Perceptibility of nonlinear distortions in power amplifier

Nonlinear distortions in an audio power amplifier with transistors are analyzed from the standpoint of performance in a variety of sound recording equipment. Minimization of the rippler factor has been always a major design goal, but an unjustifiably rigorous one vis-a' -vis distortions in other components of the system. Those include noise in the signal, distortion caused by wear of the tape or disk during recording and playback, and nonlinear distortions in the loudspeaker which principally depend on the dynamic range of the head. The effective overall rms ripple factor is defined, including the equivalent of all these other distortions. The actual harmonic content is evaluated on the basis of available data on the performance of some of the most popular sound recording equipment, both domestic and foreign. Guidelines are suggested for experimentally determining the amplifier ripple factor through measurement and then weighing its contribution to the overall distortion level in terms of perceptibility.