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No, but the voltages are very stable...

Actually, due to my failing vision I misread the schematic voltage on the top triode of the driver as 340V when the schematic actually says 360V, but while the B+ is 469V, a volt off what the schematic calls for, the B++ for the driver reads 380V on the meter, not 360V as on the schematic.

Still, guessing lower is better than higher, for noise.

The 120 cycle humm (just a guess) from the mid-bass bin is constant and swapping tubes one amp to the other does no change the fact that one amp produces more of it than the other, irrespective of which speaker they are driving.

Tube rush is not audible from the listening position but if you stick your head in the salad bowl it is very obvious. Again, constant and with both amps.

That eliminates pretty much everything in the chain but, both produce the same 120cps? humm just one amp a bit worse than the other and not tube or audio chain dependent as swapping tubes amp to amp makes no change and swapping amps the humm follows the amp.

Next is trying various grounding schemes. Noisiest of the two in now on the bench.




First they came for the dumb-asses
And I did not speak out
Because I was not a dumb-ass

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