Guitar cable capacitance -- how much is too much?

Discussion in 'Amp Tech Center' started by King Fan, Jul 25, 2020.

  1. King Fan

    King Fan Poster Extraordinaire

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    So I proudly build up a 10' cable with Canare GS-6 and Neutrik connectors, showed it off to an amp-head friend, only to have him ask, "What's the capacitance conductor to shield?" Looking it up on the Canare site, 160pF/meter. And in fact my 10' cable measures 540pF.

    My 'store-boughten' 10' Spectraflex measures 440pF, about 140pF/meter.

    For comparison, this table suggests 'gold standard' GeorgeL comes in at 67pF/m, and Mogami 3368 is 70pf/m.

    So is it possible to calculate much / what frequency rolloff I'm getting from the 540-560pF in my 10' cable? How much 'better' would it be with say 210pF? (I realize some people actually like their cable to slightly trim the peak-y frequencies...)
     
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  2. tubegeek

    tubegeek Friend of Leo's

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    Very few meters measure small capacitances accurately.
     
  3. King Fan

    King Fan Poster Extraordinaire

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    Excellent point. I know that's true for mine. The fact it came in close to their published figures made me include it. But leave measurement aside; we can just consider the published values.
     
  4. tubegeek

    tubegeek Friend of Leo's

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  5. Paul G.

    Paul G. Friend of Leo's

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    Your assumption is that super low capacitance is "better"?
     
  6. powerwagonjohn

    powerwagonjohn Tele-Meister

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    I have seen Buddy Guy many times. He is famous for walking through the audience while playing. In the old days he had what must have been a 100' cable. He still sounded great. I know not an answer, just an observation.
    Thanks John
     
  7. Henry Mars

    Henry Mars Tele-Afflicted

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    Usually for cables shorter than say 13' you would need calibrated ear drums to hear the difference.
     
  8. hepular

    hepular Tele-Meister

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    "" Albert Collins
     
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  9. Jon Snell

    Jon Snell Tele-Meister

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    Back when I was learning guitar, 1960 ish, the rage then was curly leads.
    I am sure the sound was not as bright as straight leads due to the capacitance and cheapness of the cable.
    I used to play bass but after a course of tablets, got better.
     
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  10. wabashslim

    wabashslim Tele-Afflicted

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    Forget the measurement. Go with the sound. The rest is all marketing BS.
     
  11. RockerDuck

    RockerDuck Friend of Leo's

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    Standard cables over 18.5 feet started to roll off high end. This in not bad as many guitarists used 100ft cables to kill the highs on bright amps, like Marshall super leads.
     
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  12. strat56

    strat56 Tele-Holic Silver Supporter

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    I think if your tone sounds like it needs more high end, then adjust the bass/middle/treble/presence on your amp or adjust the tone control on your guitar.

    I'm not sure trying to fix your tone with a cable is going to work. What if you have to use a different cable one day or you change your brand or gauge of strings or start using a different pick or stop using a pick?

    The tone controls on your amp are there to fix these things.
     
  13. dogmeat

    dogmeat Tele-Afflicted

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    maybe he was just pulling your chain...

    it's not as important as tone wood by any means
     
  14. Lowerleftcoast

    Lowerleftcoast Tele-Afflicted

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    On a ten foot cord?
    Is that a Pythic foot or a Roman foot?

    Reminded me of the "Bridge of Death".

    What is the airspeed velocity of an unladen swallow?

    :lol::lol::lol:
     
  15. King Fan

    King Fan Poster Extraordinaire

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    Really practical, useful, helpful replies, y'all. Thank you!!! Yeah, my buddy is definitely into specs and metrics and numbers. Heh, I was gonna solder up one for him -- I was glad I didn't. He tells me he uses George Ls, of course. I resisted the temptation to tell him I'd rather roll off a few highs than lose the whole dang signal when the George L connectors come loose... :)
     
  16. tah1962

    tah1962 Friend of Leo's

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    If you use a good buffer then you can use any decent/reliable cable and won’t really have to worry about capacitance. Just adjust the tone settings on your amp to taste and let it rock. :D
     
  17. tubegeek

    tubegeek Friend of Leo's

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    13550-576a.jpg
     
  18. TeleTucson

    TeleTucson Tele-Afflicted

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    This is a really well-trodden topic, and is mostly covered under the "Just Pickups" forum where members discuss various electrical engineering models of guitar pickup response, tone, etc.

    The quick skinny is that the dominant factor in guitar pickup tone character is inductance L, and if you're used to "hi fi" systems illustrating frequency response curves, the guitar pickup has a frequency response governed by the "LC" resonance, where the C here is the combined capacitance of the pickup itself along with the capacitance of the cable (and any capacitance of the amp input).

    The response rises at the resonance, and drops off quickly afterwards, giving the characteristic sound we're used to hearing from electric guitars. Once your cable is in the range of several hundreds of pF, it begins to dominate the typical capacitance of the pickup itself which is usually less than 200pF or thereabouts.

    If you want to be geeky, the resonance frequency occurs at 1/(2*pi*sqrt(L*C)), so you can estimate where it starts to drop off if you know L and C. In your case total C would be perhaps 750pF with 200pF from the pickup (750 * 10^-12 for the equation, which is in Farads), but mostly your cable (which I rounded to 550pF), and the inductance for a strat single coil is usually about 2.3 Henries or something like that. This would give 3.8kHz.

    The typical result with a cable is a peak below 4KHz, and the changes you hear result from having the higher harmonics of your strings get cut out by the rapid response drop off. Because of the square root behavior, you need a significant change in cable length to be able to easily notice the difference. Doubling the length of your cable to 20 feet would reduce the peak down to about 2.9kHz for the example above.

    So to answer your question, yes - it's actually pretty easy to calculate rolloffs, etc.

    Look up on the web for a free spreadsheet called "GuitarFreak" from member @johnDH that allows you to get the frequency response curves for just about every variable you can imagine, including cable capacitance per unit length, various different kinds of tone circuits and specific pickup models you may have in your guitar, etc.

    But as others have said, in the end it's your ears that matter. And, if you like the sound of a buffer to eliminate the effect of cable capacitance, use that as noted above.
     
    Last edited: Jul 25, 2020
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  19. tah1962

    tah1962 Friend of Leo's

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  20. jsnwhite619

    jsnwhite619 Friend of Leo's

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    Skip ahead to 9:00 or so and hear the samples back to back. 3', 10', 25', 100', and 200'. The 100' and 200' clips sound like a cocked wah-wah.




    Also, https://www.premierguitar.com/articles/How_to_Choose_a_14_Cable

    The Capacitance Wars and the “Sweet Spot”
    Capacitance, measured in picofarads (pF), began emerging as a buzzword in the late ’90s, and rightly so. It’s probably the single most influential property that affects the sound of a cable. Bill Lawrence—who began designing pickups and guitars for the likes of Fender, Gibson, Peavey, and others in the 1950s, and who pioneered solderless cables—explains why. “The higher the capacitance of a cable, the less highs reach the amplifier. High-capacitance cables shift the resonance towards the lower frequencies, which dramatically alters tone. For example, Jimi Hendrix used a coiled cord with 3,000 pF [of capacitance]. This was the secret of Jimi’s tone: Shifting the resonance frequency below 2,000 Hz on his Strats has a similar effect to a midrange boost. When he recorded and needed a typical Strat sound for some tracks, Jimi switched to a short, low-capacitance cable.” (This also brings up a valuable corollary: The longer the cable, the greater the capacitance—which is why shorter cables always sound brighter.)
     
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