Different gauge wire on same pickup

[Brian W.]

Those look like active effects, which is sort of like putting your pedal board in a new cavity of the guitar. One of the things I love about guitar electronics is seeing how far the limits can be pushed with passive components, and in the case of pickups, figuring out how to get the most from the least.

Yup, they are effects. All I initially saw were "switches" !
There were some BC Rich guitars that had nearly that number of switches on them [not for effects] .

I have a Strat that I installed a Clapton Mid Boost / Pre-amp circuit in. Very versatile quitar...but...... I still prefer just volume / tone knobs.

[mozz]

5 various spools of Litz wire for experiments, which i will get to in about 8 years from now. I know 1 has 7 conductor, another has 20.

[Joe Gwinn]

[This capacitive thing is complicated. Even a simple air core single layer rf coil is hard to do. I think the most successful way uses a transmission line model. I recall that Joe Gwinn might know more about this. But when you consider a coil with many layers and high permeability cores, it is a real mess.

The transmission-line dodge was how to measure the thickness of the insulation on magnet wire. Roll two meters up into a ball and immerse is concentrated salt water held in a stainless steel container of some kind. Keep the ends of the waire oput of the salt water. Using a LCR meter, measure capacitance between steel container and the copper core of the magnet wire. Knowing the kind of insulating varnish used and its dielectric constant (will be in the wire datasheet), compute the dielectric thickness.

For something as geometrically complicated as a pickup with core, there is no simple equation, and one normally uses numerical approximations. The best approach is to obtain qualitative rules tying coil shape to both inductance and self capacitance. I published the numerical approach some years ago. Search for my name and capacitance and perhaps energy. (I couldn't find it right now.)

[Antigua]

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This capacitive thing is complicated. Even a simple air core single layer rf coil is hard to do. I think the most successful way uses a transmission line model. I recall that Joe Gwinn might know more about this. But when you consider a coil with many layers and high permeability cores, it is a real mess.

The complexity mostly seems to be an issue when you have two coils close together, and their spacial relation somehow adds or takes away depending on various factors, such as whether the coils are coaxial, or side by side, and so on. But for a given coil, I've not observed so much mystery, the taller thinner (Strat, Tele neck) coils uniformly have higher capacitance than short wide coils (Jazzmaster) which makes perfect sense, if you consider that the start of and end of the coils are physically farther apart with the thin coil. A couple years ago I brought a URL to your attention, someone's blog, where they argue that if magnetic coupling follows with the axis, then the capacitive coupling must be perpendicular to the axis, I don't know if that's true, but a wider coil does produce more overall wire-to-wire distance perpendicular to the axis, which supports, or at least doesn't disprove that assertion. If that were true, a single layer coil should have almost no capacitance, since there would be no neighboring wire perpendicular to the axis, and I dont know if thats the case, but I'm sure someone does.

Within the lumped capacitance there can be anomalies, which are seen in the bode plots extending up to 100kHz and beyond, where smaller high frequency resonances and seem to be more present the more unevenly the coil is wound (building up on one side, then building up the other), where it seems that small resonances form within the coil, across small sections of the coil. I think that's fundamentally similar to that second resonance that is seen with humbuckers, where the splitting of the coil into two halves cause each to resonate on its own in addition to a resonance of the whole.

[Slight Return]

I make a tapped coil pickup starting with 42 and ending with 43.

FWIW: The capacitance of the tap is 224pF, and the full coil is 160pF. Made another and it measured 189pF for the tap, and 121pF for the full coil.

Found it interesting that the capacitance is lower for the "full coil" but for the tap position with a lower readout, the capacitance is higher.

As for tone? In my experience, the difference is negligible. I've used 38 or 39AWG on very tall bobbins and heard no difference when using the same turn count as 42 AWG.

The main reason I use both gauges in the tapped coil is "6.0k" is much easier for people to relate to, and understand as a "classic" Strat sound, than 7.5k or whatever it would come out to with 43. Even though I doubt they would sound different.

Plus, it also divvies up my wire usage so I'm not burning through either my 43 or 42 wire too quickly.

Turn count is the big factor. Thinner wire can be used to save space or cram more turns onto a bobbin than you'd normally be able to. Outside of that I just stick with plain old 42.

I've also tried pickups with Formvar and Plain Enamel done to the same turn count as the poly coated wire I normally use, and could not hear a difference. So for me, insulation thickness is also not really an important variable.

If you're trying to save money, IMO, it isn't worth your time to experiment. Some people need to do it for themselves and come to their own conclusions. I'm not gonna tell anyone else that they're wrong or that different wire or insulation thicknesses make no difference. But for me, I can't hear any difference, and am more than happy to stick with 42 single build poly wire.

[Antigua]

I make a tapped coil pickup starting with 42 and ending with 43.

FWIW: The capacitance of the tap is 224pF, and the full coil is 160pF. Made another and it measured 189pF for the tap, and 121pF for the full coil.

Found it interesting that the capacitance is lower for the "full coil" but for the tap position with a lower readout, the capacitance is higher.

It is interesting, but it's also telling; capacitors in parallel increase overall C, while capacitors in series decrease overall C. If the tapped capacitance is higher, it must mean that a more of the capacitance has become parallel. It makes sense when you think about it.

I've also tried pickups with Formvar and Plain Enamel done to the same turn count as the poly coated wire I normally use, and could not hear a difference. So for me, insulation thickness is also not really an important variable.

I think the dielectric constant for both is in that are of 3 to 4. I've measured a lot of pickups wound with both and have never seen that the capacitance ever varies by any obvious amount.

Here's a fun thing to do, just to see it happen with your own eyes, soak an unpotted Fender style pickup in water, and then measure the capacitance while it's water logged. It will dry out on it's own, and the capacitance measurement will tell you that it has fully dried, too.