Intonation weird after nut swap

Discussion in 'Luthier's Guitar & Bass Technical Discussion' started by slide2xxx, May 24, 2015.

  1. slide2xxx

    slide2xxx Member

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    Hi,

    today, I replaced the nut on my PRS with a stoptail bridge.
    I've been using the pre-slotted replacement part.
    So, it's basically just a matter of filing the slots down and gluing in the new nut.
    While I'm not an expert at this, I've successfully filed/replaced nuts a couple of times before.

    However, now, my intonation is weird. The three high strings all were pretty sharp, the three low strings were perfect.

    Sofar, I've never had to adjust anything on a PRS stoptail. Now, the bridge is visibly slanted because the adjustment screw on the treble side is almost all the way in. The intonation is almost perfect again (b string is slightly sharp, still), but I'm left wondering how could that happen?

    The only things that changed are the nut and the strings (however, same set and same gauge were used). I don't see how the nut replacement could physically affect a difference in string length but I guess that must be the reason - somehow?

    Please enlighten me! :)
     
  2. SamBooka

    SamBooka Member

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    sounds like the nuts slots arent deep enough .. I can get my intonation perfect on my strat at the 12th fret but my F at the first fret high e is 6 cents sharp .. F# is 4.5 cents.. etc etc.. it gets better from there. I know this is because of the nut but I dont know how low I can safely go before it starts buzzing..
     
  3. slide2xxx

    slide2xxx Member

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    Thanks!

    For clarification: Intonation was off at the 12th fret.

    The slots seem ok depth-wise. Maybe a tiny bit too high on the treble side, indeed.
    But why would that affect the intonation at the 12th fret so clearly?
     
  4. SamBooka

    SamBooka Member

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    I am only aware of a couple of things that affect the intonation in as far as the nut is concerned..

    ... if the nut is not cut deeply enough

    .. if the contact point in the groove is not at the fingerboardmost point in the nut.
     
  5. mellecaster

    mellecaster Member

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    Not pertaining to the OP's exact question, but more in General...It appears it's time once again to correct the ever increasing Interweb "Myth" concerning intonation on a fretted stringed Instrument. Let's take the 1st High E as an example. You can have the most perfectly cut Nut known to Man w/ just a hair's breath of clearance over the 1st Fret, and take Your accurate Strobe or any good electronic tuner (In this case let's use a Strobe)....set your Bridge saddle to register 100% on the fretted octave note @ the 12th fret...then lightly fret the string @ the 1st fret, and you will see your F just a slight hair sharp....whilst still lookin at your strobe, try the F#...it will be just a little less sharp....then the G...even less sharp....work all the way down to the 12th where again it will be perfect.....It's the nature of a fretted instrument. Of course a well cut nut always helps as much as possible, but it's never gonna be 100% in all positions....Learn it.....Live it....Love it.....but it really does no good to explain it, cause the "Myth" will never Die.....:(
     
  6. slide2xxx

    slide2xxx Member

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    Ok, if the contact points between string and nut would not be at the exact beginning of the nut, this might explain it. The string would then get "longer" at the nut side and consequently the bridge would have to move further back a bit to compensate...Guess I'll have to check this.
     
  7. SamBooka

    SamBooka Member

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    That is why you have guys who tune that G string a little flat... but isnt this alse the reason we have buzz feiten nuts? I have never tried one..

    But yes.. you are correct but there are extremes cases that can be mitigated by a properly cut nut .. and for the rest we rely on temperment and it helps not to play more than one note at once (and definitely no chords.. this is not a piano dammit)
     
  8. Riscchip

    Riscchip Supporting Member

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    Don't PRS guitars come with a compensated nut? If the new nut isn't compensated, maybe that explains the problem. I don't recall for sure if that's the case, though.
     
  9. swiveltung

    swiveltung Member

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    .."..today, I replaced the nut on my PRS with a stoptail bridge...."
    There's your problem!
     
    SamBooka likes this.
  10. slide2xxx

    slide2xxx Member

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    ^^^^^^
    :D:p


    PRS nuts are not compensated but the position of the nut is compensated on a PRS guitar.

    I filed down the slots a bit more today and the problem got a little better. But now they're definitely as low as I will allow them to be and it's still pretty noticeable that the treble side has to be adjusted a lot.

    Still wondering how this came to be.
     

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