I recently noticed that my jazzbass (cheap copy, passive) sounded weaker when using both pickups and stronger (and better) when using only one. I removed the pickguard and unscrewed the controls. I saw that the wires from each pickup are mounted in reverse. (neck PU : black wire to Vol pot 1 and white wire to ground / bridge PU : white wire to Vol pot 2 and black wire to ground) So the pickups are out of phase, right ? If so, is this normal (standard) for a jazzbass ? Do out of phase pickups have a hum-cancelling function ? (I can't really see another reason for it) Any help would be greatly appreciated, thanks.