Hum when I turn the guitar down

[nee]

Greetings!

I'm playing around with an overdrive build which is sounding good, but I'm getting a lot of hum when I turn the guitar down. When the guitar volume is on 0 or 10 everything is fine. Turning down from 10 and the hum increases, stays fairly constant, then disappears again as I hit 0.

There is a fair amount of gain in the circuit, and a fair few wires going to and from pots and switches and jacks, and the whole thing is unshielded on a breadboard, but perhaps this is a well-known phenomenon that  someone has experienced before?

The guitar is a Les Paul with good electronics btw.

Many thanks!

IanG

[ambulancevoice]

my guitar does this as well, exactly as you describe it
i think my guitars volume pot is the problem
try your guitar with another distortion, at max, just the distortion alone
and try your volume pot then
if it does it again, than its the pot, just replace it with another 500k

[lvs]

With the guitar volume maxed, the resistance that "terminates" the signal cable at the guitar side is in the order of magnitude of a pickup, around 10K.
With the volume shut off, that resistance is zero.
With the volume pot at it's resistive midpoint, that resistance is roughly the pot's resistance divided by 4. For example if it's a 500K pot, that is 125K, making something further downstream that is not well shielded, more susceptible to hum.

That's what might be happening imho.

[Beros]

Try changing your guitar cable. Worked for me.

[GibsonGM]

Any DC riding along your signal path with your breadboarded circuit? If it doesn't do it with another pedal, that's what I'd at least check for....can make for some weird hum!  The pot would also most likely get scratchy sounding if that was the case.
Just something else to check...