ess-heil.htm

These are home stereo speakers I picked up many years ago. I have compared them to other brands costing way more than I paid and by far, they are the best sounding speakers I've owned.

A very unique feature of these speakers are the Air Motion Transformers (AMT) mounted on the top of the cabinet. This speaker operates on a different principle than conventional speakers in that it "squeezes" the air out rather than pushing and pulling the air as cone and electrostatic speakers do. Because of the very low mass of the ribbon used in the diaphragm of the AMT and the relatively small motion made, the response time is extraordinarily rapid. A problem is to find a woofer that has fast enough response time to work well with the mid-tweeter. I believe the cutoff frequencies are something like 1Khz, 1.5Khz or 2.5 Khz, switch selectable. A guy named Dr. Oskar Heil came up with this idea around 1970. The speaker company ESS (ElectroStatic Sound), now out of business, started incorporating these drivers in their line of speakers. So I'm guessing these must be about 1976 vintage?

Check out Oskar Heil's patents on the AMT at the US patent office Search for patents 3,832,499 3,636,278 and 4,056,697 and low freq transducers 4,039,044 4,107,479 and 4,160,883 Or go to Google patents and search for the above numbers.

For the second time in their life, I've had the 10" woofers repaired by the Speaker Exchange in Tampa Fl (1-800-849-6972) Ask for Randal. I highly recommend these folks. Fast turn around and professional quality. First time just new foam surrounds, this time new cones, foam and one new voice coil. I am a bit afraid of losing one of the AMT diaphragms and do not know where to get replacements. If you know of anyone dealing in such things, kindly let me know! E-mail: Marc Cozzi