Push-pull audio amplifier theory

Assuming nonlinear tube characteristics, this paper presents: 1) a single mathematical analysis of instantaneous relations applicable to all classes of operation of push-pull audio vacuum tube amplifiers; 2) a mathematical derivation, applicable to all classes of operation, of the composite load line equation and a study of the amplifier frequency response both at medium and low frequencies, with third and higher odd-order effects neglected at low frequencies; 3) an analytical method for finding the maximum magnitude of class AB1and AB2grid bias beyond which appreciable non-linear distortion occurs; and 4) a single general condition for matching the load to the tubes irrespective of the class of operation, and the interpretation of this condition for each case.