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Half of Precision pickup out of phase


Mylkinut
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Hi all,

I recently aqcuired a 70s Precision which has (I think) a DiMarzio Ultra Jazz fitted at the bridge. Each pickup sounds fine individually, but having them both on full makes the E and A strings sound out of phase. D&G both sound as expected, so I'm assuming one half of the P pickup is out of phase with the J pickup.

I've currently got it wired VVT. One weird thing is the out of phase effect is strongest when I have the Jazz on full and the P at about 95% - still only on the E&A with the D&G unaffected.

I've got another P with an added J pickup that doesn't have these issues - any ideas?

Cheers

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6 hours ago, paul_5 said:

I had this - I ended up swapping the wire that connects one half of the pickup to the other with the wire that goes to the hot/ground part of the pot and it sorted the problem.

Cool, I'll try that - did you get any buzz when soloing the P pickup?

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I had to do something similar when I swapped out a PJ's J PU. 
 

The split P pickup should be wound RPRW (Reverse Polarity Reverse Wound) so it works as a humbucker.

It is possible it is incorrectly poled with the two halves wound out of phase but the magnetic poles the same. If so, half of it will always be out of phase with PU2 giving the symptoms you report on two strings.

Check to see if the P pickup is correctly wired / magnet poled by connecting a meter on ohms range across the pickup and pulling an allen key off the pole pieces  - this will show the true phase of the PU.

 

Reverse the phase of PU2 and try it - OR - do as paul_5 suggests and reverse half the P pickup (this looses the humbucking as a single PU)...

Ideally a two PU bass should have the two PUPs wound RPRW so they hum cancel when combined?

Edited by Bigguy2017
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Thanks for the replies everyone, all very helpful. I ended up doing as Paul suggested as a quick fix and it worked perfectly. I'm getting buzzing from the P pickup as expected, but I can live with it - it sounds so much better now.

Thanks again!

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