Humming humbuckers...

[AlexFinger919]

Hello,

On my two guitars I noticed a strange behaviour, which keeps confusing me:

Guitar A: Two humbuckers, 3-way switch, 1 volume, shielded with copper foil. When plugged into the amp and having the overdrive channel selected, theres an audible hum when the volume pot is open. The sound of the hum changes when I turn the pot down, until it vanishes completely. When I touch any metal parts of the guitar (strings, bridge, output jack,...), the hum gets much quieter. The same thing happens when I touch any metal parts on the amp or pedal board.

Guitar B: Two humbuckers, 3-way switch, 1 volume + 1 tone; same behaviour as guitar A, except that theres no change in the hum at all when I touch metal parts, no matter if it's on the guitar itself or on the amp or pedal board.

On both guitars I checked the grounding with a multimeter and everything seemed ok. Strings/bridge, switches, pots and the shielding of guitar A are all grounded to the sleeve of the guitar cable.

Shouldn't guitar A make less noise because of the shielding?
Why do both guitars behave differently when touching metal parts on them, or even the pedalboard/amp?

Thanks for your help,
Alex

[worldrecordholder]

Check the ground in the outlet the amp is plugged into. A faulty ground in the 120v source its plugged into can cause strange things like this.

-Take the guitar to a friends house that has different amp and see if you still have the issue. You will know if its the amp or the guitar.

~JH

[LonePhantom]

Try a different power point in your place as well. If the point you are using is on the same circuit as say a fridge for example, you can get more noise.

[j.arledge]

make sure your volume is grounded to the bridge, and you also want to make sure your shielding is grounded. Make sure the ground from the input jack is making a good connection to the back of the pot.

Another thing people sometimes forget is that your 3 way switch needs to be grounded as well.

Everyone else is correct as well about your power. Sometimes older wiring in your home can give "dirty" power. Not a bad thing for most electronics but it could cause hum in your amp.

[AlexFinger919]

Thanks for your replies!

I already checked the grounding of the switch and pot with a multimeter and it seems fine!

The amp gets its power from a Furman M-10XE power conditioner, which made the hum slightly better, but not that much at all. I already tried plugging the amp into another circuit in the same room (was sure that it wasn't accidentally the same circuit), but that didn't help at all. Maybe I should try the amp in another room?

I already tested the amp at a friend's home, where it was humming too, but not so audibly. On another location I brought it to it was completely silent.

If it's because of "dirty" power, shouldn't the Furman make more of a difference?

And what I don't get too: why don't both guitars behave the same when touching metal parts on them or the amp/pedalboard?

Best regards,
Alex