What would happen if...

[big_teee]

That didn't sound too bad!
B_T

[Mark Hammer]

First, as much as I thought it was a dumb idea when I first started scrolling through this thread, I tip my hat to you for going through with it and putting it to empirical test. Good on ya, lad!

Second, the premise of differential sensing by each row of slugs suggests that inter-row spacing is at the heart of the matter. To whit, if the spacing between each row of slugs was, say, a 1/4", I don't think anyone would expect much. All of which begs the question as to whether you'd get more signal if the rows of slugs were spaced even farther apart than they are now. Of course, your current spacing is a fuinction of the size of the bar magnet, so you'd probably require some sort of magnetically conductive keeper for the polepieces to screw into, that would permit magnetic coupling over a wider distance, using the same bar magnet.

Of course, at that point, you'd be getting into something the size of an EBO bass pickup, which would obviously not fit in a standard size pickup route. And of course, whether it "works" is entirely separate from whether it sounds good or achieves anything different than what a conventional design already achieves.

I'm not dismissing it totally out of hand, but the "worth it" aspect remains to be determined.

I might note that the Dynasonic pickups with the adjustable polepiece require space between the coil and the polepiece on one side of the coil, so one of the notions that crops up is whether you get anything decent by using a bar magnet oriented top to bottom (rather than edge to edge), and removing or spacing one row of adjustable slugs.
Best of luck and happy winding.

[Possum]

I've done it and it does give you an out of phase sound because you have half the coil in one magnetic polarity and the other in the opposite. I still have it around here somewhere.....fun but useless...

[Plucky]

I hear gardening is not a bad hobby.

You owe me a new keyboard.

[Plucky]

Seriously, though, if you are determined to make this work, you could try using narrower bar mags, placing them on the outside of the polescrews with opposing fields: s><s or n><n. Adding a steel bar in the center with a high iron content might seal the deal, or it may mess it up, depending on what you are expecting.

I haven't given this response too much thought, but it might work. Perhaps Mike Sulzer and others could chime in on a more serious note...

[tonedeciple]

In the end, I'll probably put this pickup on the shelf next to my neo slug humbucker. Both were good tests of what is possible, though neither worked as well as I'd hoped. My next experiment will utilize the same bobbin shape I used for this dual polarity, single coil test. I think this bobbin may have some potential. It's the same footprint as a humbucker, but slightly taller. This will allow me to pack the bobbin with thicker wire (38 to 40 AWG). I'm also thinking of using two rows of Alnico V slugs with same polarity facing the strings. The goal is a more powerful single coil than a P90, but with thicker wire to help preserve clarity.

[CRU JONES]

Nice work Chris Thanks for sharing the pics and the sound samples! The prototype is very nice looking too.
Ethan

[Stealth]

Respectfully, Are You sure it didn't have 2 Bobbins.
T

Fairly sure, and I found the thread - it was on MEF/Pickups all along, and as I said it was similar, not the same - though I admit, now that I compare the threads, I might be off the mark quite a bit.
a single-coil pickup surrounded by polepieces. Though I'm not sure if the poles were all top-north and used the center as a return path.

[ken]

I tried this once because my wife asked me the same question... really.

The poles tend to cancel each other out, so the pickup doesn't really have enough magnetic field strength to work.

Result? A very weak, 'out of phase' sounding pickup.

ken

[J M Fahey]

This design is magnetically self cancelling.
The weak audio response achieved comes because the self cancellation is not perfect, and a little stray field still goes through the coil in a useful way.
There is no

the fact that one row will sense string vibration before the other.

effect.
Respectfully, saying so shows you donīt yet grasp how a magnetic pickup works.
Fact is, there is a magnetic path the magnetic field (or lines of force) follows, which includes a substantial path through air, a *terrible* magnetic field conductor.
The magnetic (steel) string which vibrates in it, varies its distance to the pole(s) so the effective path length varies following the musical sound.
Such magnetic modulation is turned into an audio voltage in the coil(s).
Itīs a closed path, thereīs no "one side getting it before the other" the same way that in a piece of wire connected to a battery there is no "current in one end starting before the other because itīs closer to the battery" or whatever.
Current along that path, in any point of the wire (or the battery) moves "all at the same time" once the circuit is closed, or stops "all at the same time" when itīs opened.
The exact same thing happens with the magnetic field here.

[Possum]

The one I made was actually a cool pickup in an odd way, I may actually revive it as a novelty pickup, mine wasn't weak at all, there is an easy solution, a bit awkward in construction but it worked great in neck position. If you have the poles equal heights you get maximum out of phase cancellation but if you disrupt it things change, making an endlessly tunable pickup. Still its not something except someone on acid would buy and is too time consuming to make. and making a bridge version with my prototype would be a bit difficult.