Can someone explain to me exactly what humbucking pickups do (i.e., musicman) as opposed to a J-bass pickup? can a MM pickup be wired for passive (as an extra pickup on a P-bass?) in place of the traditional P/J setup? also, where is a good place to find wiring diagrams to put stuff like this together? Sorry so many questions, I want to put together a bass and have no experience in this area.