The two voltage divider 470k and 47k seems reasonable considering the amount of gain you'll get from those stages, but won't be the highest possible gain, so you could like to have an higher value instead of the 47k to increase the distortion.
Please note that I propose you to split the two triodes of the added 12ax7 because I guess from your description of the issue, that one of the causes is the fact that input and output of the signal on the socket are in phase, so there's some positive feedback on the circuit, so the squeal you reported.
Please note that I propose you to split the two triodes of the added 12ax7 because I guess from your description of the issue, that one of the causes is the fact that input and output of the signal on the socket are in phase, so there's some positive feedback on the circuit, so the squeal you reported.
Hello , what is your problem with bias? .. you don’t know the formula to dial ? Or something else ? Maybe you say with the noise problem when I biasing for the first time the amp ,, the problem is on the wrong side of the output transformer ,, just swap the primary wires of output transormer that it goes to the plate of el 34 ,,
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