The capacitive coupling of various guitar parts

[ms]

Apr 16, 2017 20:17:52 GMT -5 Charlie Honkmeister said:

Apr 16, 2017 13:42:10 GMT -5 ms said:

In all the cases relevant here (coax, twisted pair, two parallel wires, one wire over ground plane)  the capacitance per unit length is not dependent directly on spacing, but rather on the inverse of the logarithm of a ratio.  The ratio is spacing to wire radius, where spacing has the relevant interpretation for each case.  It also depends directly on the dielectric constant of the insulator. There are two consequences:

1.  You can not change  by huge amounts because the log function varies slowly with change in the ratio.
2. If low capacitance is your goal, using small wire is just as important as large spacing.

For rf coax cables, the goal is a characteristic impedance allowing efficient transmission.  This characteristic impedance is the square root of inductance per unit length divided by capacitance per unit length.  Very low capacitance is not required.  Coax cable designed for low loss usually has an impedance of 50 ohms.

Thanks, Mike,  believe you are correct on all counts.  But I did want to give a very general idea of what is involved here.  Introducing characteristic impedance of a transmission line, dielectric constants, etc. wouldn't make a lot of sense to the non-EE or non-physics crowd.  

Generally guitar wiring  (including the center conductor of most cables)  is in the AWG 18-24 range and the absolute difference in radius of the conductors of wires in that range  I wouldn't think would matter very much (not even close to an order of magnitude difference per unit length), especially since most wire is insulated and the insulation is on the same order of thickness as the wire itself,  limiting the minimum distance possible between conductors.    

If you have a link to a formula reference for this effect, it would be great to share for those who want to chase this down in more detail using real data for insulated wire specs.  

-Charlie

What you want to do is make spacing large and wire radius small if you want low capacitances.  The pickup is about a mile of wire, you can use as small a wire as is mechanically practical for hookup without affecting the performance relative to the resistance of the pickup.  Low capacitance audio cable uses small inner conductor, large outer conductor and low dielectric constant insulator.  You need to do all three since the log is such a slow function.

[antigua]

Apr 16, 2017 9:56:02 GMT -5 Charlie Honkmeister said:

Apr 16, 2017 1:30:02 GMT -5 antigua said:

   

The four conductor is higher capacitance, but it's only about a foot, which is not as bad as having it the whole length of a guitar cable.

It's more interesting than that, though. Suppose you have the humbucker wired in series, you have two of those wires tied off at the other end of the cable. The signal is between the two coils, and subject to that capacitance, so you effectively have a capacitor to ground in between the two pickups, creating a tiny secondary resonance. It's so small, and of a high frequency, that you can't hear it, but you can see it in bode plots. 

Four conductor shielded pickup cables have quite a bit of capacitance to ground.   It isn't normally a big issue since in most cases,  the cable capacitance is the largest value and mostly determines how far the pickup resonant frequency shifts down.  20-60 pF won't matter much in resonant frequency when you are using a 15 to 20 foot cable with anywhere between 650 pF and 1200 pF capacitance.  

Just FYI,  if one were to minimize pickup wiring capacitance,  twisted pairs or just unshielded wires (as in some Bill Lawrence pickups) would work in a shielded control cavity. 

Just as a reminder,  capacitance is inversely proportional to the square (or cube, don't remember which)  of the distance between the conductors.   So shielded cables which have a relatively large distance between any center conductors and the shield foil or braid,  inherently will have less capacitance.  You can see that in RF coax cables, such as RG-59U,  where high capacitance would mean unacceptable loss of signal at high (RF) frequencies.

Because of the distance effect,  if you wanted to gild the lily on low capacitance,  all signal wiring should be run in the center space of a shielded control cavity and as much as possible not run next to the "walls"  or back cover.    Since the capacitance drops off very quickly starting at fairly small distances between conductors,  you won't buy yourself much reduction in capacitance that way.  But sometimes neat, centralized, bundled wiring with not much excess in the control cavity,  can make a small difference, especially with certain styles of clean playing. 

If you lose high end definition before the pickup signal even gets to the amp,  just turning up the treble doesn't always work to get the sound you like for clean playing.  

I'm having to deal with this myself because I'm doing electrically variable capacitance for pickup voicing.   If the inductance of the pickup is relatively  high,  I have to go to really low capacitance values to get a good resonant frequency range and be able to get the resonant frequency as high as I want for hi-fi or Fender/Gretsch tone from the pickup.    Then stray capacitance in the wiring can be an  issue, even with a buffer to eliminate the effect of the cable and amp capacitance. 

I had performed a test with a wire and some foil here guitarnuts2.proboards.com/post/78778/thread and it looks like you'd get about 10pF difference from proximity between bare leads and the shielded cavity. That might make a difference if you have an on board active tone shaping as you do, but in a standard passive set up, it's a drop in the bucket. 

[Charlie Honkmeister]

Apr 17, 2017 13:53:27 GMT -5 antigua said:

Apr 16, 2017 9:56:02 GMT -5 Charlie Honkmeister said:

I had performed a test with a wire and some foil here guitarnuts2.proboards.com/post/78778/thread and it looks like you'd get about 10pF difference from proximity between bare leads and the shielded cavity. That might make a difference if you have an on board active tone shaping as you do, but in a standard passive set up, it's a drop in the bucket. 

The pickups I'm using are about in the 1.0 to 1.2 Henry range with a self-resonance of about 10 Khz at the end of the shielded cable.  That's deliberate overkill for approximately an 8 Khz maximum resonant frequency when everything is connected, including a possible gain mismatch (not exactly 1) on the buffer so the capacitance isn't completely cancelled out at maximum pot sweep,  so I'm allowing for some extra capacitance that way.

Generally I see anywhere from 150 to 250 pF , all pickup coil wires shorted together and capacitance measured from that point to ground,  from the commercial pickups I've tested.   Bill Lawrence L-90's are the exception with about 90 pF (no shielded cable, just 5 separate insulated wires from the pickup.) So about 10-20 pF from the pickup switch and maybe a bit of additional wiring to the buffer board isn't much of a problem. 

If I were shooting for 20+ KHz resonant frequency,  the pickup inductance would have to be about 550 to 650 milliHenries,  stray capacitance would be a lot more critical,  and the pickup output would be about 6 dB less,  so we would be looking at about a 12 dB preamp to bring the signal back up.   But 8-10 Khz maximum works very well for getting variable resonant frequencies from  1.2 to 5+ Khz to cover most classic tonalities we know and love.  

[pablogilberto]

Hi antigua!

Based on your experiment, placing the copper wires near some shielding (aluminum/copper foil) increases its capacitance.

Does this also mean that shielding a guitar cavity and pickguard (let's say a strat) also increases the overall capacitance.
Have you performed experiment on this?

I have read some claims from different people on the internet which claims that shielding a guitar will lead to some treble loss.
I'm thinking that the possible cause is the added capacitance due to shielding.

What do you think?


Thanks! 

[antigua]

Dec 28, 2019 21:01:13 GMT -5 pablogilberto said:

Hi antigua !

Based on your experiment, placing the copper wires near some shielding (aluminum/copper foil) increases its capacitance.

Does this also mean that shielding a guitar cavity and pickguard (let's say a strat) also increases the overall capacitance.
Have you performed experiment on this?

I have read some claims from different people on the internet which claims that shielding a guitar will lead to some treble loss.
I'm thinking that the possible cause is the added capacitance due to shielding.

What do you think?


Thanks! 

Shielding cavities doesn't increase capacitance because the shielding is far away from the wires, and the capacitance is proportionate to distance. Even if the wire were touching the shielding, the electrical field is only attracting along one side of the wire, where as shielded wire surrounds the conductor on all sides, so the potential for increased capacitance from shielding is probably less than 5pF, a very trivial amount.  I think the idea that shielding leads to treble loss is not true, I don't see potential for how it could be true. If you but a DE-5000 LCR meter for ~$100, these experiments are east to DIY with a piece of aluminum foil and some hookup wire.

That being said, I don't think shielding is very effective, because the pickups are the primary source of the noise. I think along with the myth that shielding reduces high end, it's probably also a myth that shielding reduces noise by any appreciable amount. So many control cavities and pickups have no shielding at all, and nobody seems to know whether they're shielded or not until they peak in the cavity and look, and I think that's telling. 

[pablogilberto]

Dec 29, 2019 2:46:50 GMT -5 antigua said:

Dec 28, 2019 21:01:13 GMT -5 pablogilberto said:

Hi antigua !

Based on your experiment, placing the copper wires near some shielding (aluminum/copper foil) increases its capacitance.

Does this also mean that shielding a guitar cavity and pickguard (let's say a strat) also increases the overall capacitance.
Have you performed experiment on this?

I have read some claims from different people on the internet which claims that shielding a guitar will lead to some treble loss.
I'm thinking that the possible cause is the added capacitance due to shielding.

What do you think?


Thanks! 

Shielding cavities doesn't increase capacitance because the shielding is far away from the wires, and the capacitance is proportionate to distance. Even if the wire were touching the shielding, the electrical field is only attracting along one side of the wire, where as shielded wire surrounds the conductor on all sides, so the potential for increased capacitance from shielding is probably less than 5pF, a very trivial amount.  I think the idea that shielding leads to treble loss is not true, I don't see potential for how it could be true. If you but a DE-5000 LCR meter for ~$100, these experiments are east to DIY with a piece of aluminum foil and some hookup wire.

That being said, I don't think shielding is very effective, because the pickups are the primary source of the noise. I think along with the myth that shielding reduces high end, it's probably also a myth that shielding reduces noise by any appreciable amount. So many control cavities and pickups have no shielding at all, and nobody seems to know whether they're shielded or not until they peak in the cavity and look, and I think that's telling. 

Thanks for answering. Big help.

If the pickups are the primary source of the noise, why don't we shield them instead?
Will shielding affect their tone?

From this article, guitarnuts2.proboards.com/page/gn1-qtb
It says that noise from fluorescent lights are often pickup from the controls rather than the pickup.
Is this correct?
I'm now confused.

Can you share any technical article/post regarding guitar noise and shielding so I can fully grasp them?

Thank you!

[antigua]

Dec 29, 2019 9:42:54 GMT -5 pablogilberto said:

Dec 29, 2019 2:46:50 GMT -5 antigua said:

Shielding cavities doesn't increase capacitance because the shielding is far away from the wires, and the capacitance is proportionate to distance. Even if the wire were touching the shielding, the electrical field is only attracting along one side of the wire, where as shielded wire surrounds the conductor on all sides, so the potential for increased capacitance from shielding is probably less than 5pF, a very trivial amount.  I think the idea that shielding leads to treble loss is not true, I don't see potential for how it could be true. If you but a DE-5000 LCR meter for ~$100, these experiments are east to DIY with a piece of aluminum foil and some hookup wire.

That being said, I don't think shielding is very effective, because the pickups are the primary source of the noise. I think along with the myth that shielding reduces high end, it's probably also a myth that shielding reduces noise by any appreciable amount. So many control cavities and pickups have no shielding at all, and nobody seems to know whether they're shielded or not until they peak in the cavity and look, and I think that's telling. 

Thanks for answering. Big help.

If the pickups are the primary source of the noise, why don't we shield them instead?
Will shielding affect their tone?

From this article, guitarnuts2.proboards.com/page/gn1-qtb
It says that noise from fluorescent lights are often pickup from the controls rather than the pickup.
Is this correct?
I'm now confused.

Can you share any technical article/post regarding guitar noise and shielding so I can fully grasp them?

Thank you!

There are two types of noise, electrical fields and magnetic fields. Faraday cages and shielding only block electrical radiation. Humbucking pickups only cancel out magnetic radiation. Empirically, most noise comes from magnetic fields, because when most people want a quieter guitar, their first choice is to get humbucking pickups. That is certain to reduce noise. Shielding on the other hand, is only ever described as being helpful, and people can't even agree as to how effective it is. Some pickups, such as humbuckers, Tele neck pickups or P-90's are shielded, and then not shielded, and you never see people say that the pickup is so much noisier after having removed the shielding. I've never once noticed it myself, nor have I seen anyone else mention more noise.

Some of the function of shielding is made moot if you plug into a well made guitar amp, because high frequency noise can enter the circuit via the guitar, and then become audible within the circuitry of the guitar amp, but most amps these days have an input filter or other circuit design considerations that prevent parasitic oscillations. I think shielding comes about as a matter of best practices, but shielding the guitar cavity of even the pickup itself barely makes any difference.

I might be able to do some testing, the trick would be to figure out what does or doesn't count as representative noise. It's possible that some environments have more electrical noise and less magnetic noise, or vice versa. 

[newey]

It's possible that some environments have more electrical noise and less magnetic noise, or vice versa.

This is a point that has been made many times over the years in this forum, and why shielding is often considered a "best practice". It may not make a difference most of the time, but there's always the possibility your gig will be in some bar with dodgy fluorescent light ballasts or ancient neon beer signs. Since one is already in the guitar rewiring it anyway, why not shield it? It's easy enough to do.

If the pickups are the primary source of the noise, why don't we shield them instead?
Will shielding affect their tone?

They are indeed the primary source, which is why, if one is going to shield, shield the pickup cavity first and foremost. Shielding the control cavity will probably never change the noise floor.

My search-fu is faltering today, and I can't locate the relevant thread, but back near the beginning of the board, one member did some fairly extensive testing of shielding the pickups themselves. The upshot of his research was that it did reduce noise somewhat, but that it affected the tone fairly severely, muddying things up.

However, he found that shielding the coil only about 3/4 of the way around minimized the treble losses while still providing some reduction in noise. At least, that's what I recall of it, from 11 years ago or so ago (so maybe don't trust my memory, hopefully one of the other oldsters can pinpoint the thread in question.)

We also have some research on shielding, done by former staffer D2o. It could perhaps be done more rigorously, but it is not a topic that has been ignored around here. John Astley's original Guitarnuts site, which spawned this community, was a paean to shielding from the start.

D2o's bit of research included a look at shielding, but the genesis of his research was a contentious issue here back in the day, the infamous "Urthman Controversy". D2o's testing was primarily aimed at testing Urthman's contentions.

guitarnuts2.proboards.com/thread/3375/benefit-get-shielding

[antigua]

Dec 29, 2019 11:16:08 GMT -5 newey said:

My search-fu is faltering today, and I can't locate the relevant thread, but back near the beginning of the board, one member did some fairly extensive testing of shielding the pickups themselves. The upshot of his research was that it did reduce noise somewhat, but that it affected the tone fairly severely, muddying things up.

However, he found that shielding the coil only about 3/4 of the way around minimized the treble losses while still providing some reduction in noise. At least, that's what I recall of it, from 11 years ago or so ago (so maybe don't trust my memory, hopefully one of the other oldsters can pinpoint the thread in question.)

Here's my test with conductor and foil, where I derived the 5pF figure from guitarnuts2.proboards.com/thread/7725/capacitive-coupling-various-guitar-parts . Note that any added capacitance below 200pF (or higher) is very unlikely to be audible, so 5pF, 15pF, it's all nothingness. A 22nF tone cap, for example, is 22,000pF  orders of magnitude greater than what we're dealing with. 

In the specific cause of pickup cavity shielding, there is potential for eddy current losses as well, but again, that depends on proximity and shielding thickness. The actual brass covers on pickups cause extreme eddy current losses, but a thin layer of shielding around the pickup only causes very very slight attenuation. I did a foil tele bridge plate tet here www.tdpri.com/threads/telecaster-bridge-plate-testing-brass-steel-thin-thick.922149/ , the foil caused less attenuation than any full thickness bridge plate, and unlike cavity shielding, a foil bridge plate perfectly bisects the magnetic field. I've also tested shielded Strat pick guards and found even less attenuation than with the kitchen foil. 

[timtam]

The latest suggestion for shielding SCs seems to be foil with a gap ...

www.premierguitar.com/articles/26279-mod-garage-how-to-shield-single-coil-pickups

Re cavity shielding, there are a small number of youtube vids that include before and after recordings and do show less noise after .. albeit much smaller than the number of people showing 'how to shield' but including no evidence of whether it made any difference or not. OTOH I don't know of any vids that have before and after recordings that show no noise difference (perhaps there are some people who found that ... but they were too embarrassed to show they wasted their time !?).

[antigua]

Dec 29, 2019 20:41:42 GMT -5 timtam said:

The latest suggestion for shielding SCs seems to be foil with a gap ...

www.premierguitar.com/articles/26279-mod-garage-how-to-shield-single-coil-pickups

Re cavity shielding, there are a small number of youtube vids that include before and after recordings and do show less noise after .. albeit much smaller than the number of people showing 'how to shield' but including no evidence of whether it made any difference or not. OTOH I don't know of any vids that have before and after recordings that show no noise difference (perhaps there are some people who found that ... but they were too embarrassed to show they wasted their time !?).

This method adds over 100pF capacitance, so it's a tradeoff. 

[stratotarts]

Dec 29, 2019 20:41:42 GMT -5 timtam said:

The latest suggestion for shielding SCs seems to be foil with a gap ...

www.premierguitar.com/articles/26279-mod-garage-how-to-shield-single-coil-pickups

Re cavity shielding, there are a small number of youtube vids that include before and after recordings and do show less noise after .. albeit much smaller than the number of people showing 'how to shield' but including no evidence of whether it made any difference or not. OTOH I don't know of any vids that have before and after recordings that show no noise difference (perhaps there are some people who found that ... but they were too embarrassed to show they wasted their time !?).

Not sure if Wacker got the gap idea from me (since I published information about gapping in 2014 here: link . However, I found in that situation, that presence of the gap introduced only a 0.5dB difference in the peak response. Strat pickups have a plastic cover - I wonder if anyone has ever tried shielding the inside of those?

[antigua]

I'd think shield-painting the inside of Strat pickup covers would be especially easy, but I can't help but think at the end of the day, it doesn't make that much difference. The pickup is primarily a received of magnetic noise since it has some 8,000 loops, and that's a lot more significant than is the lack of RF shielding. It probably makes more sense with a humbucker, where you've addressed one source of noise and now are mostly limited to one remaining source of noise.

I've been interested in testing the effectiveness of shielding, but I can't think of a good representative noise source, because noise comes from various places. The worst I ever had was a ham radio operator one block away, I could hear his every word come out of my guitar amp, and it didn't matter at all what pickups I was using. 

[pablogilberto]

Sept 24, 2016 14:08:14 GMT -5 antigua said:

Guitar Cables


This is invariably where most of the capacitance comes from.


Fender 18': 547 pF






Monoprice 1/4 10' "instrument cable", 916 pF



So you can see the Monoprice is substantially worse, despite being shorter. A few possible reasons are 1) larger diameter lead wire in the center 2) less insulation between the braded shield layer and the lead center wire 3) capacitive male jacks on either end.

After seeing how bad my 10' Monoprice cable was, I bought this "low capacitance" 10' cable from Amazon... www.amazon.com/gp/product/B00PJ12WYC/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

They claim "Very Low Capacitance", so what does the survey say!?



411.6pF, or 41pF per foot. Not great, but not as bad as the Monoprice cable. I certainly wouldn't say this is "very low capacitance".


            

Hi antigua

Based on this, what do you think is the capacitance per foot value of a decent guitar cable?
Do you know any list of guitar cables and their respective capacitance per foot?

What specific guitar cables brand/models do you suggest?

Thank you!

[antigua]

Jan 8, 2020 0:33:20 GMT -5 pablogilberto said:

Sept 24, 2016 14:08:14 GMT -5 antigua said:

Hi antigua

Based on this, what do you think is the capacitance per foot value of a decent guitar cable?
Do you know any list of guitar cables and their respective capacitance per foot?

What specific guitar cables brand/models do you suggest?

Thank you!

The Roland Black Series cable is pretty good, 31pF per foot. There are some advertising capacitances as a low was 20pF per foot, but they either charge a lot or they're not available through reputable retailers, so I haven't messed with them. I want to avoid high capacitance, but since none of my guitar cables are in excess of 10ft, I don't need to do any better than 31pF per foot. Also the Line 6 G10 wireless has an equivalent of about 130pF overall, so long before I have to worry about length, I'm sooner going wireless. 

[pablogilberto]

Jan 8, 2020 2:57:56 GMT -5 antigua said:

Jan 8, 2020 0:33:20 GMT -5 pablogilberto said:

Hi antigua

Based on this, what do you think is the capacitance per foot value of a decent guitar cable?
Do you know any list of guitar cables and their respective capacitance per foot?

What specific guitar cables brand/models do you suggest?

Thank you!

The Roland Black Series cable is pretty good, 31pF per foot. There are some advertising capacitances as a low was 20pF per foot, but they either charge a lot or they're not available through reputable retailers, so I haven't messed with them. I want to avoid high capacitance, but since none of my guitar cables are in excess of 10ft, I don't need to do any better than 31pF per foot. Also the Line 6 G10 wireless has an equivalent of about 130pF overall, so long before I have to worry about length, I'm sooner going wireless. 

I have tested this cable and it measured 321.3pF (32.13pF per foot).






I have another one which is  380pF for 10ft or 38pF per foot.



1. For a 10 feet cable, will 310pF vs 321pF will make any noticeable sonal difference?

2. Does a 10 feet guitar cable with 380pF can still be considered low capacitance?

3. "Also the Line 6 G10 wireless has an equivalent of about 130pF overall", how did you test this? Can you share your method so I can also test other wireless systems.

4. Let's say I have a wireless system with the exact equivalent capacitance of another guitar cable, does this mean that they will sound the same? Or do I still have to check and consider other factors?

Thanks!

[antigua]

Jan 8, 2020 7:44:33 GMT -5 pablogilberto said:

Jan 8, 2020 2:57:56 GMT -5 antigua said:

I have another one which is  380pF for 10ft or 38pF per foot.



1. For a 10 feet cable, will 310pF vs 321pF will make any noticeable sonal difference?

2. Does a 10 feet guitar cable with 380pF can still be considered low capacitance?

3. "Also the Line 6 G10 wireless has an equivalent of about 130pF overall", how did you test this? Can you share your method so I can also test other wireless systems.

4. Let's say I have a wireless system with the exact equivalent capacitance of another guitar cable, does this mean that they will sound the same? Or do I still have to check and consider other factors?

Thanks!

That's good to know about that cable. I think in order to get as low as 20pF per foot they require some exotic insulator with a lower dielectric value than the waxy looking plastic that is typically used. 

1) 310pF verses 321pF is a very trivial difference, there's no chance you could ever hear any resulting difference. It's hard enough to hear difference as with 100pF added or removed. 

2) 38pF per foot is average, not especially low. 

3) Here's a post about the G10 www.strat-talk.com/threads/the-capacitance-of-line-6-relay-g10.467237/ , I measured a pickup through it, and calculated the capacitance based on having a known inductance and resonant peak for the pickup. With inductance and peak frequency, there are online calculators that handle the work of calculating the capacitance of the parallel RLC circuit. 

4) the will mostly sound the same, the other factor is that the input independence of the wireless transmitter might differ from that of the guitar amp, and that can cause the Q factor to be a little higher or lower than it would be otherwise. The wireless units doubles as a buffer between the guitar and the amp. 

[stevewf]

Interesting, even 6 years later. Of particular interest to me at this time because I'm doing some bench-top testing in order to finalize the guts of a guitar mod.

Question: How to compute the capacitance that's added by my test cables?

My setup:
For testing, I have the guts of that Strat-type guitar on the bench - minus the pickups (the "heart"?), which are mounted in the guitar... so it's the switches, pots and capacitors that are remote. I do this so that I can swap capacitors, pots, try different coil combos including some Half-Out-of-Phase and try three-coil combos, etc. without having to dismount the pickguard for each change. While on the bench, the guts are attached to the guitar using 6 feet of humbucker wire, i.e. four-lead shielded 22AWG braided wire with foil shielding. For ease of reference, I'll start calling these wires "HB cable." In fact, since there are four coils in the guitar, I use a pair of those 6-foot HB cables. The two HB cables are loosely paired (not twisted together, but also not purposefully separated from one another).

What I'm wondering is how much the HB cables are affecting the tone. I'd like to know this so I can at least imagine how much brighter the guitar will be once I put the guitar together, because at that point, the 12 feet HB cable will no longer be in the design; therefore, the finalized guitar differs from its test configuration. If this difference also includes a significant difference in capacitance, it might affect my choice of capacitors or pots in the guitar's design. Judging by earlier posts in this thread, I can probably ignore it if my HB cables add a hundred pF, but I probably shouldn't ignore it when that number approaches 1,000pF.

Some numbers from my HB cable: 
I got me a relatively inexpensive LCR meter, so I can measure the capacitance of things including the HB cable. A problem is that I don't know how to use the values I find. Maybe Nutz can help.

If I clip my LCR's red lead to one of the internal wires of one HB cable and and the black lead to another, I read 107pF (total, over 6 feet). If I clip two of the HB cable's leads together in the LCR's red clip, that number rises to 137pF. If I test a single HB cable's lead with its shield, I get 190pF (again, these measurements are using all 6ft of HB cable).

Since I use a pair of 6-ft HB cables, I also measured capacitance across them. The added capacitance was very low (like 3pF). Remember, the two HB cables are not tightly coupled - in some places, the outer jackets touch, while in other places, they're up to 2 inches apart. I think this added capacitance is negligible and may be ignored, so I can focus on a single HB cable.

So the refined question is: what arithmetic formula do I use for estimating the total capacitance of the HB cable while it's in use? Let's say I'm using only one coil in the guitar, and its leads are in the same HB cable. To compute the total capacitance added by the HB cable, do I use 107pF+190pF+190pF=487pF? That would be a pair of leads plus a lead with the shield, plus the other lead with shield. Or do I count the shield only once, i.e. 107pF+190pF=297pF?

And then, let's say I'm using one HB cable to connect two coils, so all four of the HB cable leads plus their shield are in the circuit. How many combinations of wire pairs do I assume? Do I take all the combinations and add their capacitance, i.e. 6 pairings of leads plus shielding, i.e. (107pF x 6) + 190pF = 855pF?

855pF will, I think, affect the tone noticeably, whereas 297pF only marginally, so knowing which to use could drive my choice of components. Thanks for any Nutz help!

[antigua]

Capacitances add, so it's all additions. The way to measure capacitance, for the most part, in the humbucker cable is shield to any of the inner wires. 

If I were you, with the pickups and controls six feet apart, I'd use non shielded hookup wire (two long unshielded wires, like how Strat pickups come stock) so that you get almost no added capacitance. The capacitance between the pickups and the controls will give you different resonant peaks and tone control behavior when the cable is six feet versus one foot, or zero feet. Before I understood this, I tried, for example, having a tone control in a foot pedal, and I got terrible results without understanding why.  

[ecmalmo]

I tested a couple of the ”house brand” cables of the big european retailer Thomann. The 3 meter cables measured at 330-360 pF, so pretty good comparatively at around 30pF/feet.

[carlosg]

Do you compared single conductor and 4 conductor which has les capacity?
And which wire has les capacity twisted teflon or twisted cloth?
I don't ask about pvc, because I know it's worst.

[zolko60]

There happen to be some low capacity guitar cables made by manufacturers that measure and publish their specs. I don't buy unspecified capacity cables any more and try to keep below 350pF.
Here is a chart:


Sommer Spirit LLX 52pF Shootout 'Black Powder' Cables!

Van Damme Silver Series Session Grade Lo-Cap 55pF

Best-Tronics CA-0446 66pF

Connectronics Rockflex 66pF

George L's .155 67pF*

George L's .225 67pF*

Hosa CGK 68pF

Klotz AC110 70pF

Mogami 3368 70pF

Gepco XB20UB 73pF

Sommer Stratos 75pF

Klotz Titanium 75pF

Sommer Classique 78pF Shootout 'Shooting Jacket' Cables!

Sommer Spirit 78pF

Sommer Corona 78pF

Cordial CGK 122 82pF

Sommer Tricone XXL 85pF Shootout 'Boot Hill' Cables!

Sommer Tricone MKII 85pF

Sommer Spirit XXL 86pF Shootout 'Gun Smoke' Cables!

Cordial CGK175 88pF

Cordial CGK Road 75 88pF

Van Damme Pro Grade XKE 90pF

Van Damme Pro Grade Classic XKE 90pF

Van Damme Silver Series Session Grade Flat-Cap 90pF

Adam Hall KIK122 95pF

Klotz AC106 95pF

Proel HPC140 105pF

Hosa Zaolla Silverline 105pF

Klotz AC104 115pF

Whirlwind Accusonic+1 115pF

Conquest Sound USA 1 115pF

Conquest Sound TL 115pF

Proel HPC110 120pF

Proel HPC130 120pF

Adam Hall 7115 122pF

Van Damme Silver Series Session Grade Hi-Cap 125pF

Sommer Colonel Incredible 130pF

Mogami 2524 130pF

Cordial CIK 122 130pF

Gotham Audio GAC-1 146pF

Belden 9778 148pF

Canare GS-4 154pF

Mogami 2319 155pF

Canare GS-6 160pF

Free The Tone CU-416 160pF

Belden 8412 190pF

source: www.shootoutguitarcables.com/guitar-cables-explained/capacitance-chart.html