Eminent LFT-6, Installation Manual, Page: 10 / 25

10
The electrostatic starts with a very thin (half mil or less) diaphragm made
of mylar or a similar material, to which a light coating of mildly conductive
substance such as graphite has been applied. This diaphragm is suspended
on a rigid frame and sandwiched between two stationary conductive grids
(usually perforated metal plates) called stators.
FRAME
REAR STATOR
RESISTOR
TRANSFORMER
+
--
TO
AMPLIFIER
TO BIAS
VOLTAGE
SUPPLY
[PERFORATED
METAL PLATE]
FRONT
STATOR
CONDUCTIVE
DIAPHRAM
A DC charge of high voltage (in the thousands of volts) but very low
current, known as the bias voltage, is applied to the conductive diaphragm
and kept constant. A step-up transformer is introduced to increase the
usable voltage of the amplifier's output (while simultaneously decreasing
the current), and the two ends of the transformer's output coil are
connected to the two stators.
As the amplifier produces a continuously varying AC voltage, (the
amplified music signal), the charge on the two stators will also
continuously change in synchronization with the music; and since the two
stators are connected to two different ends of the transformer's output, one
stator will take on a predominantly negative charge at the same time and to
the same extent that the other stator takes on a predominantly positive
charge. The constant-charge diaphragm will thus undergo a continuously
changing state of attraction to and repulsion from the two stators as their
polarization changes, and it is this motion that excites the air to the front
and rear of the speaker and produces sound.
Electrostatic
Loudspeakers