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Buzzing polepieces

gimmeagig

gimmeagig

Feb 25, 2004
2,891
1,198
Coeur D'Alene,Idaho
#1
I have a 74 Fender Jazz with the Sadowsky preamp and I had my repair guy swap out a set of fender scns for a set of dimarzio ultrajazz pickups. Now there is a buzzing noise that wasn't there before. My repair guy is not a real electronic specialist so I want to ask here before I go back to him.
The dimarzios are humbucking pickups with two coils next to each other. So it's one coil for the E and A strings and the other for the D and G strings.
What happens is that when I touch the pole pieces on the E and A string part of the Bridge pickup it buzzes and on the neck pickup the D and G part buzzes but the opposite coils don't.
Again, Both pickups have only one coil that buzzes when I touch the pole pieces and the other remains quiet.
The sound of the bass is completely normal, full and round not out of phase sounding.
What could be the cause for this?
 
#6
narud said:
do you play p basses at all? the series wound split pickup like that will have one of the halves buzz like that when you touch the pole pieces. hows the tone though? happy with the switch?
Click to expand...
I did have a P Bass when I first started but it had EMGs in it so no buzzing.
The Ultras sound really good in my Jazz. Very punchy and clear highs too.Quite a but louder too,I think it's a good switch from the SCns. I have not played the bass on a gig yet,but so far I'm happy.
 
#10
I did call their tech department but they didn't have any advice for me. They said it's a design issue because the pole pieces are not grounded and that there's no way to hook up a wire to them.
I did notice that when I touch one of the pickups to create the buzzing sound and then I touch the bridge, the buzzing stops.
Does that help in diagnosing what might be wrong?
I had the pickups in another bass before and I'm sure that I would have noticed if the same thing was happening there.
 
#11
i can almost guarantee the pole pieces need to be grounded. While looking at the bottom of the pickup, if you can see the pole pieces, or in some cases a rectangular metal bar spanning the entire bottom of the pickup, you will want to take double sided copper shielding tape and tape that to the bottom of the pickup (touching the pole pieces). And then ground that via a wire to the bottom of the pot like any other ground. That should solve the problem
 
#12
lburton2 said:
i can almost guarantee the pole pieces need to be grounded. While looking at the bottom of the pickup, if you can see the pole pieces, or in some cases a rectangular metal bar spanning the entire bottom of the pickup, you will want to take double sided copper shielding tape and tape that to the bottom of the pickup (touching the pole pieces). And then ground that via a wire to the bottom of the pot like any other ground. That should solve the problem
Click to expand...

The bottom of the Ultrajazz pickups have two ceramic magnets and are covered in epoxy. So you cannot access the poles. The Area J has the metal plate.
 
#13
With a split coil humbucker (P or Jazz), the section that does not hum or has minimum hum when the ungrounded pole piece is touched has the start lead of the coil grounded. The start lead is the innermost winding of the coil and since it is grounded, or close to ground potential, shields the hot side of the coil from the noise you inject into the pole piece by touching it. The section that does hum or buzz is not at ground potential and the noise is injected into the coil.

If the pole pieces cannot be accessed from the bottom in order to ground them the best solution is to cover the top of the pole pieces with an insulating material...GOOD electrical tape, thin self stick foam rubber or glued on thin plastic/wood veneer. It may be cosmetically un-delightful (depending on your skills) but will definitely cut down the problem.

mech
 
#14
mech said:
With a split coil humbucker (P or Jazz), the section that does not hum or has minimum hum when the ungrounded pole piece is touched has the start lead of the coil grounded. The start lead is the innermost winding of the coil and since it is grounded, or close to ground potential, shields the hot side of the coil from the noise you inject into the pole piece by touching it. The section that does hum or buzz is not at ground potential and the noise is injected into the coil.

If the pole pieces cannot be accessed from the bottom in order to ground them the best solution is to cover the top of the pole pieces with an insulating material...GOOD electrical tape, thin self stick foam rubber or glued on thin plastic/wood veneer. It may be cosmetically un-delightful (depending on your skills) but will definitely cut down the problem.

mech
Click to expand...

As long as I have my hands on the strings that buzzing does not occur when I touch a pole piece. I might be able to live with that. Still, I guess that's a real design flaw of the ultras.The arero Js from DiMarzio don't have the epoxy back and they would probably be quieter, but they are most likely not going to have the mid 70s Marcus tone that I'm after. So for now the Ultras are staying.I heard somewhere that you could paint the pole pieces with a clear lacquer to create an insulating layer. So I dripped a little bit of super glue on one of the pole pieces to see if that would fix the buzz but it didn't.Maybe superglue is conductive and lacquer isn't, I don't know.
 
#16
gimmeagig said:
As long as I have my hands on the strings that buzzing does not occur when I touch a pole piece. I might be able to live with that. Still, I guess that's a real design flaw of the ultras.The arero Js from DiMarzio don't have the epoxy back and they would probably be quieter, but they are most likely not going to have the mid 70s Marcus tone that I'm after. So for now the Ultras are staying.I heard somewhere that you could paint the pole pieces with a clear lacquer to create an insulating layer. So I dripped a little bit of super glue on one of the pole pieces to see if that would fix the buzz but it didn't.Maybe superglue is conductive and lacquer isn't, I don't know.
Click to expand...

You don't get buzzing when you are touching the strings because the strings are grounding your body.

Super glue wont help because you don't have to make electrical connection, you just have to get your body close. It's induction that causes the noise.
 
#17
So all Ultras have this problem with one side of the PU buzzing and the other side not?
I'm so surprised that I didn't notice that when I had the pickups installed in another bass. I also had a set in a 5 string years ago and did not notice a problem.
Strange, I'm usually overly aware of anything screwy like that and if it is the design and not the wiring it must have been a problem in the other basses too, right?
 
#18
gimmeagig said:
As long as I have my hands on the strings that buzzing does not occur when I touch a pole piece. I might be able to live with that. Still, I guess that's a real design flaw of the ultras.The arero Js from DiMarzio don't have the epoxy back and they would probably be quieter, but they are most likely not going to have the mid 70s Marcus tone that I'm after. So for now the Ultras are staying.I heard somewhere that you could paint the pole pieces with a clear lacquer to create an insulating layer. So I dripped a little bit of super glue on one of the pole pieces to see if that would fix the buzz but it didn't.Maybe superglue is conductive and lacquer isn't, I don't know.
Click to expand...

on my p bass i layered on a pretty thick coat of clear nail polish. i havent had any issues since.
 

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