# Reversing a pickup's polarity. Fun with magnets.



## fraser (Feb 24, 2007)

the set of pickups i put in my latest strat all shared the same polarity, so i couldnt get hum cancelling in the 2nd and 4th positions. not a big deal, but since its just a spare set of pickups, and i had free time, i did some experiments.
before i continue- all you guys who already now about this, or you pickup winders, or any fancy buggers who somehow know everything there is to know about magnets, feel free to laugh and make fun of my fumblings. i dont care.
im a "guitar enthusiast", not a pickup maker.

anyways, i took apart a hard drive and took out its magnets-










then, i oriented them in my vice, so that the 2 magnets were in "attract" mode- meaning the sides facing each other wanted to stick, not repel.
because they are magnets they cling nicely to the vice and stay in place.
like so










i got an old pickup out of my junk box and used my compass to determine its polarity-










so its south. i want to see if i can reverse the polarity to north-


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## fraser (Feb 24, 2007)

i take the pickup and slide it between the magnets on the vice- making sure not to make contact with the magnets.
going several times in the same direction i pass it through.



















as it turned out, i was holding the pickup the wrong way around- checking with the compass showed that i had accomplished nothing. flipping the pickup the opposite way, so the staggered side of the polepieces faced the other way, i tried it, and it worked.










i played around with flipping the pickup around a bunch of times, reversing the polarity back and forth to ensure it was a satisfactory result each time- and it always was.
so i threw the middle pup from my strat in there, and reversed its polarity. then i wired it back in, with the wires reversed to simulate a reverse winding. and its now hum cancelling in the 2 and 4 positions. completely- just like a stock set with rwrp middle pickup.

however, i found i hadnt passed the pickup through the magnetic field enough- as its output was now lower- checking with a screwdriver, the polepieces on that pup where less magnetic than the other 2 in the guitar. but it sounded great!
i simply pulled it back out, and passed it slowly about 20 times through the vice again, and the magnets strengthened. but from this ive also learned that i can affect the strength of the magnets, to manipulate the tone somewhat- maybe sweeten up some otherwise harsh pickups or something. ill mess with that another time.
anyway, maybe this will be of use to somebody someday!


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## AlterEgo (Jan 12, 2010)

Interesting experiment ... thanks for sharing.


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## greco (Jul 15, 2007)

Cool...very interesting. 

I hope Jon Moore comments.

Thanks for taking the time to post the pics and write up the process, findings, etc.

Dave


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## jimihendrix (Jun 27, 2009)

way to go fraser...you just broke the laws of nature...you might have disrupted the space/time continuum...


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## gtrguy (Jul 6, 2006)

Doesn't reversing the magnetic polarity without reversing the wind direction mean that pickup's output is now out of phase with the others?


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## lbrown1 (Mar 22, 2007)

this is cool - I spent years in electronics school....all sorts of time screwing around with electric motors n' such - and never once had it occurred to me that the polarity of a magnet can just be switched like that

thanks for sharing


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## fraser (Feb 24, 2007)

jimihendrix said:


> way to go fraser...you just broke the laws of nature...you might have disrupted the space/time continuum...


well, the sun came up at the right time and place in the sky today- so i guess its all good!



gtrguy said:


> Doesn't reversing the magnetic polarity without reversing the wind direction mean that pickup's output is now out of phase with the others?


exactly- thats the idea-
putting the pickup at a reverse polarity puts it out of phase with the others- then i wired it backwards- swapping the leads from where theyd normally connect.
so the pickup is out of phase in two ways from the others. 
so when combined with the other two pickups- positions 2 and 4 on the 5 way switch- its hum cancelling.
lots of strat pickup sets, if not most these days, have a reverse wound, reverse polarity pickup in the middle to do this- 
all ive done here is take a set of three pickups that were all the same winding and polarity, and changed one to reverse wound, reverse polarity- its not actually reverse wound of course, but swapping the leads accomplishes the same thing.
the middle pickup on its own functions exactly as it did originally, cant be out of phase with itself- 
this all works on the same principal as a single humbucker with 2 coils- but the idea here is to do the same using 2 seperate coils, as in two single coil pups.



> this is cool - I spent years in electronics school....all sorts of time screwing around with electric motors n' such - and never once had it occurred to me that the polarity of a magnet can just be switched like that
> 
> thanks for sharing


i was aware that i could degauss a pickup using magnets, but didnt realize i could charge them that way too-
it was looking at these-
STEWMAC.COM : Guitar Repair Magnets

and seeing how they are used to charge the polepeices here-
STEWMAC.COM : Single-coil Pickup Kits Free information

that it came together-
those stew mac magnets are neodymium boride- and so are the ones in an old hard drive. i had no way of knowing if the hard drive magnets were as strong as the stew mac ones
and if they would do the job- but i figured if this experiment failed, id spend the pocket change and get a set of the stew mac ones.
i had a few old hard drives here anyway- we use the magnets at work to pull splinters out of ourselves lol.
the idea was to degauss the pickup, then regauss it at the opposite polarity-
but i found it isnt necessary to think that much-
simply passing the pickup through the magnetic field, then checking its polarity will tell you wether youve got it oriented correctly or not- if not you merely flip the pickup around.


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## mhammer (Nov 30, 2007)

I did the same thing a couple months back with some smaller 3/4" diameter neodymium magnets from Lee Valley and can confirm that it works like a charm.


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## fraser (Feb 24, 2007)

mhammer said:


> I did the same thing a couple months back with some smaller 3/4" diameter neodymium magnets from Lee Valley and can confirm that it works like a charm.


excellent mark- did you have a similar experience with the strength of the magnets bieng affected by the amount of time spent in the field?


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## mhammer (Nov 30, 2007)

I actually didn't fritter around quite that much, and quite frankly it doesn't take much exposure to do the deed.

Some 23 years ago, I visited the former Evans pickup "facility" just outside Victoria to pick up some polepieces. They scooped up a handful and magnetized them for me on the spot. It took all of about 3 seconds, and they're still good and strong decades later.


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## J S Moore (Feb 18, 2006)

You have to be careful sometimes with the grade of Alnico you try that with. I think rod magnets are isotropic so it doesn't matter what orientation they have but the Alnico 5 I have in bar stock is anisotropic. It will only orient one way. A2,3 and 4 are isotropic and Alnico 5 is cast in a magnetic field which makes it anisotropic. You can magnetize it the other way but it's very weak.

I do pay attention to gauss levels and generally don't gauss magnets to their full strength. I just don't find they sound very pleasant that way. Single coils particularly. And there is a generally lower gauss to vintage magnets than modern.


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## fraser (Feb 24, 2007)

mhammer said:


> I actually didn't fritter around quite that much, and quite frankly it doesn't take much exposure to do the deed.
> 
> Some 23 years ago, I visited the former Evans pickup "facility" just outside Victoria to pick up some polepieces. They scooped up a handful and magnetized them for me on the spot. It took all of about 3 seconds, and they're still good and strong decades later.





J S Moore said:


> You have to be careful sometimes with the grade of Alnico you try that with. I think rod magnets are isotropic so it doesn't matter what orientation they have but the Alnico 5 I have in bar stock is anisotropic. It will only orient one way. A2,3 and 4 are isotropic and Alnico 5 is cast in a magnetic field which makes it anisotropic. You can magnetize it the other way but it's very weak.
> 
> I do pay attention to gauss levels and generally don't gauss magnets to their full strength. I just don't find they sound very pleasant that way. Single coils particularly. And there is a generally lower gauss to vintage magnets than modern.


yup, i just have no idea what these pickups really are- they are cheap, they are alnico- but thats it.
to get the one i switched polarity on to match the strength of the other 2- or up to its original strength, it took about 20 slow passes.
wether this is due to the rod in the pickups, the magnets im using to charge them, or my method, i do not know.
one thing is for sure- these pickups are cheap- and they sound it. 
before i upped the strength on that middle pickup it sounded much better. smoother with less of the odd spiky frequencies cheap strat pups display.
fwiw- these pups show a resistance of 5.6, are relatively low output, and set very low in the pickguard.
in any case, im just messing around, learning stuff and experimenting while ive got time.
thanks for replying guys!


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