Buzzing with changing volume

[isaac_teller]

Hello. I built a 5E3 style circuit with 6JB5's in the output, 6SL7 and 6SZ7. It is very quiet except for a buzz that starts at about 4 on the volume, increases to max at about 5-6 and goes away at 7. What could cause this? The signal leads are shielded and the pot bodies are grounded. Other than that it sounds great. Thank you.

[Jennings]

Maybe the pot itself?  Try taking a few measurements in the sweep, and a spray of pot cleaner/isopropanol just in case?

[st]

Sounds like a ground (internal ground loop) problem... Could you give any information on  layout (especially ground scheme)? Is the hum still within acceptable limits or is it just too loud?

[PRR]

> a buzz that starts at about 4 on the volume, increases to max at about 5-6 and goes away at 7

The lead from the wiper to the next stage is picking up buzz from "somewhere". When full-down or full-up the buzz is shorted-out; at mid-way (not near either end) the buzz is maximum.

Shielding normally makes this insignificant. Re-examine that shielding. The shield should return to the ground of the stage it is going to, normally directly TO the stage's cathode RC network ground.