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visual representation of different scale lengths

Discussion in 'Setup & Repair [DB]' started by Thumpie, Oct 31, 2012.


  1. Thumpie

    Thumpie

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    For those interested,

    I just created a visual representation of the difference between a 41" and 41.75" scale length.

    http://i.imgur.com/s8Ow1.jpg?1

    As you can see by the the small differences between the fingered F on the E string, the individual difference between each position is negligible. It will be less for each note as you ascend the fingerboard.
     
  2. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC Supporting Member

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    Excellent, now please calculate how many cents out-of-tune one would be by substituting one fingered position for the other. Or not... :)
     
  3. Thumpie

    Thumpie

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    Ha! Photoshop won't do that for me!

    I figure the difference in distance to be about 0.056".

    You're welcome to jump on that math if you wanna!
     
  4. Jake deVilliers

    Jake deVilliers Supporting Member

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    20.875/12 = 1.73958
    20.5/12 = 1.708333
    1.73958 - 1.708333 = .0312466 almost exactly 1/32"
     
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  6. Thumpie

    Thumpie

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    That's the average difference each note would be, right?

    I'm interested in the E to F because that would be larger.
     
  7. DoubleMIDI

    DoubleMIDI

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    Fingered string length of a (tempered) halftone above the open string:

    fingered_string_length_a_tempered_halftone_above_the_open_string = open_string_length / 12th_root_of(2)

    Calculate this for 41.5 and 41.75 inches, subtract one result of the other and you have the difference.


    If you want just intonation there are several ratios, depending on function of the interval:

    fingered_string_length_a_tempered_halftone_above_the_open_string = open_string_length * 15/16 (lead tone to root, in C major: B to C in G to C triads)
    fingered_string_length_a_tempered_halftone_above_the_open_string = open_string_length * 24/25 (root to raised root, in C major: C to C# in C to A triads)
    fingered_string_length_a_tempered_halftone_above_the_open_string = open_string_length * 128/135 (minor seventh to major seventh, in C major: Bb to B in C7 to Cmaj7)
    (there are probably some more ratios, but the last is complicated enough, I think)
     
  8. iiipopes

    iiipopes Supporting Member

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    Open E to F on a 41 inch scale = @ 2.30 inches
    Open E to F on a 41 3/4 inch scale = @ 2.34 inches, or a little more than 1/32.

    That isn't a lot, but I went through the same issue with my left hand having a too short pinky, and trying to figure out exactly my largest stretch from E string 1/2 F to D string 1st position 2nd finger F. I then extrapolated the largest scale I can accommodate, and false nutted my CCB down accordingly.

    If a person does shorten the scale, and doesn't want to reset the neck or splice the neck down, then one has to be careful with a false nut so that the string still lays in the groove and is secure coming over the nut witness point, and the string path is smooth so tuning is smooth and there is no risk of the string grabbing or kinking. Shortening can also affect intonation of D or Eb at the heel. On my CCB, it helped better establish the neck as a D neck instead of "in between" as it was before.
     
  9. drurb

    drurb Oracle, Ancient Order of Rass Hattur; Mem. #1, EPC Supporting Member

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    ...can't believe you guys took the bait. :D
     
  10. MrPeel

    MrPeel

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    What is the usual length of a 7/8 or 4/4 bass? My largish 7/8 bass feels noticeably different from the 3/4 bass I had.
     
  11. moles

    moles

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    There was a chart posted in here somewhere - thought I'd seen one anyway...
    My 4/4 Strunal has a playable string length of 44.5". I'd think you'd need at least 43" to be able to claim 4/4. Not that it's anything to aspire to....playing on 44.5 gets old fast some days...
     
  12. Don Higdon

    Don Higdon

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    Is there a point to this thread?
     
  13. Michael Eisenman

    Michael Eisenman Supporting Member

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    Suffice it to say that the definition of a minor second is two bassists playing in unison.
     

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