You said you can kill the buzz with the master. That leaves only V1 ahead of it so you can concentrate on that area.
How about with the gain all the way down, does the master still bring the buzz in and out?
Have you tried other tubes in V1 position?
And instead of clipping that 50uF cap to the plate, clip it to the other side of the plate resistor. Any effect on the buzz?
Originally posted by Enzo
I have a sign in my shop that says, "Never think up reasons not to check something."
Okay, okay.... How ‘bout this one:
Orange noise (the worst kind of noise), is also known ass 1/Sl noise due to it’s tendency to improve linearly with skill level.
So, of the schematics you received, none of them show the tone controls. But there is the d'Uur power amp drawing like in post #11. (edit: nevermind I see the pots are shown on the separate front panel board and what I thought were pots on the main drawing are connectors to the pots. Even so, the drawing in post #11 is accurate enough for everyone to work from)
With master up, does turning all tone controls down to zero reduce or remove the buzz?
Is this a circuit board amp? Are the tube sockets wired or mounted on the board? Can you post some pics of inside the chassis?
What does the owner say about the history of the fault, just showed up overnight, or appeared gradually?
So, of the schematics you received, none of them show the tone controls. But there is the d'Uur power amp drawing like in post #11. (edit: nevermind I see the pots are shown on the separate front panel board and what I thought were pots on the main drawing are connectors to the pots. Even so, the drawing in post #11 is accurate enough for everyone to work from)
With master up, does turning all tone controls down to zero reduce or remove the buzz?
Is this a circuit board amp? Are the tube sockets wired or mounted on the board? Can you post some pics of inside the chassis?
What does the owner say about the history of the fault, just showed up overnight, or appeared gradually?
yes-pcb amp
sockets are pcb
turning down tone controls doesnt really affect it---the Gain pot does
Just watched the video you posted. It sounds a lot like noise from a ballast- florescent lights, neon lights, etc. Are there any nearby? If you had say a bad input or loop switching jack or an open circuit somewhere and were near the right source, it might sound something like that. Grasping at straws a bit, I know.
Edit: Make sure your AC plug ground is making it to chassis ground.
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