Step-up circuit for driving full-range-element electrostatic loudspeakers

An audio step-up circuit for driving full-range-element electrostatic loudspeakers of the type having a flat conductive diaphragm suspended in spaced, parallel relation between a pair of opposed, acoustically transparent stator plates comprising, in combination, a first audio signal voltage step-up transformer for signal voltage step-up at lower audio frequencies of the 30 Hz to 20 kHz audio frequency band, a second audio signal voltage step-up transformer of substantially lesser turns ratio as compared with said first transformer for signal voltage step-up at higher audio frequencies of said 30 Hz to 20 kHz audio frequency band, means for connecting the primary winding of said second transformer to a low voltage, low impedance audio signal source, said connecting means including an adjustable series-parallel RC network in series with said primary winding of said second audio transformer, the secondary windings of said transformers each being center-tapped with the center-taps returned electrically to a common low potential "ground" return for push-pull output operation, a capacitor connected in series with each of the secondary winding terminal leads of said second transformer for capacitive coupling to the stator plates of an electrostatic loudspeaker and a resistive element connected in series with each of the secondary winding terminal leads of said first transformer for resistance coupling to the stator plates of the electrostatic loudspeaker, whereby the output circuits of said first and second transformers will be in parallel-bilateral interconnection for cooperatively feeding the stator plates of the electrostatic loudspeaker, and means for supplying a substantially constant high voltage electrostatic charge to the conductive diaphragm of the electrostatic loudspeaker.