need diagnostic: nasty electrical sound

[BassMan250]

i just got a hotrodded p-bass of ebay, and it's in great condition except for one thing i noticed the other day. when i turn the tone up past halfway and play the E, A or D strings without muting the G, i get a nasty electrical-sounding crackle and buzz that goes away when i mute. could this be the fault of the pickups maybe (Seymour Duncan Basslines), or might it be something else?

[202dy]

Are you touching the strings when the nasty electrical sound is occurring?

[BassMan250]

It comes and goes, so I can't be sure, but I think it usually occurs when I'm not touching the strings.

[IconBasser]

sounds like you have a loose connection or faulty wiring or something in that pickup...

[202dy]

Originally Posted by BassMan250

It comes and goes, so I can't be sure, but I think it usually occurs when I'm not touching the strings.

If it happens when your hands are not in contact with the strings then it is normal. Here's how it works.

Guitar pickups must be grounded to operate (more or less) noiselessly. There is a wire that runs from the ground circuit in the guitar to the bridge and therefore to the steel strings. When you touch the strings you become part of the circuit. You are the path to ground. Touch the strings, it's quiet. Leave off, it hums.

[BassMan250]

OK, thanks for the help. I'll just work on improving my muting technique to minimize this.

[Turnaround]

Originally Posted by 202dy

If it happens when your hands are not in contact with the strings then it is normal. Here's how it works.

Guitar pickups must be grounded to operate (more or less) noiselessly. There is a wire that runs from the ground circuit in the guitar to the bridge and therefore to the steel strings. When you touch the strings you become part of the circuit. You are the path to ground. Touch the strings, it's quiet. Leave off, it hums.

FWIW, your body is a great big noise source. It radiates noise. When you touch the strings you ground yourself to the instrument and drain the noise to ground. It's not that you are grounding the instrument when you touch the strings, it's that you are grounding yourself.

The result is the same though - so who cares!

[PilbaraBass]

Originally Posted by BassMan250

OK, thanks for the help. I'll just work on improving my muting technique to minimize this.

sounds like a grounding and shield issue...you should get it checked out...or check it out yourself (if you've done that sort of thing before):

first off, just inspect your control cavity and pickup cavities...

1) shielding? any?
2) loose wires? any?
3) bridge ground wire? any?


while working on your technique is admirable...it will be a lot less frustrating for you if you could minimise the buzzing

[SherpaKahn]

Originally Posted by Turnaround

FWIW, your body is a great big noise source. It radiates noise. When you touch the strings you ground yourself to the instrument and drain the noise to ground. It's not that you are grounding the instrument when you touch the strings, it's that you are grounding yourself.

The result is the same though - so who cares!

Something about that seems a little odd....I wasn't aware that the human body emitted any decent amount of RFI, and if that were the case, then why does an instrument still buzz/hum when you put it down while the amp is on?

Yeah, either way it sounds like faulty grounding. There are tons of threads here about how to properly ground a bass/guitar so it won't buzz, even when you're not touching the strings.