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calculate the tension if detuned

Discussion in 'Strings [BG]' started by jamersonburton, Sep 27, 2013.

  1. jamersonburton


    Jul 22, 2011
    Can someone calculate the tension of 45-100 d'addario XL nickels (long scale) strings if they were detuned to DGCF (1 full step down).

    In E standard:
    E- 34.72
    A- 40.05
    D- 48.35
    G- 42.52

  2. At what scale? And why?
  3. megafiddle


    May 25, 2011
    You can look up the detuned tension in the tables at the D'addario website:


    That page explains how to use the tables and there's a link near the top of the page
    for downloading the full table.

    All their strings are listed with tensions for various tunings.

    The calculation is relatively simple, though. First find the frequency ratio between the standard tuning tension,
    and the detuned tension. The frequency ratio is approx 1.059 for each half step. So for a whole step, the ratio
    is 1.059 x 1.059 which equals 1.121

    The tension is related to the frequency squared; so square that value to get the tension ratio - 1.121 x 1.121 equals 1.257

    Now just divide each standard tension by 1.257

  4. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    Here is what I get. I don't know why my spreadsheet does not return the same results as the D'Addario chart and I don't have time to check it out now but the results should be close.

    0.100 E-1 36.24
    0.080 A-1 41.70
    0.065 D-2 50.94
    0.045 G-2 42.50

    0.100 D-1 28.76
    0.080 G-1 33.10
    0.065 C-2 40.44
    0.045 F-2 33.72
  5. iiipopes

    iiipopes Supporting Member

    May 4, 2009
    If you're taking the original tension figures off the web site instead of the old pdf download; D'Addario has refigured their individual string tension specs.

    The mathematical formula, however, is the same. Tension varies as the square of the pitch. So the detuned tension will equal (lower pitch in Hz)^2/(higher pitch in Hz)^2 * current tension.
  6. knuckle_head

    knuckle_head Commercial User

    Jul 30, 2002
    Owner; Knuckle Guitar Works & Circle K Strings
    You'll lose about 9 pounds tension per string.
  7. khutch

    khutch Praise Harp

    Aug 20, 2011
    suburban Chicago
    Yeah, my spreadsheet uses the unit weight numbers from the pdf. If they changed the weights then the numbers will change but of course if they didn't measure them right the first time we can't be sure they are right the second time either....
  8. iiipopes

    iiipopes Supporting Member

    May 4, 2009
    They're working on that.
  9. ixlramp


    Jan 25, 2005
    ^ What megafiddle said.

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