The design of electrostatic loudspeakers

A method of compensating for a reduction in output sound pressure level of an electrostatic loudspeaker, caused by front to back cancellation effects, using a resonant circuit and filter connected between the output of the audio power amplifier ( 8 ) and the input of the electrostatic loudspeaker transformer ( 1 ). The resonant circuit includes an inductor ( 3 ), capacitor ( 4 ) and resistor ( 5 ), the values of which are chosen so that the shape of the tuned circuit response curve closely mnatches the shape of that part of the loudspeaker response curve that requires compensation. The resonant circuit and filter may be combined with a metal oxide varistor or similar non-linear device to limit over-voltages.