Grounding issue??

[Jukers]

I just wound a p bass for a friend of mine and I have a problem that I've never heard before. I'm pretty sure I've got it wired correctly because I wired it with a standard p bass wiring and grounded everything!! But my problem is that when I rub my fingers up and down the string, without pressing or playing the string itself, I get this scratching sound that sounds like an electronic scratch.

When I play the bass in my shop, or my amp (anything at my house), I have to crank up the volume and highs of the amp/mixer and I can barely hear it. At my friends place it's extremely evident whatever volume you play. But with both venues, if I turn the tone all the way down I can't hear it at all.

Has anyone ever had this happen before? and how can I test if the ground at his place is just bad without buying a new/different meter?

[dcoyle]

I'm not sure what your problem is, but I doubt it is the ground at his house. If you are really sure of no errors on winding or wiring, I would look for something that touched when you reassembled the bass. Does the resistance to ground read what it should?

Are the pickups out of phase?

Dan

[Steve Conner]

I guess the control cavity isn't shielded, and your friend's house just has a lot of noise.

If the electronics in a bass or guitar are unshielded, it relies on the player's body as a shield against noise, but this only works when it's grounded by a hand touching the strings. When you run your finger gently along the wound string, you're rapidly making and breaking contact with it, so the noise gets turned on and off as rapidly, and that causes the scratching noise.

So if the noise bothers him, I'd recommend you try shielding the control cavity with foil tape.

[Jukers]

I'm not sure what your problem is, but I doubt it is the ground at his house. If you are really sure of no errors on winding or wiring, I would look for something that touched when you reassembled the bass. Does the resistance to ground read what it should?

Are the pickups out of phase?

Dan

Resistance it good, and the pickups are out of phase (humbucker style).

[Jukers]

I guess the control cavity isn't shielded, and your friend's house just has a lot of noise.

If the electronics in a bass or guitar are unshielded, it relies on the player's body as a shield against noise, but this only works when it's grounded by a hand touching the strings. When you run your finger gently along the wound string, you're rapidly making and breaking contact with it, so the noise gets turned on and off as rapidly, and that causes the scratching noise.

So if the noise bothers him, I'd recommend you try shielding the control cavity with foil tape.

That is exactly the sound that I was trying to describe. Yes!!! and that fix also makes sense. I'll give it a try asap!!

[Jukers]

Hard Spot

So I shielded the cavity and nothing new. When you ground the instrument by touching it everything is fine, a.k.a. bridge, jack, strings. But it's only when you rub your fingers lightly while not grounding by touching anywhere else. So that leads me to believe that it's not a hum oriented issue with sheilding and what not, but it's something else. Is it possible that the strings are just not grounding well to the bridge??

So far I've tried a different cap, grounding and not grounding the tone (but there's an aluminum shield under the pick gaurd so that shouldn't matter), shielding the pickup and control cavity, and beating my head up against the wall.

Different strings? Different bridge?

[David Schwab]

Have you tried a different cable between the bass and amp?

I had an issue like this once and fixed it by running a second ground wire from the back of the pots to the jack. Then it was dead quiet. I'm not sure why it worked, but it did.

[Jukers]

rock

nothin seems to work. i think i'm just gonna start from scratch...

[the great waldo]

nothin seems to work. i think i'm just gonna start from scratch...

It could be static, Try rubbing the scratchplate quickly with your hands and see if you get a build up of noise. Some of the new pvc scratchplates are really bad for static compared with the old celluloid ones. Try the guitar without the scratchplate and see if that makes a difference. As a last resort you could try Elixir coated strings.

Cheers

Andrew

[RedHouse]

It could be static, Try rubbing the scratchplate quickly with your hands and see if you get a build up of noise. Some of the new pvc scratchplates are really bad for static compared with the old celluloid ones. Try the guitar without the scratchplate and see if that makes a difference. As a last resort you could try Elixir coated strings.

Cheers

Andrew

Yes I'd bet it's just that, it's a common problem with scratchplates.

You can get rid of that by glueing a piece of copper foil to the back and soldering a ground lead to the ground on the controlls.
(the aluminum stick-foil doesnt work for this)

[Jukers]

FINALLY!!!

I've got to admit that I when y'all said "scratch plate", I figured that y'all were talking about the pick guard. I'd never heard anyone call it a scratch plate before... Anyways, I finally fixed it!!

After trying to ground, unground, two grounds, new pickups, new pots, different wire, shielding everything.... all I did to finally fix it was replace the bridge itself!!! I was amazed.

[RedHouse]

I've got to admit that I when y'all said "scratch plate", I figured that y'all were talking about the pick guard. I'd never heard anyone call it a scratch plate before... Anyways, I finally fixed it!!

After trying to ground, unground, two grounds, new pickups, new pots, different wire, shielding everything.... all I did to finally fix it was replace the bridge itself!!! I was amazed.

Glad you got it fixed.

Yeah the words scratchplate and pickguard are often used interchangeably but originally a pickguard refered to a piece that is attached off the face of the body like old arched top acoustics or an ES335 or Les Paul, where as a scratchplate affixed directly to the face of the body like on an dreadnaught acoustic guitar or a Fender type electric guitar.