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Originally Posted by wst3
I believe (college was a LONG time ago) the thing you describe as Class AB is actually the push-pull topology. Two class B amplifiers biased so that each one can amplify one half of the sine wave. As you described, the trick is getting the point where one turns off and the other turns on to match exactly. If they don't you get rather nasty sounding cross-over distortion!
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I had always thought class AB and push-pull were one in the same. Two Class B amps operating together to perform just like a Class A. How do class AB differ from push-pull?
Sidebar - making one half of the push-pull amp turn off exactly as the other turns on means making the design for wide temperature changes. Semiconductors change appreciably with temperature - which is why transistors are also used as temperature measurement devices. These now so common amplifiers required careful component selection so that the point of crossover did not overlap or separate for all temperatures. Class D amps must do same to avoid same distortion problems even created by room temperature change.