String based current induced pickup shared idea

[Antigua]

With it being summer, I won't be able to personally try this out for a while.

So if the idea is that the B field is constant, and the string moves, then the timbre is dictated by where along the length of the string the B is most dense, so if the magnet is placed where the neck pickup would be, the B field is most dense there, and those characteristic "neck pickup" harmonics would be represented in the voltage output. Since the magnet is polar, it would have the same behavior as a standard magnetic pickup, where movement towards and away from the magnet's face constitutes most of the voltage, and movement across the magnet's face would produce little voltage.

If you need a long magnet to get a sufficiently strong voltage, that could be a problem, because it would cancel out narrow width harmonics. On the other hand, it opens the possibility of having many little magnets far apart.

Also, wouldn't the noise level be quite high? The magnetic fields of external noise would be very large, emanating from distant sources, while the intentional B field of a magnet would be relatively small, so what electromagnetic noise might lack in amplitude it would make up for in area. The entire string, or the entire loop, would be acting as a large antenna. It could be humbucking though, if it were designed so that half of the strings were wired out of phase with the other half.

[Mike Sulzer]

With it being summer, I won't be able to personally try this out for a while.

So if the idea is that the B field is constant, and the string moves, then the timbre is dictated by where along the length of the string the B is most dense, so if the magnet is placed where the neck pickup would be, the B field is most dense there, and those characteristic "neck pickup" harmonics would be represented in the voltage output. Since the magnet is polar, it would have the same behavior as a standard magnetic pickup, where movement towards and away from the magnet's face constitutes most of the voltage, and movement across the magnet's face would produce little voltage.

If you need a long magnet to get a sufficiently strong voltage, that could be a problem, because it would cancel out narrow width harmonics. On the other hand, it opens the possibility of having many little magnets far apart.

Also, wouldn't the noise level be quite high? The magnetic fields of external noise would be very large, emanating from distant sources, while the intentional B field of a magnet would be relatively small, so what electromagnetic noise might lack in amplitude it would make up for in area. The entire string, or the entire loop, would be acting as a large antenna. It could be humbucking though, if it were designed so that half of the strings were wired out of phase with the other half.

With only one turn instead of thousands it might not be bad at all.

[Helmholtz]

With only one turn instead of thousands it might not be bad at all.

Maybe, but it's about S/N.
Loop area is easily maybe 20 times larger and signal EMF might be some hundred times lower.
I don't expect much benefit compared to standard single coils regarding noise.

[Antigua]

I've been giving thought to practical application, because I like pickup theory but I'm also pragmatic. In an solid body electric context, one drawback would be the inability to change the sound magnet's positioning with the flick of the toggle, the magnet would have to be moved in order to alter the timbre.

Given the fact that it wouldn't need permeable steel strings to work, it might have application with an acoustic guitar, although there are already some very slim magnetic pickups for acoustic guitars, small enough that they can hide at the heel end of the fingerboard, by the sound hole, and from what I gather, it might require a neodymium magnet in order to get a sufficient B field in a similarly small area. And of course it would compete with piezo pickups, though it would sound distinctly different from a piezo. The low to hi Z transformer(s) would instantly put the cost higher than a piezo, and probably higher than a typical magnetic pickup. One thing I'm unclear on is whether each string needs its own transformer, or if one can server all six strings.

I would drop everything and test this out, but with the nice weather and kids out of school it will be a little while, and since it's hard to ponder a practical application, it's mostly for the sake of itself.

[bbsailor]

Maybe, but it's about S/N.
Loop area is easily maybe 20 times larger and signal EMF might be some hundred times lower.
I don't expect much benefit compared to standard single coils regarding noise.

The hum test that I initially tried was to hold the body, not the tip, of a active soldering gun near the strings. Yes, there was induced hum from the strong current in the soldering gun body. Then, I thought how humbucker pickups neutralize the hum with signal phases. I then changed the input phase of each alternate string into the transformer input and the hum was reduced. The best noise reduction came when alternate strings are about the same diameter.

This is just one more experiment that MEF members can do to try out this new pickup concept.

Thanks

Joseph J. Rogowski