Dr. Oskar Heil invented this tranducer and it was first used commercially in 1970 (the incredible sounding ESS AMT-1.) More recently, Mark & Daniel Loudspeakers have gotten rave reviews for their line of solidly constructed, and great sounding loudspeakers, which use these drivers -- although much improved and updated with modern materials and computerized design technology. I just wish I found them more attractive
In any case, I thought I'd head off any implications (through ommission) by ML that they started this party. They didn't. Nevertheless, I think this is a long neglected technology which should have been ressurected ages ago (when the patents ran out?) And I wish them great success with it.
There were reasons (both fiscal and technical) why the technology never took off in it's original incarnation (similar to why they had to shelve electrostat progress until they could use mylar instead of cow gut!) and the main technical obstacle was low output -- now greatly improved. In my opinion, they will never replace the awsome performance of an electrostat, due to the size limitations of the technology, but unlike ribbons, their compact size may enable them to finally live up to their promise as a last nail in the coffin of the always inadequate dome tweeter and midrange drivers.
And for those audio newbies who imagine "the old days" are everything prior to 1980
I offer this link for your education and enjoyment:
Air Motion Transformer - Wikipedia, the free encyclopedia