Capacitance of braided shielded wire (Gibson type), if you please? :-)

[Mike Sulzer]

EXACTLY.

Conservation of energy applies because you don't "boost" things in a passive circuit with passive components. You can trade current for voltage or the other way around, but you'll always have losses when you do that, passive or active. Nothing is 100% efficient, and definitely nothing is MORE than 100% efficient.

You can trade away current to get more voltage; that is how a microphone transformer increases the voltage delivered to the grid of a tube (a very high impedance), 10 to maybe 20 times. The transformer has some (small) losses, but it still increases the voltage. So does a guitar pickup. Have I measured this? Of course. Go right ahead, try it. Wind a pickup with a very a high natural resonance. Make a test setup with an exciting coil. Add a C to move the peak to 5 KHz. See that the voltage is now greater than at low frequencies, where there is very little loss, or at 5KHz with the capacitor removed.

[Mike Sulzer]

Let's look at why what I wrote is true for a guitar pickup. Connect a voltage source V at fequency f across a series LC circuit resonant at f. For the moment assume that they are both have very low loss, so you have a large Q. The same current flows through both elements; voltage lags current for the C, leads it for the L, degrees, both not quite 90 degrees because of the small losses. Wait a while for the transient response to settle. The voltage across the L and C are nearly 180 degrees out of phase which means that they must be large, much larger than V since they must add (out of phase) to give V. Now put some resistance across the C; the voltage drops, but it is still larger than V as long as the resistor is large enough. This is the situation with a guitar pickup operating into a high impedance load.

[Joe Gwinn]

EXACTLY.

Conservation of energy applies because you don't "boost" things in a passive circuit with passive components. You can trade current for voltage or the other way around, but you'll always have losses when you do that, passive or active. Nothing is 100% efficient, and definitely nothing is MORE than 100% efficient.

Well, you're both right and you're both wrong. Or, more sharply, a pox on both your houses.

It is energy that is conserved, not voltage. A transformer can raise the voltage, but the current will necessarily be reduced, such that their product is constant (ignoring the usually small losses in the transformer).

The physiology of hearing is more important than conservation of energy or the location of the resonance. If one attenuates the lows, the result will sound sharper. If one attenuates the highs, the midrange will grow by comparison. If one attenuates the midrange, the result will sound hollow.

[Mike Sulzer]

You are saying what I was saying about the current-voltage relationship; I said nothing wrong; why are you claiming I did? If you really think I said something wrong, please identify it. Also, you did not address the main issue, whether the resonant peak of a pickup actually boosts the voltage over what it would be without the resonance. It you are going to tell me I am wrong, at least address the issue and identify the problem with what I am saying.

I really do not appreciate you putting a curse on me. All I did was correct erroneous statements; I expect an apology.

Well, you're both right and you're both wrong. Or, more sharply, a pox on both your houses.

It is energy that is conserved, not voltage. A transformer can raise the voltage, but the current will necessarily be reduced, such that their product is constant (ignoring the usually small losses in the transformer).

The physiology of hearing is more important than conservation of energy or the location of the resonance. If one attenuates the lows, the result will sound sharper. If one attenuates the highs, the midrange will grow by comparison. If one attenuates the midrange, the result will sound hollow.

[wizard333]

So for the non-irretrievably stupid, here's the deal:

Gibson braided (usual install with the wires bundled/soldered together just before selector switch: Measured cap hot-shield ~89pf. Also, there is stray capacitance all through this; measured cap hot-hot on any 2 of the 3 (1 from each pickup to switch plus return) = ~80-100pf.

Allparts 4 conductor wire: Actually higher, cap conductor to conductor and to ground ~100-120pf.

Doesn't sound like much in isolation, but the aural affect of all the stray capacitance between the conductors and ground makes a huge impact on the sound of the instrument. Some people may like the high end reduction, but it also kills pick attack and articulation, so if you pick fast, this is anathema. I'd suggest if you like high end roll off, do what I did below and then use a small cap across your output (easily removed) or on a tone control. I'd suggest .001uf on your tone control to approximate it.

Re-wired with George L cable (yes it fits): Measured cap per wire: 21pf, so for either pickup to and from the switch, about 42pf. More importantly, from any conductor to any other, capacitance was NOT MEASURABLE. No stray capacitance causing phasing, high end loss, other issues.

Aural result: MASSIVE improvement in clarity and touch sensitivity. Pickups sound like they should, guitar responds electronically as it does acoustically. Problem solved.

[Mike Sulzer]

I'd suggest if you like high end roll off, do what I did below and then use a small cap across your output (easily removed) or on a tone control. I'd suggest .001uf on your tone control to approximate it.

Right, so if you can put the effect back in by adding a cap across the output, then you could have removed it with less trouble by using a cable a few feet shorter. No need to rewire the guitar. Why are you suggesting the use of a 1000 pf cap to replace the effect of 100 or 200 pf, approximately?

I assume that you have done some serious analysis and now understand how the pickup resonant circuit boosts the voltage at the resonance above the low frequency value.

[wizard333]

I suggest you re-read the 1st line of the post. The post was not for you. Kindly leave the teching to those of us who can figure things out and make them work. Thx.

[freefrog]

Doesn't sound like much in isolation, but the aural affect of all the stray capacitance between the conductors and ground makes a huge impact on the sound of the instrument.

I agree.

Some people may like the high end reduction, but it also kills pick attack and articulation, so if you pick fast, this is anathema.

We've already discussed this question above.

I'd suggest if you like high end roll off, do what I did below and then use a small cap across your output (easily removed) or on a tone control. I'd suggest .001uf on your tone control to approximate it.

FWIW, that's the value recommended in Seymour Duncan's FAQ 10 or 15 years ago. EDIT: bad reading. The value mentioned in the old FAQ was 100 or 150pf (= the capacitance of 1m of standard guitar cable).

Re-wired with George L cable (yes it fits): Measured cap per wire: 21pf, so for either pickup to and from the switch, about 42pf. More importantly, from any conductor to any other, capacitance was NOT MEASURABLE. No stray capacitance causing phasing, high end loss, other issues.

Aural result: MASSIVE improvement in clarity and touch sensitivity. Pickups sound like they should, guitar responds electronically as it does acoustically. Problem solved.

IME, low cap wiring improves the sound when the pickups used have a high inner stray capacitance, suffer from Eddie currents and/or have a very high inductance. It becomes unnecessary if not counterproductive if the pickups themselves are clear sounding by design.

IOW, YMMV and this variation doesn't appear to be a question of irretrievable stupidity - LOL.

[Mike Sulzer]

I suggest you re-read the 1st line of the post. The post was not for you. Kindly leave the teching to those of us who can figure things out and make them work. Thx.

This is a public forum; you can send private messages if you want. Otherwise you have no control over who responds. Your posts contain errors; no reason not to correct them.

[salvarsan]

How does the internal wiring's capacitance compare to that introduced by the guitar cable to the amp?
Hanging 10 feet of something ranging 20-50pf/ft off the guitar may be more significant.

[Mike Sulzer]

I suggest you re-read the 1st line of the post. The post was not for you. Kindly leave the teching to those of us who can figure things out and make them work. Thx.

Oh, and I forgot to post this link: Resonant filters : Filters. It discusses resonant filters made with Rs, Ls, and, Cs. It discusses a case similar to the resonant filter that a guitar pickup is. You might be interested in this statement: "The output voltage to the load at this point actually exceeds the input (source) voltage!". Apologies if the material in this link is too difficult for you. It was the simplest I could find.

[Mike Sulzer]

How does the internal wiring's capacitance compare to that introduced by the guitar cable to the amp?
Hanging 10 feet of something ranging 20-50pf/ft off the guitar may be more significant.

Sure is.

[salvarsan]

in response to significance of cable capacitance: Sure is.

I think more wicked fun may be had with disingenuously innocent rhetorical questions than with derision and spleen.

Must be gettin' old.

"You kids! Git offa da lawn!"

[JGundry]

I don't know where you guys get your braided cable but I can tell you there is zero capacitance difference between the braided Gibson style cable I order in large spools and the cable in my vintage '52 and '56 Les Paul's. There is no there, there.

[Mike Sulzer]

I think wizard333 has rewired the guitar with special low capacitance cable, the kind with very thin center conductor and larger than normal outer diameter. It is a lot easier to change the guitar cable, shorter and/or low cap cable, and you can get even more change. Of course he is also eliminating the small coupling between pickups at very high frequencies. I do not think that this is a significant effect, and in any case, Gibson would probably argue that this coupling is a feature, not a bug, and that you should not try to modify the sound of these instruments.