My most loyal readers will know that I have a place in my heart and my living room for the Heil Air Motion Transformer, specifically the big dog AMT1. This is a special type of transducer, similar in some respects to a planar speaker (Magnepan, others) but with a twist- or a fold. Instead of moving in and out, they compress or expand folds. This allows dramatically more surface area to apply pressure to a given amount of air and thus provides significantly more output than a conventional speaker with a given amount of diaphragm motion. In other words, the folding and compression scheme gives you a driver that can act much bigger than it is.
I've worked with the Heil AMT1 for some years now, and currently use them with a dipole waveguide arrangement. Upon hitting the T.H.E. Show Newport Beach in 2011, and again T.H.E. Show Newport Beach 2012, I spoke with Rico "Ricky" Caudillo who runs ESS. Having purchased the business and inherited all the classic designs, rights, and goodies associated with Heil. There were interesting developments in their designs as I saw at the Newport show.
I found myself in his neck of the woods as part of my day job, and gave him a call. Ricky graciously accommodated my last minute request to take a peek around for Enjoy the Music.com, and so I drove over to their location in South El Monte, CA. We popped into their main "casual listening" space and there were several models, along with a selection of gear to use with them for casual evaluation and prototype listening. There is a more formal measurement and testing space in an acoustically treated room.
After gawking at some of the oodles of speakers and drivers everywhere
We took a look at the diaphragm assembly. The voice coil etching process is done via machine, with ESS's special sauce method of voice coil winding, then folded and assembled via hand.
Along with the variety of goodies being currently worked on, there were classic versions and prototypes tucked away in every corner.
Not surprising, and the tinkering mentality lives on there today with lots of prototyping. Heil has a wonderful legacy of invention from the big man Dr. Oskar Heil to Nelson Pass who worked at ESS in the 70s as a speaker designer.
Here are two versions of prototype Heil air motion transformer woofers. Similar devices are made by Danish Sound Technology (DST), who manufactures Vifa, Peerless, and Scan-Speak drivers. You can see that one is made with conventional midrange drivers.
Along with the classic prototypes there was a variety of neat old-school testing gear, schematics, and other various goodies.
Lest you think they are a museum only, I can assure you that they do indeed build finished speakers here. Anyone who's spent any time around hi-fi has seen these Heil classics- updated now with improved drivers and crossovers.
ESS Heil is working with spiderless driver designs for a number of drivers, some small neo midranges, 10” woofers, and I believe a 6x9 mid-woofer design.
Another old-school design with a personality!
Much of the ESS Heil business is in repair of the classic loudspeakers, and so they spend a goodly amount of time re-coning and restoring vintage Heil speakers. You may remember my article Repairing Damaged Speakers/Drivers.
The time I spent there was interesting, full of good work and interesting history. Am hoping to have a chance to play with the smaller models as seen at T.H.E. Show Newport 2012 show and possibly do a horn similar to the one I did for the bigger ones. Always more to build!
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