Strange ground hum noise

[stephane]

Hi guys!

Happy new year!

I have a hum issue with my minimalistic bass recordong chain. 

P bass - bass VT pedal- audio interface

When I connect my precision straight into my audio interface there is no hum at all. 

But when I add my recently purchased Tech 21 VT Bass pedal (not the DI version), it introduces some considerable hum on the bass. It deasappears when I touch the bridge or the strings ( but it s ennoying when recording).

I tried feeding the pedal with a 9v battery but the hum remains.

Looks like a ground situation generated by the pedal. But since I feed it with a 9v battery I don't understand.

The hum appears even when the pedal switch is desangaged. Weird no? 

And when I take the pedal out of the equation there is no more ground noise.

Any idea?

I shecked all my cables.

[jrixn1]

I recently had a hum appear, and I tried every combination and permutation of basses, pedal, cables, etc; it turned out to be the standing light with a dimmer I'd just brought in from another room.

[dannybuoy]

I also had a hum issues caused by a dimmer, but only when combined with the flat EBS cables which didn't have great shielding!

Maybe try a simple DI box into the interface as a means to isolate ground loops etc?

[Skybone]

If the hum disappears when you touch the bridge, I'd guess that it was down to a bad earth connection.

[AJ567]

Could be a shielding/grounding issue in the pedal itself, or on one of your cables.

You can test for poor shielding on the pedal by wrapping in tin foil - you need to make sure that the tin foil has a good connection to the sleeve of the jacks on both of your cables. If the problem goes away, you have your answer.