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RE: Premature judgement

Noise went down when I moved the 1K resistors AND the ferrite beads back to where they were when this saga started. For what it's worth, now that the levels are lower, I can trace the noise to the top tube in the totem pole that feeds the screen. That tube has no direct connection to the 1K resistor, which of course supplies bias and signal to the grid of the bottom tube in that totem pole. But I can see that most remaining noise is on the 7.5M resistor that attaches from the input stage to the cathode of the top tube and then to the screen outputs. (I assume it's feedback, but I could be wrong.) Also, this is with nothing attached to the output. Could it be that loading the amp would reduce the electrical noise?

And yes, oscillation or at least noise, is a known problem with these amplifiers. If I did not love the sound of the system so much, I would not put up with it. But I do, and I am. Roger Modjeski had mods for the amplifiers, among which was using tubes in the input stage. But apart from that, I don't know what he did to them. Too bad, for us owners and for him, that he is no longer around.

I have a good schematic (bought from RAM) which I might be able to send to you, if you're interested.

I think I can give it a go on the speaker now.

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