The rectifier and capacitors perform different functions in the power supply section of the amplifier, but the net result is to provide clean, smooth DC instead of the incoming AC. The rectifier changes the AC which fluctuates between about +/- 170 volts(in N. America)to either a plus or minus DC output which fluctuates from max to zero. The capacitors take this fluctuating DC and store the pulses, then release them in a smooth DC to the amplification section. The result should be inaudible hum and noise when they're operating properly.
