Question about String gauge and intonation

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by deoreo, Apr 21, 2008.

  1. deoreo

    deoreo Member

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    All things remaining equal, that is using the same guitar, if I go from a set of 0.13's to 0.008's (just an example to see the effect) generally how will intonation settings change? Do the saddles go towards the nut as the guage gets lighter?

    I understand how to intonate the guitar, and do so with a strobe tuner.

    Why I'm asking is, if working with a guitar that has a limited intonation range or at their front or rear limit, can I select a string guage that will help minimize the problem?
     
  2. rkchkr

    rkchkr Member

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    While not nearly as big a jump in guage..I have been thinking of going from .009's to .010's and wondered the same thing. SO, FWIW ,having a .046 laying around, I swapped it out for the .042 that was on the guitar. Keeping in mind this was only one string....THAT string....at the 12th fret it was sharp by about 5 or 6 cents.
     
  3. Chiba

    Chiba Gold Supporting Member

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    I've noticed that most times, going from lighter to heavier means the saddles have to move away from the nut, so I would think the opposite would be true as well.

    --chiba
     
  4. Vibrolucky

    Vibrolucky Supporting Member

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    You would have to re-adjust the neck to get the intonation right, the extra tension ( or lack of tension) would most certainly bow the neck changing the distance between the nut and bridge.
     
  5. Dana Olsen

    Dana Olsen Gold Supporting Member

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    That's it, the thinner the string, the more compensation needed relative to the thicker strings.

    Dana O.
     
  6. Tone_Terrific

    Tone_Terrific Member

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    Hadn't caught that explanation before. I miss a lot:phones
     
  7. deoreo

    deoreo Member

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    henry_the_horse - Thank you for the detailed explanation!
     
  8. Supasso

    Supasso Member

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    I think you get it wrong on both counts. Firstly, The 12 fret harmonic does not move with the tuning. It's always at the center of the string length. That's why it's a harmonic point.

    Secondly, the saddle compensation has nothing to do with string's mass - at least not directly. It certainly is not about equaling the string mass at all. When you fret the string, you are basically bending the string toward the fret, bending it slightly sharp, and that's why we need to move the saddle backward to compensate, and thiner strings need more compensation because they get sharper when fretted than thicker strings tuning to the same pitch.
     
  9. Bob V

    Bob V Member

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    Compensation of the saddle, that is, moving it away from the nut, is meant to account for - or compensate for - the fact that a string has to be stretched when it's pressed down into the fretboard. On their own, a lighter string generally needs less compensation. Makes sense picturing the line that the saddles almost make: the saddle for the high E is not too far back from the theoretical scale length of, say 24-3/4" or 25-1/2" from the nut, but the thick, low E is much farther away. Generally, anyway. So in going to a lighter string i'd expect to have to bring the saddles in closer to the nut - except that's not all that's going on here.

    The lighter string gauge will have an effect on the action - by the time you adjust the trussrod then the saddles, the lighter gauge set might be a different distance off of the fretboard, in which case there's a different amount of stretching going on as you press a string down to fret a note. And hence a different amount of compensation.

    There's another factor that probably only comes into play if you have really heavy piano strings: theoretically a heavy string isn't vibrating all the way out to the end, it's as if it's too stiff to vibrate right where it's held against the saddle. As a result a really heavy string is going to need some additional compensation, or lengthening. Just spitballing here, it probably makes no difference but if it did you're still going to expect to move the saddles towards the nut when you string up with lighter strings.

    Then again you could just hit it and see what happens. Sometimes you don't know if the saddles need to come out and get flipped around in an ABR-1 tune o matic until you've gotten all the other ones adjusted just so...
     
  10. EADGBE

    EADGBE Member

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    You may not have to adjust the neck. I'd wait on that. And yes thinner strings tend to need more compensation as they stretch more easily.
     
  11. Supasso

    Supasso Member

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    Sorry for misunderstood you earlier. Anyway, if you drop the tuning to D, the fretted note would sound sharper comparing to the harmonic, simply because the string now has less tension and is more likely to get bend sharper when fretted.

    I think your "move the saddle back to equal the string mass" is simply wrong. Let say if we replace the low e with a string half the mass, would moving the saddle back twice as far make the intonation correct? Obviously not.
     

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