Pickup Mag Polarization

[boomerlu]

Does anybody know which way the magnets of pickups are polarized?

IE, bridge to nut, back of guitar face of guitar, or sideways?

Are strat magnetic pole pieces polarized differently?

I'm asking because I'm wondering if this has any influence on the single coil sound.

[Ben]

Back of guitar to front of guitar on a single coil, and bridge to nut on a humbucker.

EDIT:

*Generally. P90's have strange magnet layouts for example

Edited July 5, 2006 by Ben

[psw]

The magnetism needs to go through the core of the coil in the pickup. That is north or south running through it...not both. So, with a single coil the magnet is inside pointing towards the string through the core...or a magnet is attached below a steel core with one polarity up so that the steel becomes an extention of the magnet itself and directs it through the core.

On a humbucker, the magnet polerises one set of pole pieces in one coil north, the other coil south. There is a magnet between them, one side north and the other south so the whole together makes a kind of U shape with the magnetisim of opposite polarities being directed through each coil. This and reverse winding on one of the coils makes for the humbucking effect. Combinations of single coils can also achieve this effect if the magnet and winding is reversed (normally on the middle pickup) RWRP pickups.

Different magnet arrangements create different sensing magnetic shapes. A P90 for instance has two magnets both directing the same polarity through the steel core of a single coil. This magnetic shape and the wider coil contribute to the distinctive sound of the p90...the field produced though is the same...the same polarity through the core...

Hope that helps... pete

[JoeAArthur]

This isn't an answer and it will probably only add to the confusion.

On the first 15-20 years or so of Strats, the polarity of the pickups was the same and nobody complained. Then the middle pickup became RWRP to provide a humbucking effect in positions 2 and 4. Again, nobody complained.

With dual humbuckers, the traditional wisdom has been to turn them so that the two polarities facing each other in the middle are the same. The reasoning is that like poles repel each other and therefore this should prevent magnetic interference. Nobody complained.

However, as psw pointed out - the two coils of a humbucker have opposite polarities right next to each other, and there are guitars with one humbucking pickup - and again, nobody complains.

Now I haven't done any sort of scientific study on it, but to me that last case of opposite polarities right next to each other would be the worst case. If you think about it, the concentration of magnetic field would be at the top of the poles of each coil, in the field of the string vibration, but very little magnetic field would be going down to cut across the windings of either coil between the two coils. The magnetic field that does cut through the coil windings to produce the output voltage would be on either outside of the humbucker. This could suggest a reason why a split coil humbucker doesn't really sound like a single coil pickup.

But nobody complains. Bottom line, if nobody complains with all possible combination of polarities, then maybe the polarity relationship of adjacent pickups doesn't really matter - no matter what the theory.

[boomerlu]

The magnetism needs to go through the core of the coil in the pickup. That is north or south running through it...not both. So, with a single coil the magnet is inside pointing towards the string through the core...or a magnet is attached below a steel core with one polarity up so that the steel becomes an extention of the magnet itself and directs it through the core.

On a humbucker, the magnet polerises one set of pole pieces in one coil north, the other coil south. There is a magnet between them, one side north and the other south so the whole together makes a kind of U shape with the magnetisim of opposite polarities being directed through each coil. This and reverse winding on one of the coils makes for the humbucking effect. Combinations of single coils can also achieve this effect if the magnet and winding is reversed (normally on the middle pickup) RWRP pickups.

Different magnet arrangements create different sensing magnetic shapes. A P90 for instance has two magnets both directing the same polarity through the steel core of a single coil. This magnetic shape and the wider coil contribute to the distinctive sound of the p90...the field produced though is the same...the same polarity through the core...

Hope that helps... pete

Yes, this helps quite a bit.

And Joe...you pretty much hit the nail I was trying to get at!

See, here's the thing...

The lowest energy (and thus preferred) configuration of a dipole is IN LINE with the magnetic field lines. The premise of the pickup is that the magnet induces a dipole on the strings, and then when the string vibrates, it induces an EMF (Faraday's law).

SO...the polarization direction of the pole pieces of a humbucker would point in the same direction as the magnet. And the polarization direction of the strings would too. On the other hand, on most single coils the polarization is from the back of the guitar to the front. These configurations both produce different induced dipoles in the string, and therefore different fields. Thus, they should produce fundamentally different sounds, even if say the humbucker were split into a single coil...

That said, the coil split on my humbucker closely approximates the sound of a single coil (not dead on of course). It's got the bite, the top end. It's just a bit uglier, but that's because (I think) the pickup was designed to be a humbucker and not two single coils.

Joe, as you said: nobody complains!

Conclusion? The hype pickup manufacturers sell us is probably just hype. None of this actually matters that much. What really matters is the resonant frequency and the height of the peak, at least to the leading orders.

[SwedishLuthier]

If you are unterested in the magnetif field in pickups you should hava a look at Steven Kertins page www.skguitars.com He has FEMM simulations of magnetic field for a lot of different pickups. Those simulations really got me to understand A LOT more about WHY pickups sound like thay do.

[boomerlu]

If you are unterested in the magnetif field in pickups you should hava a look at Steven Kertins page www.skguitars.com He has FEMM simulations of magnetic field for a lot of different pickups. Those simulations really got me to understand A LOT more about WHY pickups sound like thay do.

I am very much interested, but from what I can tell the link is dead? I googled his name as well as SK Guitars, but nothing of note came up. Could you provide a working link?

Thanks

[SwedishLuthier]

I'm at work right now, so I cannot provide the URL right now. And I noticed that I had a type-o. His name is Steven Kersting. I know that he has some problems with his site from time to time, so this might be the case right now. If he doesn’t get the problem sorted out in a few days I might publish them myself. I got them saved at home, and I have Stevens word that I can use then for an article about pickup winding, so I might just write that article and publish that at my own site later on

Anyway, I will post a link tonight.

[boomerlu]

Ahh, the link is actually just

www.skguitar.com