Flipping or Spinning a Magnet....

[Runewalker]

on a single coil with that bar of ceramic magnet.

Has anyone ever UN-glued one, spun it and reglued it to change the polarity?

If so how did you un-glue it, and what kind of adhesive did your use to re-glue it.

Did it work to convert to reverse polarity?

RW

[wolf]

I did this with a P-90 pickup with alnico magnets that were epoxied to the pickup "plate" (or whatever the heck that thing is called). (P-90's have 2 magnets).
Having a feeling that alnico might be fragile, I pried the magnets loose with a guitar pick. It probably took me 15 minutes for each magnet. But I was successful.

Incidentally, a pickup's magnet is NOT polarized like those grade school magnets you probably remember where NORTH was at one end and SOUTH was on the other.

A pickup magnet is polarized along its edges. (I tried making drawings but visiting my website would probably be a better idea:
www.1728.com/guitar1a.htm

Just thought I'd mention this because if you flip a pickup magnet about its vertical axis the polarity doesn't change. You have to flip it about its horizontal axis. Why is a pickup magnet polarized in such a strange fashion? If it had that "grade school" polarity, there would be a sharp decrease in volume around the D & G strings.

As Pee Wee Herman once said "it's one of those things they don't teach you in school. You have to find it out for yourself". And that's true for me because I only noticed this stuff as I took pickups apart. Even on the Internet this information is not exactly strewn all over the place. (Does the pickup industry like to keep secrets?)

[ChrisK]

It makes sense for the magnetic poles on a P-90 magnet to be along the wide edges since we want a relatively consistent field thru each pole piece. The same holds for most other pickup types.

I don't have a clue about a lipstick tube pickup's topology. I'll have to measure the magnetic field on the one that I have.

If one end was north and the other south, there would be a signal phase reversal as compared from one end to the other (assuming a constant winding method) once the magnet is reversed.

If you flip the magnetic polarity, you also have to reverse the connections of the pickup wires to the guitar circuit for equivalent signal phasing.

I don't know about adhesives, but I'd avoid any between the magnet and the pole pieces.

[UnklMickey]

chrisk said:

...I don't have a clue about a lipstick tube pickup's topology. ....

Chris,

from what i've heard, the magnet in a lipstick is where the pole-pieces in a strat pup are.

the coil is wound around it.

so to make one of those "RWRP", all one need do is flip the entire innards over.

string sensing is still normal, but in relation to external EMF, it's now reversed.



unk

[ChrisK]

Yeah, this makes perfect sense. I'd got my magnet polarity detector out, but forgotten why (of all of the things that I've lost, I miss my mind the most).

Not only are you reversing the magnetic polarity, you're also reversing the wiring direction, so all is indeed RWRP.

[Ripper]

So when Fender says reverse wound pups, what is it that theyre doing?

[JohnH]

Deepblue - what I think most RWRP are, for a basic single coil, is that the coil is physically the same as non RWRP (actually wound the same way as any other), but the coil connections to the leads are reversed and the magnets are flipped. Reversing the coil connections reverses the phase of the hum and the signal. Reversing the magnets reverses the signal but not the hum. So the signal gets reversed twice, and ends up unchanged and in-phase with other pups. But the hum is reversed once, and is then out of phase with that of the other pups, for hum cancelling combinations.

John