Editing Tweeter (section)

=== Electrostatic tweeter ===
[[File:shackman-esl-mht85.jpg|thumb|right|A Shackman MHT85 Electrostatic Tweeter.]]

An [[electrostatic]] tweeter operates on the same principles as a [[full-range]] [[Electrostatic loudspeaker|electrostatic speaker]] or a pair of electrostatic headphones. This type of speaker employs a thin diaphragm (generally plastic and typically [[Polyethylene terephthalate|PET]] film), with a thin conductive coating, suspended between two screens or perforated metal sheets, referred to as stators.

The output of the driving amplifier is applied to the primary of a step-up [[transformer]] with a center-tapped secondary, and a very high voltage—several hundred to several thousand volts—is applied between the center tap of the transformer and the diaphragm. Electrostatics of this type necessarily include a high voltage power supply to provide the high voltage used. The stators are connected to the remaining terminals of the transformer. When an audio signal is applied to the primary of the transformer, the stators are electrically driven 180 degrees out of phase, alternately attracting and repelling the diaphragm.

An uncommon way of driving an electrostatic speaker without a transformer is to connect the plates of a push-pull vacuum tube amplifier directly to the stators, and the high voltage supply between the diaphragm and ground.

Electrostatics have reduced even-order harmonic distortion because of their push-pull design. They also have minimal phase distortion. The design is quite old (the original patents date to the 1930s), but occupies a very small segment of the market because of high costs, low efficiency, large size for full range designs, and fragility.