66 champ output power test on oscilloscope
1966 Fender Champ amp.
0.08 VAC input signal at 440 Hz
There are at least 3-4 distinct waves making it hard to accurately measure.
Using the oscilloscope gradients the peaks of the waves at max clean signal are between 4-6 volts.
Measured by a DMM, these max clean waves measure 4.0 VRMS.
This calculates to 4*4/5 = 3.2 Watts of output. Should be 5-6.