Stack Pickup Patent Devers 6846981

[Scott S.]

Been reading some patents, and this one is very curious.

Its a stack strat/tele humbucker with seperate magnets for the upper and lower coils, and the north of the upper coil magnet is arranged toward the north of the lower coil.

One way to look at it is (I guess), take a side by side humbucker made with Fender rod magnets and move the one coil under the other.

Aren't the magnets going to demag each other, and/or what other effects on the magnetic circuit will occur?

Maybe I am dense, but I don't understand this one, the other patents I have checked out make sense to me. If this works why do all the big guys use magnetic shields?

[David Schwab]

I saw this one a while back.

The mags wont demagnetize each other because they are the same strength.

The idea behind this is with stacked pickups, if the magnets run though both coils, so North is on top and South is on the bottom, the two coils are enough out of phase that you get a thin tone.

So one way around this has been putting a magnetic shield between the coils, and using no magnets in the bottom coil. But this on the other hand can reduce the output of the pickup.

The DiMarzio Virtual Vintage pickups use a technique where the bottom coil has high inductance (it has extra steel slugs) and fewer turns of wire than the top coil, so it cancels less.

So I think the idea here is to have two active coils, but not magnetically opposite, and wound the same, and the way the magnets are they sort of shield one coil from the other.

This is the same way the Les Paul recording pickups were made, only they had a thick steel plate between the coils.