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2 Quick Questions


Ben
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p90andsc0gw.jpg

Just 2 quick questions:

  1. Is the arrangement of the magnets on the left correct for a P-90? (the block in the centre is steel)
  2. Could this arrangement with these 2 pickups be used to create a humbucking effect ? (Coils are wound in same direction- I'll flip the wires on one)
I'm pretty sure that the answers to both of these questions is yes, but I just want to make 100% sure before I start winding anything.

I thought I saw the P-90 magnet layout somewhere before, but I cant seem to find it any more to confirm.

I know the humbucking effect might not be perfect since the coils are a little mis-matched, but I'm not too bothered. Also it may look like it will sound like mud with the two in series, but I've thought about that. :D

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Cool, I'd heard reports that wiring P-90s like a humbucker just made it sound like mud.

I'm doing lots of experimenting with the wiring on this guitar, and one of the things I'm doing will allow me to vary the resistance of the pickup, so if it does sound too muddy I could decreace the resistance a bit and brighten it up a little.

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Does reversing the wires = reverse-winding, though? My brain won't wrap around the magnetics of it all, but if it were that simple, why would they bother making "reverse-wound" pickups for the purposes of humbucking?

Greg

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the p-90 is a single coil forgive me if im wrong but the arrangment on the left appears to have two coils :D . if the sound was too fat you could just change the eq but this doesnt appear to be a problem from what Godin SD said

in response to your question greg, you may often see the abreviation rw/rp when it comes to single coils, this means not only is the p/u reverse wound but also reverse polarity (the magnet that is)

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Does reversing the wires = reverse-winding, though? My brain won't wrap around the magnetics of it all, but if it were that simple, why would they bother making "reverse-wound" pickups for the purposes of humbucking?

I thought it wouldnt, but I think somebody at the MIMForum told me it did once... thats what I'm a little uncertain about...

the p-90 is a single coil forgive me if im wrong but the arrangment on the left appears to have two coils wink.gif

The diagram has one coil (or at least its meant to look like it does :D)

Its meant to show a coil of copper wire wrapped around the steel core in the centre. I *think* I saw the magnets arranged like that on Jason Lollar's site once, but the diagram doesnt seem to be there anymore...so maybe it was another site.

I just want to confirm that this is OK before I go wind anything.

Edited by Ben
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My understanding is that with 2 similar pickups (can't speak to 2 completely different types), if you have the same polarity but reversed wiring on one, you'll put yourself out of phase, even if the hum is bucked.

Greg

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ah i see now but it still looks to me as though you have two magnets, below is an interpretation of your digram with (if there is only ment to be) one magent with the south polarity in the centre

__

____l l ___

l l l l

l l l l

l l l l

N S S N

it would make more scence to me if it looked like

____l l ___

l l l l

l l l l

l l l l

N _ S

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My understanding is that with 2 similar pickups (can't speak to 2 completely different types), if you have the same polarity but reversed wiring on one, you'll put yourself out of phase, even if the hum is bucked.

Seems to make sense... but bear in mind that the magnetic polarity on one is S and the other is N... I *think* that that means that they'll induce opposite voltages (out of phase voltages) , so wiring them out of phase will be like doubly out of phase = in phase.

Kudos to you if you can make sense of that :D

Its hard to try to explain something that I dont fully understand.

George- the diagram is supposed to have 2 magnets- I think thats how P-90s are amde (but im not completely sure, thats something I'm trying to confirm)

I'm presuming that the 2 souths in the centre give the pickup an 'overall' south polarity.

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Greg's right - you can't just reverse the wires, because the signal will be out of phase - however, you can rotate either the magnet (if possible) or the whole pickup 180º (so the wires come out the other side) and reverse the wires, and it will work correctly. Ibanez used this trick on some of their guitars, apparently to avoid the cost of winding a special pickup.

Edited by lovekraft
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however, you can rotate either the magnet (if possible)

In the diagram the magnet is rotated (i think)...

I was meaning reverse the wires with the magnets set up as in the pic

I was presuming that the p-90 would have a S polarity overall because the S poles on the magnets are closest to the steel core- (I may be wrong about that though)

To make this easier for me to understand, which of the combinations below will work:

(1) each pickup has opposite magnetic polarity, both wound in same direction, wires on 1 pickup reversed

(2) pickups have same magnetic polarity, one is reverse wound, wires on one pickup reversed

(3) each pickup has opposite magnetic polarity, one is reverse wound, wires on one pickup reversed

The diagram was meant to illustrate (1)

I could set it up as in (2) or (3) without too much trouble though.

Would the P-90 in the diagrams overall magnetic polarity be S, or am I incorrect in assuming that?

Thanks for the help so far :D

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OK, I lied... make it 3 quick questions :D

Can you pot a pickup in CA? obviously I'd make sure it worked before I did something irreversible like that, but the thin stuff seems penetrating enough to soak into the whole coil, and it seems a lot simpler than wax.

Also I found this:

http://www.1728.com/guitar1a.htm

most interestingly it says that "it is not necessary to have the coils physically wired in opposite directions."

Does that mean arrangement (1) above would actually work, and that arrangement (3) would also work if the wires werent reversed...?

I hope thats right, I think I'm starting to get my head around this :D

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Great!- thats cleared that up then, thanks Setch.

Coincidentally I've read your post just as I was returning to this topic to post this:

http://www.lollarguitars.com/BobbinDesigns/p90_bobbin.jpg

I KNEW it was from jason lollars site!

The reason I couldnt find it before is that since he's updated his site its not accessible anymore.

I found it through google image search.

(http://images.google.co.uk/images?q=p90+pickup&svnum=10&hl=en&lr=&client=firefox-a&rls=org.mozilla:en-US:official_s&start=20&sa=N)

Looks like that magnet arrangement is right for a P-90 then!

The only thing that I'm still not sure of is if the P-90 in my diagram would be equivalent to a pickup like the one to the right with the S pole facing upwards...

It'd probably be easier to just make both pickups have the same design, but I like the sound of P-90s.

And of course theres question about CA that I just posted.

Thanks

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There’s a lot involved in getting the pickups humbucking. When the two signals is mixed the hum is cancelled (plus and minus hum equals zero hum, kinda). If one pickup produces a stronger signal than the other the hum picked up will be stronger and not all hum will be cancelled.

To do this you need to do two things:

-You need to get different magnet poles “pointed” against the strings and

-you need to have the coil reversed. If so, the induced hum will be electrical out of phase.

In the drawing of your P90 the resulting upwards magnetic pole is south and the SC is north so you’re fine with that. If you wound one of the pickups reversed you will get at least some hum cancelling. Mind you, P90 traditionally have much higher output. A P90 is often wound to 10 Kohms and a SC to everything between 7 and 9 Kohms*. That will mean that you will at least get partial hum cancellation.

Regarding reverse winding, Jason Lollar described it pretty good in his book. You actually don’t need to WIND the coil reverse. You only need to have a “reversed path to ground”. That means that if you wind two coils in the same way, you can connect the starting lead of the first coil to the ground, and the end lead of the second to ground. If they have different magnetic polarity they will be humbucking if combined.

*The believe that the output of a pickup is dictated by the DC resistance is actually a misunderstanding. It is the number of windings and the magnetic field strength that produce the electric current that is later amplified. BUT DC resistance is a good indicator of the difference between pickups of the same model. But if you compare a P90 to a Tele neck, one turn or wire around a P90 will be considerable longer and have a higher resistance. Never the less it is only one turn of wire. And will produce (if all other factors are constant) the same current as one turn of wire around the Tele neck pickup

Ben, if you are concerned about the two pickups sounding muddy in series, try parallel. That will also be humbucking but with a much more open, singe-coilish sound

I have tried CA for potting. It’s messy and you will get a rock solid coil that’s not going to be able to “peal” but it works fine.

I have one guitar with a P90 and a standard SC (in fact it is part of my avatar…) and it works fine. Both pickups balance each other fine.

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Many thanks, SwedishLuthier!

That clears up everything I was unsure about...

Mind you, P90 traditionally have much higher output. A P90 is often wound to 10 Kohms and a SC to everything between 7 and 9 Kohms*.

I was just going to wind them equally and hope that the increased amplitude of the vibrating strings in the neck position would compensate for the stronger magnetic field in the P-90

I'm not too concerned about getting perfect 100% hum cancellation

But if you compare a P90 to a Tele neck, one turn or wire around a P90 will be considerable longer and have a higher resistance. Never the less it is only one turn of wire. And will produce (if all other factors are constant) the same current as one turn of wire around the Tele neck pickup

Dont tele neck pickups use thinner wire?.. I think its 43 AWG.

I understand what you are saying though.

Ben, if you are concerned about the two pickups sounding muddy in series, try parallel.

I'm going to :D

Theyre going to be wired to a 5way switch, using a schematic called '5 sounds from 1 humbucker' - thats why I need to make sure that they are arranged in the same way as a humbucker would be; to ensure that they will work with the schematic.

I think the 5 sounds are neck coil single, bridge single, both in series, both in parralel, and both out of phase.

The only thing I'm not sure of is this:

not going to be able to “peal”

Because I'm not sure what peal means :D I thought it was something a bell did...

Anyway, thanks very much, that answers everything.

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Dont tele neck pickups use thinner wire?.. I think its 43 AWG.

Jup. That is to be able to wind enough turns on a bobbin that leave you with less space for the wire compared to the Tele bridge pup or a Strat SC.

The thinner wire also affects the tone , but that is not the topic here…

The only thing I'm not sure of is this:

not going to be able to “peal”

Because I'm not sure what peal means :D I thought it was something a bell did...

Pardon my French.. or Swedish or whatever. I meant peel. Kind of a funny type-o when we are talking about pickups and possible microphonics…

To peel a pickup is to unwind (or actually most often just cut away with an exato-knife) the wire so that the pickup can be rewired.

I saw your winder thread. Nice to see that more people are picking up on winding. Good luck with the pickups.

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Pardon my French.. or Swedish or whatever. I meant peel. Kind of a funny type-o when we are talking about pickups and possible microphonics…

To peel a pickup is to unwind (or actually most often just cut away with an exato-knife) the wire so that the pickup can be rewired.

Haha- the microphonic feedback thing was my best guess at what you meant.

If the pickups dont work I'll just salvage the magnets and make a new bobbin instead of trying to rewind.

I saw your winder thread. Nice to see that more people are picking up on winding. Good luck with the pickups.

I'm working on winder mkII right now as a matter of fact :D

Thanks

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