Fender Silverface Champ tone stack bypass and dropping of signal at high volume

[Helmholtz]

Sorry, yes I missed that this amp has a 3.2 Ohm output.

Best repeat measurements at 600mV input (or the max level before signs of clipping) using the speaker.
Keep measuring time short to protect the speaker and your ears.

With "calibrated" I meant the vernier knob of your scope.
You could also use your DMM to measure RMS output voltage (as long as the signal is clean).

[Delta362]

I'll have to get back on this later in the week. Spent pretty much all day off and on with this because of a wild goose chase that was self induced.

In the meantime, I'll order a 4 ohm dummy load. I apologize for not realizing my test speaker cabinet wasn't the same impedance as the Champ stock one. FYI, I added a 1/4" speaker jack for this instead of the RCA jack that was there originally. All mods were requested by the owner.

And thank you for clarifying the vernier knob on the scope. I'll double check it next time.