If the amplifier has a -3 db point that is a frequency lower than that of the timing constant of the power supply, then the amplifier can modulate the supply, which results in IM distortion amongst other things.Ralph, let me see if understand what you wrote above. I'm getting confused because w.r.t. the amplifier you are using frequency & w.r.t. the power supply you are using timing constant. Freq & timing constant are reciprocals of each other.
So, what you are saying is that for motorboating to occur the time constant of the amplifier has to be higher ("If the amplifier has a -3 db point that is a frequency lower than...") than the time constant of the power supply. Correct?
So, basically, the bandwidth of the power supply should always be lower than the bandwidth of the power amp. Correct?