Jazz bass buzz only when tone control is on full.

[Dayeeeve]

Howdy,
This probably has been covered before but I'm going to shout about it anyway.

Got given a bass to set up etc, noticed it had a bit of a buzz that went away when I touched the metal parts. Figured I'd check the wiring had a couple of loose ground wires so I resoldered all looked good. Grounds are all there joints are nice and shiny and solid. However the guitar still has a buzz but only when the tone control is on full. If it is turned down (I.E highs are cut) the bass is silent and working perfectly. I've never encountered this before. I replaced the pot because the old one had a huge amount of solder on it but it is doing exactly the same even with a new pot.
I'm pretty stumped, I've rewired guitars and basses many times before but never had this issue. Any ideas?
The guitar is a squier jazz with a set of quater pound pickups in it. Standard jazz bass wiring is being used.
Any help would be appreciated, I had to stop working on it after rewiring it about 5 times!!

 

[Funkfingers]

Re: Jazz bass buzz only when tone control is on full.

Single coil pickups are prone to RF interference. High output single coil pickups, moreso. The hum-cancellation achieved by two unequal, reverse polarity / reverse wound single coils will always be less than one hundred percent perfect.

Rolling off some of the treble frequencies will also eliminate the worst of the interference.

 

[Dayeeeve]

Re: Jazz bass buzz only when tone control is on full.

Yes I understand that they are prone to the 60's cycle hum as they are single coils and high output ones at that, but I don't get why the buzz only goes away when I touch a metal part. Like I said before I have no buzz or noise when the tone is off and even without touching the strings etc it is quiet but when it is full I have to touch a metal part for it to be quiet. It's like it's a earthing problem but only if the tone is turned up.

I get that the single coils would produce more noise but I don't get why it has this apparent ground problem only when the tone is on full. :/

 

[Funkfingers]

Re: Jazz bass buzz only when tone control is on full.

That is an earthing issue.

The grounding issue never goes away but its most obvious consequence is negated by rolling off high frequency content.

 

[Dayeeeve]

Re: Jazz bass buzz only when tone control is on full.

I'll have another go over it tomorrow. I figured it must be that but I'm not usually that bad when I do wiring! Haha. Thanks for the input.

 

[ericmeyer4]

Re: Jazz bass buzz only when tone control is on full.

Double check that the bridge is grounded. If you have a meter you can check for continuity. That will tell you if the solders connections are good.

 

[Mincer]

Re: Jazz bass buzz only when tone control is on full.

If you are still stuck, post some pics. They will help diagnose (from afar) what is going on here. I have a Jazz bass wiring project coming up (when my pickups get here) so I am interested in this.

 

[ginormous]

Re: Jazz bass buzz only when tone control is on full.

As Funkfingers alluded to earlier, the conventional Jazz wiring allows for some measure of hum cancellation.
This happens if both pickups are set for equal volume; however, there are times when you'll want mostly the bridge pup (for example, the "jaco tone").

On my Mexican Jazz, I got a set of SDs to replace the stock pickups.
When the pickups were installed, the luthier wrapped the leads in braided wire.
He also made sure the pickups were wired correctly, as one must be in reverse polarity from the other for the humbucking to work.

Then, I shielded my control cavity, the pickup cavities and the back of the scratch guard with some copper foil tape.
I soldered the tape together at certain points, to make for a solid connection.
The copper tape connected to ground/earth by soldering a wire to the output side of the jack, and the scratch plate connected mechanically when the screws were tightened down.

All this did quiet things down rather nicely.

 

[Funkfingers]

Re: Jazz bass buzz only when tone control is on full.

The guitar is a squier jazz with a set of quarter pound pickups in it. Standard jazz bass wiring is being used.

All Crafted In Indonesia Squier Standard and Vintage Modified Jazz Bass variants seem to come with graphite paint sloshed liberally in the three cavities and connected to ground via black insulated cables. Since this is not proving sufficient, your options are to follow Reggie's example by installing shielding foil to form a Faraday Cage or to go active. (EMG-JV pickups are rather good in an all-maple Squier VM. The brighter versions of the Bartolini 9J pickups are almost as loud and they're passive.)