Question: I enjoyed your recent column on vintage audio equipment. I have a pair of ESS AMT 1C speakers with Heil Air Motion Transformer drivers. I have owned them since the 1970s and totally enjoy them.
How do you rate this speaker system? Is it worth keeping and is there a company that can still fix the crossovers?
San Jose, Calif.
Answer: I have not heard the ESS AMT 1C speakers, but I do know of them, though they were a bit before my time and working examples have become pretty rare. They were introduced around the same time as the Ohm F, the first mass-produced Walsh speaker. I remember reading reviews of both models in back issues of Stereo Review magazine. At the time, the ESS AMT and Ohm Walsh designs were considered breakthrough, exotic speakers, and they even looked somewhat similar with their truncated pyramid designs. The ESS AMT models did not achieve the worldwide critical acclaim of the Ohm F, but they were very well regarded high-end speakers and were noticeably less fussy to own and use than the Ohm Walsh speakers of the time.
The Heil Air Motion Transformer (AMT) is what gave the ESS AMT 1C its pizzazz. The AMT is a tweeter that looks like a square of folded fabric pleats, somewhat like an accordion. The original patents have expired and the technology lives on in new and improved applications.
You said you thoroughly enjoy your speakers, and that is reason enough to keep them going. Repairing a 1970s-vintage crossover should not prove much of a challenge for any competent audio repair shop. In fact, you could remove the crossovers from the speaker cabinets and send them to a specialist to be repaired, rather than lugging the entire speaker. You can try Speaker Exchange (speakerex.com) or Galaxie Electronics (galaxieelectronics.com) for an estimate. Both are good repair facilities for obscure speakers, and I have good experience with both companies.
I mentioned that the Heil AMT technology lives on in modern applications. Some of the most critically acclaimed speakers on the market are from GoldenEar Technology, which use a modern variant of the Heil AMT driver through their entire model line. GoldenEar calls their tweeter a "High-Velocity Folded Ribbon" driver, or HVFR. The HVFR is made of metal and has the advantage of being developed and refined in the 21st century, not the 1970s. The sound is incredibly open, detailed and airy and is a big reason the GoldenEar speakers earn such raves. If you love your ESS speakers, you owe it to yourself to give the GoldenEar speakers a listen to see how far the technology has come along; visit www.goldenear.com
Do-it-yourself speaker builders can buy AMT tweeters from www.partsexpress.com for as little as $27.50 each. Using AMT tweeters in home speaker designs gives them a unique, exotic flair and better sound as well, if the speaker is designed and assembled correctly. Parts Express even has replacement tweeters for the original ESS designs, though they can be quite expensive. The replacement tweeter for your ESS AMT 1C speakers are $350 each, but upon reflection, it seems a small price to pay to keep an original, exotic piece of audio history going.
Read product reviews by Don Lindich at www.soundadviceblog.com.