Grounding/hum issue

[Lester87]

I have a true bypass looper (in - out and send -return) which causes quite a bit of hum, I've opened it up and I believe it's not grounded properly. How can best ground it? Or could something else be causeing the hum?

[uOpt]

The metal case, if any should be grounded. If the case is not metal you should have shielding foil or similar.

If the hum persists you need to check what it on the other side of the cables connecting it. If the devices there are all connected to A/C power you might not have a shielding issue but a ground loop with potential difference. In that case you cut ground from one of the cables at this box.

[Lester87]

Yes it is a metal case, how/from where do I ground it?

[Bobster]

Hi Lester,

Just a few questions....

1. Does it hum when your hands are on, or off the strings, or just all the time?

2. Any loose wires?

3. If you have a multimeter, do you have a ground from the bridge to the pots and control plate?

Thanks

[Lester87]

No the bass is fine, it's just the loop pedal that's causing the problem. I've tried my pedal chain with and without the looper and it's only causing hum when the looper is in the pedal chain.

[uOpt]

Originally Posted by Lester87

Yes it is a metal case, how/from where do I ground it?

Normally it would be grounded via the plug on the cable to the amp.

However, that might not happen for a number of reasons. You should check with an ohmmeter.

[SGD Lutherie]

Do you have it plugged into two amps? Or are any of the effects AC powered?