What is the purpose of RC components to ground in this class AB amplifier?
What is the purpose of RC components to ground in this class AB
amplifier?


Q1 is a common-emitter stage that supplies all the voltage gain in the circuit. Normally, for a common-emitter stage, its voltage gain would be R7/R6 but, with the capacitor added across R6, the voltage gain (and distortion) will be increased due to the reactance of the capacitor being small in the mid-band of frequencies.

Note for Kyle B: it doesn't result in negative feedback when you add the capacitor - it results in a localized reduction of negative feedback around the Q1 stage. Neither does it improve linearity - it actually reduces linearity and creates more signal distortion.