Q: 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 these speakers? Are they worth keeping, and is there a company that can fix the crossovers?
A: I have not heard the ESS AMT 1C speakers, but I do know of them. They were introduced around the same time as the Ohm F, the first mass-produced Walsh speaker.
I read reviews of both models in back issues of Stereo Review. At the time, the ESS AMT and Ohm Walsh designs were considered breakthrough, exotic speakers. They even looked similar, with truncated pyramid designs. The ESS AMT models did not achieve the acclaim of the Ohm F, but they were highly regarded and were noticeably less fussy to use than Ohm Walsh speakers then.
The Heil Air Motion Transformer (AMT) is what gave the ESS AMT 1C its pizazz. The AMT is a tweeter that looks like a square of folded fabric pleats, like an accordion. The original patents have expired and the technology lives on in new applications.
Because you enjoy your speakers, that is reason enough to keep them going. Repairing a 1970s-vintage crossover shouldn’t be a challenge for a 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. Try Speaker Exchange (www.speakerex.com) or Galaxie Electronics (www.galaxieelectronics.com). Both are good repair facilities for obscure speakers, and I have had good experiences with them.
I mentioned that the Heil AMT technology lives on. Some of the most critically acclaimed speakers on the market are from GoldenEar Technology (www.goldenear.com), which uses a modern variant of the driver. GoldenEar calls its tweeter a High-Velocity Folded Ribbon driver. The HVFR is made of metal and has the advantage of being developed and refined in the 21st century. The sound is incredibly open, detailed and airy and is a big reason that GoldenEar speakers earn such raves. If you love your ESS speakers, give the GoldenEar speakers a listen to see how far the technology has come.
Do-it-yourself speaker builders can buy AMT tweeters from Parts Express (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, although they can be expensive. The replacement tweeters for your ESS AMT 1C speakers are $350 each.