buzz on volume control only at medium settings

[isaac_teller]

Hello. What can be done to stop the buzzing when the volume knob is between 4~8? Other than that the amp is quiet. Thank you.

[pdf64]

Have you eliminated it being due to a buzzy tube, ie the stage after the vol control?

[tubenit]

Sometimes a capacitor going into the pot can leak voltage causing noise.

We might be able to help you more if you shared a schematic and a hi-rez photo of the inside of the amp chassis.

with respect, Tubenit

[isaac_teller]

I tried several tubes, didn't help. I'll try changing the cap.

[PRR]

> buzzing when the volume knob is between 4~8?

Crap is leaking into the wire from the pot wiper. Full-up the crap is absorbed by whatever drives the pot; and full-down of course the crap is absorbed by ground. But "in the middle" you have a high impedance to either end. The wire is an effective antenna for any crap in the chassis, especially crap near that wire.

So what does the wiper-wire run near?