I have just finished building a natural ash bodied PJ.
It has a Seymour Duncan Quarter Pounder P pickup and a Wizard '84 J pickup, with stacked volume pots.
Anyway,
I also have a P bass that has a Wizard Thumper, so I thought I'd swap the P pickups.
Quarter Pounder in the Precision and Thumper/'84 in the PJ.
I did the transplant, plugged in the PJ, and found that with both pickups on 'full' the output dropped considerably.
No problem, I thought, reverse the wiring on the J pickup and all will be fine.
(I had to do this when I fitted a pair of '84s to my Jazz).
But,
After reversing the Jazz pickup, I noticed that the output drop was still there... but only on the D and G strings.
Huh?,
So I reversed the Jazz pickup again, and sure enough the output drop was only on the E and A strings.
After much headscratching, I put the Quarter Pounder back in the PJ and the Thumper back in the Precision.... and they all work fine.
I am stumped.
Probably missing something obvious!
Any ideas?