Solving Bass Hum Problems (Grounding vs. Shielding)
Q: Why does my bass hum when I touch the strings and play in the rehearsal studio? I use SVT, Digitech multi-effects pedal and a Ibanez Roadstar II with big humbucking pickups.
A: There is some confusion out there between what happens when you have a grounding issue vs. when you have a shielding issue.
You have a grounding issue. Here’s how to tell:
- If your bass hums once you touch the strings (but is otherwise quiet), you have a grounding issue.
- If your instrument hums but becomes quiet once you touch the strings, you have a shielding issue.
For a ground issue, here is what I have learned from the researching vast the knowledge base of the internet:
All of the metal on your instrument should be connected, from the tuning pegs, through the strings, into your bridge, through the electronics, out the jack, through your instrument cable, into your amp and – eventually – through the ground of the outlet in the wall.
If you have a ground issue (and I’m assuming that it isn’t just bad wiring in your rehearsal space!), it is likely that a wire may have come loose or disconnected somewhere. I would take a look in the control cavity of the instrument and make sure that there isn’t a ground wire disconnected from the underside of a pot or the input jack.
You can also check under the bridge and make sure that there is indeed a ground wire connecting the bridge to the electronics ground in the control cavity.
If you have a multi-meter, you may be able to quickly suss out where the grounding issue is. If you’re scratching your head right now, you might take a quick peek and if you don’t see anything obviously wrong, take it to a repair person and tell him that you have a grounding issue. It should take them no time at all to find it.
For you other readers out there that may realize that you have a potential shielding issue. No Treble has a wonderful article on how to shield your bass.