Different gauge wire on same pickup

[Brian W.]

For example half of the coil is 42g and the other half is 43g [ for the sake of the topic make it 3 K each gauge]. Any dramatic or noticeable affects in sonic properties compared to a pickup wound completely with one or the other gauge wire? If there are any obvious detriments to combining wire gauges I'd like to consider them before using up my wire. I remember some tapped pickups that use smaller gauge wire so looks like somebody is using it!

Thanx!

[copperheadroads]

These are topics you should find out for your self by winding .It's a wonderful learning experience .

[Antigua]

For example half of the coil is 42g and the other half is 43g [ for the sake of the topic make it 3 K each gauge]. Any dramatic or noticeable affects in sonic properties compared to a pickup wound completely with one or the other gauge wire? If there are any obvious detriments to combining wire gauges I'd like to consider them before using up my wire. I remember some tapped pickups that use smaller gauge wire so looks like somebody is using it!

Thanx!

Even though a pickup is more or less and inductor (hence the inductance is usually very high) , it's a "non ideal" inductor, which means it also has some parallel capacitance across the turns of wire (which is a small capacitance) and series resistance along the length of the copper wire (which is also rather small). The combination of those factors is also known as a resonant "RLC" circuit. The inductance "L" and the capacitance "C" resonate, giving the pickup a "resonant peak", while the series resistance "R" gives that resonant peak a particular Q factor (along with "eddy currents", but that's not related to the choice of wire).

When you decide between different types of wire, you're just changing around the non-ideal aspects of the inductor. If you dedice to use 43 AWG instead of 42 AWG, the resistance per foot is higher, so the "R" value of the RLC circuit goes up, and the Q factor goes down a little bit. When you choose a wire that has a thicker build of insulation, the capacitance "C" goes down, so the resonant frequency goes up a little bit. The type of coating, enamel or polysol, have slightly different dielectric values, which also slightly changes the capacitance. And of course when you add more turns of wire, the inductance "L" goes up, and L increases in greater proportion than does the capacitance or the resistance, since it's principally an inductor, while the so-called "real" resistance and the "parasitic" capacitance are just along for the ride.

If you have a Strat pickup wound to 6k ohms with 42 AWG, it comes out a bit over 7k ohms with 43 AWG, for a net gain of about 1k ohms series resistance, which decreases the Q factor at resonance by a very small amount, and that's the distilled answer to the original question. In my observations, the insulation thickness and/or material type can vary the capacitance in a Strat pickup by as much as 100pF, with 80pF being the floor, and a bit over 200pF being the ceiling. I feel comfortable in saying that there is no sonic difference as a result of adding or removing those amounts of capacitance or resistance, but some claim to perceive audible differences. The pickup's capacitance and Q factor are also dependent on the other components in the circuit, such as the control pots and the amp input impedance, so there might be particular circumstances where a small change in value is more noticeable, and times when it's not at all.

[Brian W.]

These are topics you should find out for your self by winding .It's a wonderful learning experience .

I'm aware of the learning experience...however I have a limited supply of magnet wire from which to gain my results. If there is, in fact [or theory ] a negligible difference in combining two gauges of wire on the same coil then I'm not going to waste time or wire on the process. If splicing two different wire gauges together has inherent negative influences on the overall sound of the pickup I would like to know in advance what I'm getting myself into.

[Brian W.]

Even though a pickup is more or less and inductor (hence the inductance is usually very high) , it's a "non ideal" inductor, which means it also has some parallel capacitance across the turns of wire (which is a small capacitance) and series resistance along the length of the copper wire (which is also rather small). The combination of those factors is also known as a resonant "RLC" circuit. The inductance "L" and the capacitance "C" resonate, giving the pickup a "resonant peak", while the series resistance "R" gives that resonant peak a particular Q factor (along with "eddy currents", but that's not related to the choice of wire).

When you decide between different types of wire, you're just changing around the non-ideal aspects of the inductor. If you dedice to use 43 AWG instead of 42 AWG, the resistance per foot is higher, so the "R" value of the RLC circuit goes up, and the Q factor goes down a little bit. When you choose a wire that has a thicker build of insulation, the capacitance "C" goes down, so the resonant frequency goes up a little bit. The type of coating, enamel or polysol, have slightly different dielectric values, which also slightly changes the capacitance. And of course when you add more turns of wire, the inductance "L" goes up, and L increases in greater proportion than does the capacitance or the resistance, since it's principally an inductor, while the so-called "real" resistance and the "parasitic" capacitance are just along for the ride.

If you have a Strat pickup wound to 6k ohms with 42 AWG, it comes out a bit over 7k ohms with 43 AWG, for a net gain of about 1k ohms series resistance, which decreases the Q factor at resonance by a very small amount, and that's the distilled answer to the original question. In my observations, the insulation thickness and/or material type can vary the capacitance in a Strat pickup by as much as 100pF, with 80pF being the floor, and a bit over 200pF being the ceiling. I feel comfortable in saying that there is no sonic difference as a result of adding or removing those amounts of capacitance or resistance, but some claim to perceive audible differences. The pickup's capacitance and Q factor are also dependent on the other components in the circuit, such as the control pots and the amp input impedance, so there might be particular circumstances where a small change in value is more noticeable, and times when it's not at all.

Thanx for reminding me about the insulation. I also forgot that the wire itself can vary in thickness from spool to spool. There also is the actual "sound" of the guitar itself [neck & body] which interacts with the pickup. Not all pickups get the desired affect from all guitars. I prefer to match up the individual pickup with the instrument in order to enhance the qualities of the sound. I'm thinking that combining wire gauges may just be an intellectual exercise that won't really yield solid audible results.

[Mike Sulzer]

For example half of the coil is 42g and the other half is 43g [ for the sake of the topic make it 3 K each gauge]. Any dramatic or noticeable affects in sonic properties compared to a pickup wound completely with one or the other gauge wire? If there are any obvious detriments to combining wire gauges I'd like to consider them before using up my wire. I remember some tapped pickups that use smaller gauge wire so looks like somebody is using it!

Thanx!

This is a very interesting question. One of the things that makes electronics fun and practical is that the behavior of three simple theoretical devices, Rs, Ls, and Cs, actually describes very well real manufactured devices over their intended frequency ranges. And when it does not, you can make the models better by adding one or two more of these theoretical devices to the model of the manufactured device. You cannot be sure that this is always true, and I suspect that this might not work so well for a guitar pickup under unusual conditions.

For example, I am working on a pickup design, a sidewinder, in which each coil has 4000 turns of #42 and 3000 turns of #44 on top of that. The individual sub coils behave as expected but the series combination has higher than expected capacitance. Maybe I am measuring wrong or not allowing for some obvious effect. However, based on this experience, (at least until I understand what is happening) I would not put different size wires on a coil if I was just trying to make a normal pickup.

[Antigua]

Thanx for reminding me about the insulation. I also forgot that the wire itself can vary in thickness from spool to spool. There also is the actual "sound" of the guitar itself [neck & body] which interacts with the pickup.

The difference in series resistance due to min/nom/max differences in the wire would be a lot less than the difference between 42 and 43 AWG. As Mike said, that would impact the Q if there was no other loss to consider, but the eddy currents in the pole pieces and the control pots bring the Q factor down so far that a few hundred ohms plus or minus is highly trivial.

[Antigua]

For example, I am working on a pickup design, a sidewinder, in which each coil has 4000 turns of #42 and 3000 turns of #44 on top of that. The individual sub coils behave as expected but the series combination has higher than expected capacitance. .

A picture is worth a thousand words in these cases; maybe the coils capacitively couple with a metal base plate, maybe it's the hookup wire, or maybe the orientation of the coils. If you dismantle the pickup, does the capacitance change?

Another case where the physical capacitance was a lot higher than modelling would suggest was when I tapped an SSL-5, the capacitance jumped from 143pF to 444pF, nearly a three fold increase, even though the portion of coil that remained in series was halved.

[Brian W.]

This is a very interesting question. One of the things that makes electronics fun and practical is that the behavior of three simple theoretical devices, Rs, Ls, and Cs, actually describes very well real manufactured devices over their intended frequency ranges. And when it does not, you can make the models better by adding one or two more of these theoretical devices to the model of the manufactured device. You cannot be sure that this is always true, and I suspect that this might not work so well for a guitar pickup under unusual conditions.

For example, I am working on a pickup design, a sidewinder, in which each coil has 4000 turns of #42 and 3000 turns of #44 on top of that. The individual sub coils behave as expected but the series combination has higher than expected capacitance. Maybe I am measuring wrong or not allowing for some obvious effect. However, based on this experience, (at least until I understand what is happening) I would not put different size wires on a coil if I was just trying to make a normal pickup.

HHmmm.....wonder what it would sound like!

[Helmholtz]

The individual sub coils behave as expected but the series combination has higher than expected capacitance.

Could you verify that the unexpected effect depends on wire gauge?

Did you consider coupling and reflected capacitance?

[Mike Sulzer]

A picture is worth a thousand words in these cases; maybe the coils capacitively couple with a metal base plate, maybe it's the hookup wire, or maybe the orientation of the coils. If you dismantle the pickup, does the capacitance change?

Another case where the physical capacitance was a lot higher than modelling would suggest was when I tapped an SSL-5, the capacitance jumped from 143pF to 444pF, nearly a three fold increase, even though the portion of coil that remained in series was halved.

no baseplate; no significant leads. Just an early prototype.

Yes, I have seen the effect that you described on tapped coils. It is much reduced if you break the connection to the part that is "hanging". That is, you really need multipole switching.

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.

[Mike Sulzer]

HHmmm.....wonder what it would sound like!

Well, as you can guess, I am attempting a dual mode pickup. Something like a tele bridge resonance frequency and single coil sampling, but much more output, no hum, and higher Q if you want it, with a much higher inductance lower Q mode with higher output for use with high overload. But this is not so easy. I would like to understand a bit more before putting it in a guitar.

[Mike Sulzer]

Could you verify that the unexpected effect depends on wire gauge?

Did you consider coupling and reflected capacitance?

I have not really verified that, but have never seen this with a single wire size. Perhaps you need to consider all of that and more.

[Brian W.]

Well, as you can guess, I am attempting a dual mode pickup. Something like a tele bridge resonance frequency and single coil sampling, but much more output, no hum, and higher Q if you want it, with a much higher inductance lower Q mode with higher output for use with high overload. But this is not so easy. I would like to understand a bit more before putting it in a guitar.

My brain pan becomes imprinted with images like this.......................

[Antigua]

My brain pan becomes imprinted with images like this....................... [ATTACH=CONFIG]58489[/ATTACH]

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.