scientist, Dr. Oskar Heil, the ESS Heil Air Motion Transformer (AMT) tweeter uses a folded pleated Mylar diaphragm just 0.0005" thick. Its voice coil is a serpentine pattern of precision-etched aluminum, selected for minimal weight and high power handling.
Unlike a normal piston loudspeaker that excites the air by alternately pushing and pulling a cone or dome, the Heil AMT Air Motion Transformer linearly squeezes and expands its diaphragm's pleats, moving the airload at a very high velocity. Because the moving mass of the Air Motion Transformer is extremely low and the magnetic structure very powerful, this combination results in extremely high acceleration that yields amazing transients.


  • Weight: 14.5 pounds
  • Height: 6″
  • Width: 6.75″
  • Depth: 4.25″
  • Impedance: 4 ohms, Re: 3.9 ohms
  • Power: 40 Watts RMS, 160 Watts Max
  • Response: 20 kHz - 800 Hz
  • Sensitivity: 96 dB, 1 watt, 1 meter
  • Fits ESS Cabinet and Driver Models:
  • ESS: AMT-1. AMT1, AMT-1A, AMT-1B, and many more





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I remember hearing some of these years ago on top of some speakers. Their presence and the dispersion of treble was very nice.

Think Infinity started using some similar foil tweeters soon after that. But not with the ingenious Thermalright Heatsink looking housing!


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2 hours ago, jwc said:

Does anybody have a frequency response of this speaker. Does it require EQ? Is it really usable down to 800 hz?


The thread above is what spawned my interest in doing this, and Chris very much held my hand all the way through the tuning process. So I don't presume to understand it all, however, this was a raw full-range sweep of one channel @1m, with the drivers stacked and wired as recommended, in the custom "wings" discussed through the thread.




We went through a few rounds of EQ tuning per L/R channel, once with HF/Mid/Subs individually, and then three more rounds with them as a single speaker.



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7 minutes ago, babadono said:

It took TWO per side for sufficient low frequency response IIRC. If the LF cabinet being used goes higher one might be able to get just 1 per side to suffice. I mean Heil does so why not.


Correct, along with a bit of additional wave guide/"horn" ..which is why I have two pair available for sale.

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  • 2 weeks later...
On 2/12/2024 at 4:09 PM, Thaddeus Smith said:


Correct, along with a bit of additional wave guide/"horn" ..which is why I have two pair available for sale.

You are lucky the price went back up. They were available for like, $150 new for a while, which would kill your attempt at selling. I have 4 of them myself, so not need. GLWS.

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