ESS (ElectroStatic Sound)
ESS (ElectroStatic Sound) was an American manufacturer of loudspeaker boxes in Sacramento ( California ). It was the first manufacturer to use the Air Motion Transformer developed by Oskar Heil .
In the 1970s and 1980s a series of loudspeaker boxes was offered under the name ESS Heil .
Until 2006 it was possible to buy AMTs directly from ESS.