Buzz when not touching metal

[Gothic]

Hello there

So, here's the problem. I've a jazz bass, which, as it was before (V/V/T) did not have any buzz/noise when not touching anything metal. I mean, at all. I decided I wanted more "hair" out of my bass, so I did away with the 250k V/V/T pots, wired both pickups in series and had just a single volume pot. And that was that.
Thing is, the bass is dead quiet when I'm touching the strings (or anything metal on it) but has quite a lot of buzz/hiss/noise when not. The noise does go away if I lower the volume significantly but not entirely, unless the volume is at zero.

The bass has that conductive paint shielding in the cavity and some foil shielding underneath the pickguard, my connections and grounds are all ok (it's a single pot wiring, after all, can't get any simpler than that!), sound is fine (awesome in series, actually, heh) and everything else seems to be working just fine.
I've even checked for continuity with a multimeter in every possible spot I could and it seems everything is grounded.

Also, this does not seem to be a "location" issue, it behaves the same at my place, at the studio, friend's house etc. No change.

Any suggestions?
Only thing I can think of is that the shielding's just... well, not enough!
Another idea was to reverse one pickup but I'm not exactly sure whether that'll make any difference at all, considering the distance between the two.

Many thanks in advance!

 

[joel the bass player]

Does the cavity shielding have a connection to the pickguard shielding, and in turn the pot? Is the whole cavity shielded, including under the pickups?

 

[Axstar]

Your bass isn't correctly shielded if you have this issue. The noise goes away because the bridge on your bass is grounded. The noise itself could be interference that your body picks up.

Don't rely on the factory shielding in your bass. I've owned a slew of MIM Fender guitars and basses. They all have some black painted splattered around the control cavity with a grounding eyelet screwed into the middle but none of it was useful for anything. I never got a continuity reading over the surface of this stuff.

 

[Gothic]

Does the cavity shielding have a connection to the pickguard shielding, and in turn the pot? Is the whole cavity shielded, including under the pickups?

Well, that I never cared to check, to be honest. I'll give it a go for continuity but I'm guessing most likely not. I'm pretty sure the pickup cavities do have that conductive paint slathered around but I'll check anyway. Thanks for the suggestion!

Your bass isn't correctly shielded if you have this issue. The noise goes away because the bridge on your bass is grounded. The noise itself could be interference that your body picks up.

Don't rely on the factory shielding in your bass. I've owned a slew of MIM Fender guitars and basses. They all have some black painted splattered around the control cavity with a grounding eyelet screwed into the middle but none of it was useful for anything. I never got a continuity reading over the surface of this stuff.

It's not my body, really, even if I leave it somewhere (on the couch or a stool or something) with the volume turned all the way up, the noise is still there.
But I do get it, I'll probably have to go ahead and try shielding everything appropriately.

Although, to be honest, it does baffle me that, when in the previous configuration (parallel, V/V/T) the noise just wasn't there at all. So much noise manifesting just because of the wiring in series and the 500k pot?

I will, however, try to reverse the neck pickup first, see if that'll make any difference.

Thanks again for taking the time everyone.

 

[Gothic]

Well, problem solved! It was indeed the shielding. I did a pretty quick job with what I had in hand (stick glue and tin foil) and lo and behold! Quiet as a church mouse! Amazing.

Thanks again for all the replies!

Oh, and by the way. CA glue does NOT bond tin foil to wood. Avoid.

 

[Killed_by_Death]

I never got a continuity reading over the surface of this stuff.

I've gotten readings as high as 500 Ohms on shielding that actually worked (G&L), but Fender shielding is usually lacking.
In summary, the shielding doesn't necessarily have to reveal zero Ohms to be effective.

 

[Axstar]

I've gotten readings as high as 500 Ohms on shielding that actually worked (G&L), but Fender shielding is usually lacking.
In summary, the shielding doesn't necessarily have to reveal zero Ohms to be effective.

I thought you were done here?

 

[MonetBass]

Resurrecting this thread because I'm having a similar issue. Opening up the control cavity, I noticed a couple of things:
1. The tech ran a single thin (uncovered) wire across all three pots to the jack ground lug
2. The wire from the left outside lugs on the volume pots is wired to the right outside lug on the tone pot. This does not match up with any diagrams I found online (see below)

It looks like that wire should be on the middle lug on the tone pot. Would this (or both points) cause the issue I'm experiencing?

 

[MonetBass]

Here's a picture of my control cavity. Everything looks good except for the two things mentioned above.

 

[sunbeast]

Here's a picture of my control cavity. Everything looks good except for the two things mentioned above.
View attachment 5213737

The wiring looks fine- the wire from pot to pot is necessary to ground the pot casings (and it is present in your pictured diagram as well), the tone pot wiring will be functionally equivalent as the diagram as well (a tone pot is wired as a variable resistor, so flipping the connections as yours is wired doesn't make any difference). To solve your issue, the best bet is thorough grounded shielding of both the control cavity and pickup cavities with copper foil

 

[MonetBass]

Thanks for the thorough explanation, @sunbeast. The pickups came with brass grounding plates which are grounded to the pots. I’ll give the copper tape a try.

 

[kyral210]

Thanks for the thorough explanation, @sunbeast. The pickups came with brass grounding plates which are grounded to the pots. I’ll give the copper tape a try.

Ensure you get the tape with conductive adhesive.