Strange Sound

[macsim]

I've tinkered with guitars for years, building a few and installing pups and so forth so when I became the bassist for the church band I decided to build a bass. It's a decent guitar but I've got a phenomenon happening that I've never encountered before. I haven't done any extra shielding so I expect a little noise, i.e. the kind that stops when your hands touch the strings. That I can live with but if I rub my finger across the pickguard I get a sound that might best be described as a zipper. It's a regular P Bass style pickguard with one Dimarzio in it, 2 new 500k pots and a jack, no special wiring. I used the standard wiring diagram off the Fender website. It's more pronounced around the pup and the controls, almost disappearing at the neck end but if I rub my finger across the pickguard quickly it sounds just like I've unzipped my jacket. Anyone ever hear anything like this or have any ideas?

[Surprise Panda!]

I've read that Fender messes up their diagrams, like in their Custom Shop 60's Pickups.

[niftydog]

That's freakin' cool - I wanna hear it! Is the pick guard metallic? If not that's even cooler!

Are you perhaps coupling RF into the circuit somehow? Humans make pretty good antennas at times.

[joeyl]

yes it is called static electricity

[joeyl]

Originally Posted by Suprise Panda!

I've read that Fender messes up their diagrams, like in their Custom Shop 60's Pickups.

[macsim]

Hope this works. It doesn't sound quite as "zipper-like" in this video but this is essentially what's happening. Another weird thing - twice now I've wired the guitar and the volume pot works perfectly. Twice I've plugged in the next day and the volume pot only turns down about halfway, never all the way off. When I first put this guitar together it was fine but now it's gone haywire.

[niftydog]

Schweet! That's a new one on me.

So by the sound it's making I say joeyl is right, but does he know what to do about it??!?

My first port of call would be checking you've got good ground continuity. Volume pots can behave strangely if there ground isn't so groundy... if you get my drift. The static might be partially to blame for this as well - but I'm only speculating.

So experts, does he need to 'ground' his plastic pickguard?

[Surprise Panda!]

Originally Posted by joeyl

http://www.musiciansfriend.com/srs7/...301640/rpp=10/ Read the 7th review

[joeyl]

Originally Posted by Suprise Panda!

http://www.musiciansfriend.com/srs7/...301640/rpp=10/ Read the 7th review

for all I know, 7th reviewer could be crazy.

[joeyl]

Originally Posted by niftydog

Schweet! That's a new one on me.

So by the sound it's making I say joeyl is right, but does he know what to do about it??!?

My first port of call would be checking you've got good ground continuity. Volume pots can behave strangely if there ground isn't so groundy... if you get my drift. The static might be partially to blame for this as well - but I'm only speculating.

So experts, does he need to 'ground' his plastic pickguard?

1. wait for summer, higher humidity will cure it
2. anti static wipe before you play
3. change pickguard to a metal or a different kind of plastic

[joeyl]

Originally Posted by joeyl

for all I know, 7th reviewer could be crazy.

update I just went to get my copy that came with the CS60 pickups

The guy does not know that the pots are touching a metal plate and is grounded this way, no need to connect wires for ground, but they did make a mistake with the capacitor.

[varunkapahi]

imo it sounded kinda cool sorta try in messing with the zipper sound in a funk settings :P
better still dont fix it rather sell this bass on ebay if you dont like it!

[Jim Carr]

hmmm...I wonder if you need a foil underlay like the one that my '71 P-bass has under it's pickguard? I don't know if it helps with static charges on the opposite surface.

[KeithPas]

Have you tried running a grounding wire from the electronics to the bridge? I've never heard anything like that.

[infect]

That's awesome.. Sounds like a geiger counter!

[WayneS]

I dont think its static. If it was it wouldnt keep doing it. Once the static was discharged, it should take a while to build back up. No need to ground the plastic, its not electrically conductive.

Does it only do it with your finger? What about a pencil eraser? Or anything else?

[macsim]

Originally Posted by Jim Carr

hmmm...I wonder if you need a foil underlay like the one that my '71 P-bass has under it's pickguard? I don't know if it helps with static charges on the opposite surface.

Great minds think alike I guess. I took some regular tin foil last night and stuck it to the pickguard. Previously there was only a very small piece around the countrols but I covered the entire thing. Today I trimmed it all down, stuck it back together using a different wiring diagram and after some trial and error the worst of the zipper seems to be gone. I noticed once after playing a while that I got a bit of the zipper again. I rubbed my finger on the pg a couple of times and it went away. I think I'll take it to church tomorrow and see if it behaves. It's just so weird because I've tinkered with guitars for years and never had anything quite like this. If only I could harness the sound - instant "Poundcake" on bass! Thanks for all the suggestions!

[niftydog]

Originally Posted by WayneS

No need to ground the plastic, its not electrically conductive.

Static electricity only builds up on insulators.

[WayneS]

Originally Posted by niftydog

Static electricity only builds up on insulators.

True... but grounding an insulator will have no effect on static. Try it.