Replacing acoustic bolt-on on w/different scale conversion neck (intonation question)

Discussion in 'Luthier's Corner' started by blueshand, Jun 13, 2018.

  1. blueshand

    blueshand Junior Member

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    I have an acoustic that I really like the body shape of and thinking about replacing the bolt-on neck with a conversion neck of shorter scale (23.25" replacing 25.5").

    Since the bridge is a standard nylon saddle with no intonation adjustment, will this be a problem in changing the scale with a conversion neck?
     
  2. Freddy G

    Freddy G V.I.P. Member

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    It will be a problem if after you bolt the neck on the saddle isn't in exactly the right place for the new scale length.

    What guitar do you have and what conversion neck are you looking at?
     
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  3. C_Becker

    C_Becker Dat Gibson smell

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    The distance between the nut and the 12th fret needs to be equal to the distance between the 12th fret and the bridge, otherwise you'll never get chords that sound right.

    So unless you also move the bridge, the answer is no.

    EDIT: oops, overlooked the part that said "conversion neck"
     
  4. blueshand

    blueshand Junior Member

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    In researching this, I read that the saddle not being in the right place won't be an issue, it just means that there won't be as many frets to work with. Is this true?

    It's a Fender Jazzmaster acoustic:

    [​IMG]
     
  5. MooCheng

    MooCheng Senior Member

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    I'd be surprised if it works,
    given that the point the neck meets the body (usually 12th or 14th fret) is a fixed point, shortening the scale would reduce the distance from the nut to the 12th fret. This reduction needs to be reflected between the 12th fret and saddle. In other words the bridge would be in the wrong position.

    23 1/4 from 25 1/2 is a big jump. Taylor ?
     
  6. Freddy G

    Freddy G V.I.P. Member

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    Hold on a second guys....thats a fender. So....standard 25.5" 4 bolt fender neck yes? There are conversion necks made to replace fender 25.5" necks.....Warmoth for example. That would totally work, because they build the neck so that it will work geometrically when converting from a 25.5" scale.

    But Warmoth doesn't make a 23.25" conversion neck.....so.....:dunno:
     
    Last edited: Jun 13, 2018
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  7. ARandall

    ARandall Senior Member

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    If by 'not many frets' you mean you'll probably get to about fret 3 at max before things sound terrible then yes......oh and the first 3 frets usually sound a bit out of tune on a regular guitar (especially with no intonation adjustment) due to their proximity to the nut.

    So all in all a great way to totally ruin a guitar and waste money to boot.
     
  8. blueshand

    blueshand Junior Member

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    Thanks for your reply! I'm going to hire a luthier to make a custom neck. Yes, it will cost upwards of a grand, but it will be a profile shape of my liking and fit me well.

    Not as many frets on the fretboard closest to the nut. So there will be 20 frets instead of 22, for example (just a guess). And your comment about the intonation being bad in general, can't that be remedied to an extent with thicker strings?
     
  9. Skyjerk

    Skyjerk Meatbomb Silver Supporter

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    Er....more than a grand?!?

    I don't think it should cost nearly that much :)

    As long as the distance from the nut to the bridge is correct for the scale length there should be no intonation problems
     
  10. B. Howard

    B. Howard Premium Member

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    Close but not quite..... The distance from the 12th to the saddle will be slightly longer than the distance from the nut to the 12th, this is called compensation and is how acoustic guitars are typically intonated. Normally we are positioning the saddle or bridge at the correct length but it can be done the other way too. The length of the low E will be longer that the high e. I ran the numbers for you and here are the overall string lengths for that scale on a steel string acoustic guitar from face of nut to break of saddle.
    • Treble "E" or 1st string: 23.331" (± 0.030")
    • Bass "E" or 6th string: 23.446" (± 0.030")
     
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