Originally Posted by
Simon Barden
Pickups from the same manufacturer should come with the same overall polarity, whether humbuckers or single coils, so that a two pickup combination wired in parallel or series will be ‘in phase’. Mixing pickups from different manufacturers risks the signal polarities being reversed, so you get a thin ‘out of phase’ sound when two (or more) pickups are selected.
I presume you want to achieve a RWRP pickup so that a two pickup selection is hum cancelling? And both pickups currently have the magnets arranged so the upper pole pieces are both N or both S?
This is when it might be best if you can swap the standard braided single conductor output wire P90s normally come with for a twin conductor shielded cable. The shield connects to ground at one end and the pickup base plate at the other, allowing you to reverse the pickup connections and wire for series/parallel and also incorporate a polarity switch for the mid position.
As far as I can make out, there should be no meaningful difference between the signal produced by just swapping the output wires round with the magnet flipped. If you look at a small section of the coil windings on a pickup that has been wound ‘backwards’ compared to a ‘forward’ wind (based on the length from the ‘hot’ or ‘ground’ output connection) will produce a slightly different signal as physically they will be in different places), but averaged out over the pickup, the result will be the same. The only time there may be a very slight difference I know of would be on a early PAF-style pickups (exact copies) where thicker lead wires were joined to the winding wire, and some of the lead wire was wound around the bobbin, causing some disruption in the first layers of coil windings on one side of the pickup only, adding in a slight asymmetry to the signal if there were ‘forward’ and ‘reverse’ versions of the coil fitted in the same place. Later, the coil wires on humbuckers were joined to the lead wires outside the coil. On Fender single coils, the coil wire was always taken to the lead wire connection pads AFAIK.
Vintage P-90s may also have had a length of lead wire incorporated in the windings, as they came before PAFs and Gibson probably continued the same winding method used on the P-90, but at some point as production volumes increased, I expect they changed to externally connecting the lead wires on all pickups as it was quicker.
I doubt any Tonerider will have thicker lead wires that are wound on the bobbin, so for your pickups, there will be no measurable sonic difference.