In 1974 Dr Heil's AMT speaker principle was granted a US patent US#3,832,499, issued on August 2. The moving mass of the Mylar Diaphragm is already very low (compared with cones and domes) and the magnetic structure very powerful, this combination results in extremely
Because of the surface area ratio it potentially moves the airload at a very high velocity, 5 times higher than the diaphragm movement itself. Hence, unlike a normal piston loudspeaker that excites the air by alternately pushing and pulling a cone or dome, the Heil AMT squeezes and expands its diaphragm's pleats likeĪn accordion. Hence with each change of direction the force will alternate between attraction and repulsion "which neatly pump air" (Lou Reed, 1967, Lady Godiva's Operation).Įxcellent animations of the Heil AMT at work can be seen The signal passes through a conductive aluminium layer, just like a ribbon tweeter,īut deposited on the pleated Mylar like the loops of the serpent (the old musical instrument with the cornet style mouthpiece). The Heil AMT uses a folded pleated Mylar diaphragm of a mere 0.0005" thickness (made where the 21st century SI units have yet to make an impact). Loudspeakers, partnered with 250mm and 300mm drive units. This tweeter (technically a "Squawker" in long forgotten nomenclature, as it extends down into the midband) enjoyed marketplace vogue in the 70s when installed in the ESS range of He developed theĪir Motion Transformer (AMT) tweeter, so called because the folded diaphragm has the effect of multiplying the surface area 5:1, much like the windings of a 5:1 transformer or a 5:1 horn.
Then, like so many of that time, turned his attention to audio.
Oskar Heil contributed to the invention of the Magnetron tube back in the ole days of radar and to pioneering work with Field Effect Transistors (FET's) that many audiophilesīelieve sound more like valves than bipolar silicon. They duly arrived, well packed, from Canada, once I had paid a stupid amount of duty well in excess ofĢ0%VAT that was demanded by that doyen of rip-off Britain, HM Customs and Excise.ĭr. Inspired youthful scribe enthusiasm to want one of those - well, a pair actually. In the olden days when oneĬould tick boxes adjacent to the names in the advertisers index of HiFi News & Record Review and send it to Link House by Freepost, the deluge of material from ESS Hence the recent ebay purchase of a pair of the Heil Air Motion Transformers, manufactured under exclusive licence by ESS. Your old scribe already has the motorcycles, LP collection and beautiful woman of his youthful dreams, so has to look wider to complete any outstanding gaps in the "I wouldn't mind one Trying to annihilate the frustration of youth and the resentment missed opportunities builds All these acquisitions (even the young mistress) are a corrective script Purchase lists in order to sate the curiosity of the intelligent enthusiast too impecunious to buy stuff at the time. I would argue that the mid life purchases are merely obsessive completion of these potential Readers are likely to have a selection of great audio masterpieces on those internal lists. Many of us have at different times assembled lists, in our heads, of the things we might buy if we could afford it. Men to entertain the delusion of order and control in the world.
The Nick Hornby novel High Fidelity (excellently transferred to the USA on the silver screen) brilliantly exposes the importance of the list in enabling The oft described (especially among women's magazines) male mid-life crisis is supposed to be a desperate menopausal attempt to reclaim the joys of lost youth, the sense of wildĪdolescent playfulness and joie de vivre, resulting in the purchase of icons of youth like classic sports cars, motorcycles, electric guitars and young mistresses. Product: Heil Air Motion Transformer tweeterĪvailability: official distributors, online stores, Ebay, Craiglist and other auctions ESS Heil Air Motion Transformer - ESS Heil Air Motion Transformer Pleats for my tweets, Heils come in handy!
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