I've done a significant number of searches here and on the web in general to find an answer to this question with no luck so far, so here goes....
I have put two P-Bass pickups in an experimental parts bass. The pickup in the original position is a Seymour Duncan Antiquity II / 60's, and the bridge position pickup is a stock MIM P-Bass pickup from around 2008.
When I wired these up, I went with two volume controls and no tone control at all (stack knob setup coming later). Both p/u's have the two coils in series just as they were originally made.
Here's the issue and the question; When I wired these up, I observed polarity on each the same, white is signal and black is ground. When I first tested the bass, each p/u sounded good solo, but it was extremely thin with both on. It sounded exactly like you would expect with two out of phase pickups. I reversed the polarity of the MIM stock p/u in the bridge and now both sound good solo and both sound good together.
Q: Is this normal due to the reverse wiring of ONE of the P-bass p/u's coils OR do I have two P-pups that happen to be reverse polarity from each other?
Is it likely that each p/up has reverse winding as normal, but a different coil is reverse wound in each pup?
It's a problem that is solved, but I'm trying to figure out what I have here for future reference....