So I've got this '64 Vox AC4 which I started fixing about a year ago but then had to move house and I've only just found it again. It has this really weird problem where the speaker cone moves in and out at the same rate as the tremolo oscillation, and something inside the EL84 (not the heater) is glowing on and off slightly at the same rate. I've tried replacing all of the valves to no effect, so it's a cap or resistor somewhere. It's almost as if it's trying to output the tremolo oscillation as an audio signal, if that makes sense? It's this circuit by the way, which I've badly edited in MS Paint because it's the weird version where the tone control is wired up differently. Does anyone here have an idea as to what could be up with it? Let me know if you want any more details or voltages or anything, any help would be greatly appreciated. Many thanks in advance!
