Electrostatic
From Wikiphonia
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Electrostatic Driver Principle
Electrostatic drivers work by suspending a sheet of thin material (usually Mylar plastic), held under tension and coated in an electrically conductive material, between stators. Stators can be made our of perforated metal or copper plates, wire mesh or plated (with Gold for example) perforated printed circuit board material. The diaphragm has a high biasing voltage applied over it and by inducing changes in the charge field applied to the stators, the diaphragm is pulled toward one stator while being pushed away by the other, and vice versa for motion in the opposite direction.
I will illustrate the process by giving an example. Lets say the diaphragm has a high positive biasing voltage applied it, and the stators are alternately charged with a positive current and a negative current, based on the varying electrical audio signal. When the the front stator is positively charged and rear stator is negatively charged, the diaphragm fluctuates toward the front stator, and when front stator is negatively charged it fluctuates toward the rear now positively charged stator. In this way, it precisely reproduces the recorded pattern of air fluctuations.
It is important to note that motive force is applied over the entire diaphragm at once and this create a uniform motion, thus reducing the wobble and therefore the distortion. Because the diaphragm has such a low mass, it responds very quickly and precisely to changes in the audio signal. This makes for extremely accurate sound reproduction with superb transient response. The problem with such design is the limited excursion of the diaphragm, therefor to produce sufficient bass electrostatic drivers must have very large radiating surface when compared to dynamic drivers.
Electrostatic driver is a true dipole and it radiates sound when diaphragm moves in both directions. Special amplification is required for electrostatic drivers because of their high voltage nature.
Brochures
Stax 50th Anniversary - 1988 Brochure
 Stax 1988 (Page 1) |
 Stax 1988 (Page 2) |
 Stax 1988 (Page 3) |
 Stax 1988 (Page 4) |
 Stax 1988 (Page 5) |
 Stax 1988 (Page 6) |
 Stax 1988 (Page 7) |
 Stax 1988 (Page 8) |
 Stax 1988 (Page 9) |
Stax, Koss, Sennheiser, Sony and Micro Seki Brochures
 SR-Sigma brochure |
 SR-Sigma brochure nr.2 |
 Stax Lineup brochure |
 Stax Lineup brochure nr.2 |
 Koss ESP/6 Brochure |
 Sennheiser brochure p2 |
 Micro Seki MX-1 brochure |
 Sony ECR800 and ECR600 sales brochure |
Pictures of drivers
 Stax SR-202 driver |
 Stax SR-404 driver |
 Stax Lambda Nova Signature Driver |
 SR-Lambda driver |
 Stax SR-XMk3 driver |
 Stax SR-Omega drivers, photo by spritzer |
 Stax SR-007 driver, photo by Spritzer |
 ECR880 Driver diagram |
 ESP/950 driver in housing, photo by AudioCats |
 ESP/950 driver closeup, photo by AudioCats |
 ESP/950 driver out of the housing, photo by AudioCats |
 ESP/950 driver cable connection closeup, photo by AudioCats |
