Pickup winding question

[Mike Sulzer]

Remember that permanent magnetism has nothing to do with canceling hum. Coils that match in sensitivity to magnetic fields, but connected in opposite phase, do that.

The function of the permanent field is to magnetize the string.

The field inside a rod magnet is somewhat stronger in the middle. The poles are significant because that is where a strong field is accessible.

Yes. That's how most stacked pickups are made.

Keep in mind that the magnets have the poles on the ends, and are null in the middle.

[David Schwab]

Remember that permanent magnetism has nothing to do with canceling hum. Coils that match in sensitivity to magnetic fields, but connected in opposite phase, do that.

The function of the permanent field is to magnetize the string.

The field inside a rod magnet is somewhat stronger in the middle. The poles are significant because that is where a strong field is accessible.

Right, but I was pointing out that on a rod magnet you have opposite poles at the ends where the coils are on a stack. Just to point out why it works at all and you don't have total phase cancelation of the strings.

[Mike Sulzer]

The reason that it works is this:

The vibrating magnetized string makes a fluctuating magnetic field. The pole piece is immersed in this field and modifies it (if it has a high permeability), tending to reduce the spreading out of the field lines; that is, stop the field from getting weaker. But it still does get weaker. Thus, the bottom coil sees a weaker field and so the signals do not cancel.

It has nothing to do with the north and south magnetic poles.

Right, but I was pointing out that on a rod magnet you have opposite poles at the ends where the coils are on a stack. Just to point out why it works at all and you don't have total phase cancelation of the strings.