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View Full Version : Reverse magnetic polarity in a pup?



tjcurtin1
December 21st, 2007, 01:27 PM
I was just putting away one of the pickups that I had used for a physics demonstration with my students when I realized that it had a reverse magnetic polarity from the other two pups it was stored with (two wanted to lie front to back, and this one wanted to lie back to back or front to front). They had all come out of my Fully strat - this was the middle pup. Is it this way on purpose, or does the magnetic polarity not matter in a set of pups? Just curious from the electrical/physics viewpoint.

tunghaichuan
December 21st, 2007, 01:38 PM
I was just putting away one of the pickups that I had used for a physics demonstration with my students when I realized that it had a reverse magnetic polarity from the other two pups it was stored with (two wanted to lie front to back, and this one wanted to lie back to back or front to front). They had all come out of my Fully strat - this was the middle pup. Is it this way on purpose, or does the magnetic polarity not matter in a set of pups? Just curious from the electrical/physics viewpoint.

This is how a standard humbucker is wired: two coils in series with magnets facing one polarity in one coil and the opposite polarity in the other coil. When the middle pickup is reverse polarity in a three-pickup strat set, the two "in between" positions on a 5-way switch, #s 2 & 4 are hum cancelling.

tung

tjcurtin1
December 21st, 2007, 04:17 PM
Cool, thanks Tung! So what is usually called 'reverse wound' is in fact reverse polarity I guess.

tunghaichuan
December 21st, 2007, 04:21 PM
Cool, thanks Tung! So what is usually called 'reverse wound' is in fact reverse polarity I guess.

I believe that they are two different things. Reverse wound means exactly that, the two coils are wound in opposition to each other. But they are still connected in series.

tung

marnold
December 21st, 2007, 05:26 PM
I believe that they are two different things. Reverse wound means exactly that, the two coils are wound in opposition to each other. But they are still connected in series.
Yes. Reverse wound is what Tung describes. Reverse polarity is that the pickup's magnets themselves are the opposite orientation of the other coil. If the two coils are reverse wound and reverse polarity (RWRP), they will buck hum, whether they are the two coils of a humbucker, the middle and neck or bridge of a Strat, or the two pickups on a Tele.

snarph
December 21st, 2007, 08:19 PM
some body must have installed the magnets flipped 180 degrees its not hard to do

Ascension
December 21st, 2007, 09:14 PM
some body must have installed the magnets flipped 180 degrees its not hard to do
Not on the single coils the middel will be RW/RP for the reasons allready stated to kill the 60 cycle humm.
Yep it's easy to do when swapping mags I just had to pull the Custom out of one of my USA Washburn MG's cause I stuck the new A8 mag in backwards. I put it back together fired it up and yep outta phase with the 59 in the neck :thwap: . As much as I have done this you would think I would know better :whatever: and yep I had the A8 mag clearly marked for polarity. I just GOOFED :whatever: :thwap: !

mrmudcat
December 22nd, 2007, 01:42 PM
Brother it happens to the best of us!!:master: :beer:

WTVintage
December 23rd, 2007, 10:12 PM
Reverse magnetic in a Pickup, It usually used in Single COIL pickups, when this term is used, is when they use pickups that their coil is in the reverse pole, so Hum is cancelled..

monradon
January 11th, 2008, 07:34 PM
you mean the middle pickup in a strat is wired different polarity ??

duhvoodooman
January 11th, 2008, 07:44 PM
Yup, at least in almost all the newer ones, for the S-S-S type. The middle pickup is both reverse polarity and reverse wound. This keeps it in phase with the other two pickups, but hum-cancelling when combined with either of the neck or the bridge pickups.