Can a stacked single coil be parallel to self?

[zionstrat]

I have never used the lower coil of a stacked single coil for anything other than noise canceling. I've always assumed that it's far enough away from the strings that it would not generate much signal.

But an EE friend of mine looks at this a different way. Because each coil is tied up in a complex flux pattern, he believes the lower coil sees a significant signal and, if I understand him correctly, he has used them in parallel to self mods.

I would be interested in your experience if you have used the lower coil for anything other than noise canceling.

And now that I've written this, I very well may could be missing something. I've always imagined that the parallel sound comes from mixing of two coils that have similar output but I might be wrong about that as well.

[freefrog]

It depends on the architecture of the noiseless pickups involved.

First gen noiseless stacks had extra long rod magnets travelling through the upper and lower coils as shown for instance in this old patent by Willi Lorenz Stich, a.k.a Bill Lawrence:

https://patents.google.com/patent/US3902394A/en

Then designers started to limit the rod magnets to the upper coil, as shown in some figures of these DiMarzio patents:

https://patents.google.com/patent/US4442749A/en?oq=us+patent+4%2c442%2c749

https://patents.google.com/patent/US5811710A/en?oq=us+patent+5811710

Then noise sensing coils started to be wound with the same number of turns but thicker wire as explained in this Kinman patent:

https://patents.google.com/patent/GB2311160A/en?q=patent&assignee=christopher+kinman&oq=us+patent+christopher+kinman

It's really not a limitative list patent wise but it should already illustrate what I'll try to share: the idea that obviously, the "tonal weight" of the noise sensing coil is not the same with these various models and their further developments.

If I take for example an old design stack for Telecaster that I've recently repaired: coils were measuring respectively 5.25k / 5.09k and the related inductance (2.07H and 1.8H respectively). Both in parallel would measure 2.58k and 0.96H (vs 10.34k in series for an inductance of 2.23H only, for reasons explained somewhere in the patent above). 0.96H is extremely low (as low as with a Strat SC sized TriSonic) but still useable and not so far from the inductance in series so the tonal gap wouldn't / shouldn't be that huge..

If we consider now a first gen Kinman Impersonator 54, with a signal coil @ 6.41k and the noise sensor @ 1.07k, the overall DCR will be of 1k once both coils in parallel and the inductance of 0.73H approximatively, vs 2.8H in series. And as the noise sensor is magnetically isolated from the signal coil (albeit it has a robust inductance relatively to its DCR because of the ferrous content of its inert slugs), it should really lower the overall output level in a non useable way once wired in parallel with the upper coil...

I'll stop there before to fall in apparent pettyness but you'll get the idea: measure the DCR and inductance of both coils in a stacked pickup then look how far its magnetic poles go through the coils. It should tell if the PU promises to be playable in parallel or not - although the best way to know remains to try it, of course. So my rambling might be useless finally. :-P

HTH, nevertheless. :-)

[freefrog]

I can't EDIT my answer above for some reason so I'll correct one of my sentences here:

The old design Tele stack that I was evoking measured "0.34k in series for an inductance of 2.23H only, for reasons explained somewhere in the patentS [plural] above".
These reasons being in the fact that coils are out of phase for noiseless operation. Wired in series and in phase in the same old gen Tele noiseless stack, they would measure 10.34k and an inductance of 5.43H (because of "mutual inductance") with the related noise - in the P90 range. :-P

Oh, and I've forgotten to add that inductance might / should be even lower than the 0.96H or 0.73H stated in my answer, precisely because coils are OOP (in the same way than the measured inductance of a regular HB drops if its coils are in series but not in phase).

[zionstrat]

Thanks Freefrog! As usual, there's more to the equation than my black and white, plumbing based thinking. You gave me lots to dig into which I always love. Much appreciated, Michael

[Mikelamury]

It depends on the architecture of the noiseless pickups involved.

First gen noiseless stacks had extra long rod magnets travelling through the upper and lower coils as shown for instance in this old patent by Willi Lorenz Stich, a.k.a Bill Lawrence:

https://patents.google.com/patent/US3902394A/en

Then designers started to limit the rod magnets to the upper coil, as shown in some figures of these DiMarzio patents:

https://patents.google.com/patent/US4442749A/en?oq=us+patent+4%2c442%2c749

https://patents.google.com/patent/US5811710A/en?oq=us+patent+5811710

Then noise sensing coils started to be wound with the same number of turns but thicker wire as explained in this Kinman patent:

https://patents.google.com/patent/GB2311160A/en?q=patent&assignee=christopher+kinman&oq=us+patent+christopher+kinman

It's really not a limitative list patent wise but it should already illustrate what I'll try to share: the idea that obviously, the "tonal weight" of the noise sensing coil is not the same with these various models and their further developments.

If I take for example an old design stack for Telecaster that I've recently repaired: coils were measuring respectively 5.25k / 5.09k and the related inductance (2.07H and 1.8H respectively). Both in parallel would measure 2.58k and 0.96H (vs 10.34k in series for an inductance of 2.23H only, for reasons explained somewhere in the patent above). 0.96H is extremely low (as low as with a Strat SC sized TriSonic) but still useable and not so far from the inductance in series so the tonal gap wouldn't / shouldn't be that huge..

If we consider now a first gen Kinman Impersonator 54, with a signal coil @ 6.41k and the noise sensor @ 1.07k, the overall DCR will be of 1k once both coils in parallel and the inductance of 0.73H approximatively, vs 2.8H in series. And as the noise sensor is magnetically isolated from the signal coil (albeit it has a robust inductance relatively to its DCR because of the ferrous content of its inert slugs), it should really lower the overall output level in a non useable way once wired in parallel with the upper coil...

I'll stop there before to fall in apparent pettyness but you'll get the idea: measure the DCR and inductance of both coils in a stacked pickup then look how far its magnetic poles go through the coils. It should tell if the PU promises to be playable in parallel or not - although the best way to know remains to try it, of course. So my rambling might be useless finally. :-P

HTH, nevertheless. :-)

That was very informative and interesting. Thanks for posting that. I always appreciate learning new things and the way you explained that with the examples was very easy to understand.