I think I may have a grounding issue and I don't know where to go from here. I am running a 1969 yorkville tube amp through an epifani ul1x12 with a NYC epifani style speaker. (Tweeter too) I love my 1976 p bass tone through it but every time I let go of the strings I get buzzing. If I turn the tone knob down it goes away and bye bye cool tone. I took my bass apart once already, reset the bridge and grounding wire, and a friend helped me replace the jack with helped but didn't totally get rid of the problem. I have tried a vintage silver tone and a modern modulus and no buzzing. Is this a single coil issue? Is it just the tone pot? If I need to replace anything what do you recommend. Thank you!
While I know nothing about these things and my opinion on the matter is completely useless, isn't it something about interference from other electronics around the bass/amp? Wiring in the walls and your tv and your toaster and so on? I know on my setup sometimes it's there and other times the buzz is completely gone.
Yeah, shielding with copper foil in both the control cavity and pickup cavity will probably help quite a bit.
There's a thread here on it: http://www.talkbass.com/forum/showthread.php?t=159191 The gist of it is that you take out the electronics/pickups and line all the cavities with copper foil tape (or conductive paint), as well as the back of the pickguard. Then you make sure all of the foil is connected, to itself and to ground.
Typically P-basses in the late '60s and early '70s had a layer of thin metal shielding under the portion of the pickguard that held the pots and output connector. Has yours perhaps gone missing?
If it had, the bass probably wouldn't work as Fender used to use it as the ground connection between pots. I think Squier still does that.