Big Muff: tone control causing hum

[Bucksears]

I've noticed lately that my Big Muff (with AMZ Presence Control #1) is causing a low, deep hum as I roll the tone control back. There's a sweet spot where the hum disappears, but otherwise it's there. It's not a buzz at all like a 60-cycle hum. I doubt it's a grounding issue since it goes away at a certain point.

Anyone ever have this?
Thanks,
- Buck

[petemoore]

  I doubt it's a grounding issue since it goes away at a certain point.
  Sometimes circuits don't see it that way.

[twangquack]

Sometimes circuits don't see it that way.

Agreed. This sounds similar to a time I used the modified BMP tone control (AMZ Tone/Presence #1) in a booster pedal ... it was a build where a number of wires were a bit longer than they needed to be (and I knew it, but thought I'd see how things flew) ... and I was being a bit lazy for that build and didn't use shielded wire for the input to switch, switch to board, board to output. As I recall, I shortened some wires that were messy, added the shielded wire (grounded at one end only) and it was quiet after that. This was a while back, but I seem to recall the hum did vary according to knob settings. I'm not positive, but I think that was the case. I'd look to the grounding issues first, then correct any problems that might come from excessive wire length/routing.

[Bucksears]

Interesting that this has happened with the BM tone control and AMZ Presence Control.
I'll use some shielded wire for the input/switch, switch/board, switch/output connections and see if that makes a difference.

Thanks again,
- Buck