high power levels no relation push-pull configuration
Negligible non-linear distortion (sum of harmonic distortion and intermodulation products) up to the maximum rated output, at all audible frequencies from 10 to 20000 Hz;
Linear frequency response and constant output power at all audible frequencies;
Negligible phase shift within the audible frequency range;
Good transient response which, in addition to above frequency and phase requirements, demands perfectly constant gain when handling complex waveforms and transients;
Low output impedance and, inversely, high damping factor. At the very least, output impedance of an amplifier must be lower than the loudspeaker impedance;
Output power of 15–20 W for reproduction of orchestral music via a dynamic loudspeaker, or 10 W for a horn loudspeaker.Williamson reviewed contemporary amplifier configurations, and, just like Cocking, settled on a low distortion push-pull, class A, triode output stage. Unlike Cocking, Williamson believed that such a stage can deliver high fidelity sound only when the amplifier is governed by 20–30 dB deep negative feedback loop (and thus the complete amplifier must have 20–30 dB higher open loop gain to compensate the effect of feedback). Deep feedback inevitably causes sudden, harsh onset of distortion at overload but Williamson was content with this flaw. He argued that it is a price worth paying for an improvement in linearity at medium and high power levels. On the contrary, wrote Williamson, slow but steady rise of distortion to 3–5%, as advocated by Kellogg, is distinctly unwanted in a high fidelity system.
no relation