Potentially a very dumb question - Polarity switch?...

[tbassist4]

Is there any way to wire a switch to change the polarity of a pickup to turn humcanceling with another pickup on or off? Is this just as easy as reversing the leads or do you need to have pickups wired this way from the start?

Example:
Say you have a bass with three single coils, and can turn each one on or off by a switch. The neck and middle are RWRP - so they humcancel. The bridge however, can only humcancel with one or the other depending on how it is wound originally. Is there a way to throw a switch in there to reverse the polarity of the bridge pickup so that it can humcancel with either the neck or middle pickups?

[line6man]

You're talking about a phase switch, but the problem with phase inversion is that it applies to the entire output of the pickup- hum and signal.
Phase inversion causes destructive interference when combining the signals from two or more pickups, which gives you a thin, nasal tone.

[tbassist4]

Originally Posted by line6man

You're talking about a phase switch, but the problem with phase inversion is that it applies to the entire output of the pickup- hum and signal.
Phase inversion causes destructive interference when combining the signals from two or more pickups, which gives you a thin, nasal tone.

Ah I see, thanks for the response! So there's no other way to do what I want to do without having the pickups RWRP from the beginning?

[walterw]

right. for two coils to hum-cancel and sound right, both the coils and the magnets have to be opposite from each other.

[SGD Lutherie]

Originally Posted by tbassist4

Ah I see, thanks for the response! So there's no other way to do what I want to do without having the pickups RWRP from the beginning?

The issue is that if you just reverse the polarity, either by switching the (+) and (-) wires, or reverse winding the coil, then the two pickup are out-of-phase and sound very thin.

To make them sound back in phase while still canceling hum, you need to reverse the magnet polarity.

The problem with three pickups is you can only have hum canceling with two of them, so if they are South/North/South only the S/N pairs will hum cancel, but the two South pairs will not. There is no way to fix that situation with wiring.