Wave right before it reaches saturation Wave reaches saturation Wave reaches cut off You can see that the wave will not advance above a certain line. This must be saturation in a tube. The bottom looks different, it must be cut off. On class AB amps the top and the bottom both look the upper half of this class A amp. The class AB amp will develop cross over distortion instead. Signal is 0.05 VAC RMS at 440 Hz. Treble and bass set on 5 The clip starts when the volume on the amp reaches 7.5 O scope set at 2 volts / cm I see it max out at 6 peak volts if that 6 peak volts / 1.4 is 4.25 rms on a 5 ohm dummy load, amp expects a 4 ohm load 4.25V * 4.25 V / 5 ohms = 3.6 Watts I’ve seen this amp show as high as 4.8 Watts. It is on the low side, but I am not too concerned as it is my low powered amp.