[CAUT] pre-stretching new string Wet vs Dry Soundboard

[Richard Brekne]

Hi Don

I understand this much well enough. We've been through para several 
times through the years. I just was not aware anyone had ever made a 
claim that overall sounboard stiffness changes due to seasonal changes 
could account for any real significant change. 

Its an interesting thought to be sure... but I think it needs to be 
documented just  how much change in pitch any given change in soundboard 
stiffness can account for.

Cheers
RicB



    Hi Ric,

    The bridge is not a ridged termination. (coupled motion of piano
    strings).
    If the rigidity changes with humidity then the string may appear
    longer or
    shorter thus affecting pitch. Dean Reyburn refers to this effect as
    "para
    inharmonicity"i.e. Inharmonicity can be different (even sometimes
    negative)
    than the values calculated by length, diameter and tension because the
    bridge and soundboard affect the termination of the string.

    His first efforts to generate tunings relied on measurements of
    length and
    diameter of strings. The generated tunings were then uploaded via a midi
    cable to a SATII.  They didn't always "fit" the piano.

    It is also why "stored tunings" don't work well in areas where humidity
    changes by more than a few percent.

    I believe that some SAT users have documented inharmonicity tends to
    lower
    over time when a piano is kept "at pitch" as the strings conform to the
    bends in their length at the capo bar and the bridge pins.

    At 12:46 PM 6/10/2007 +0100, you wrote:
     >Hi Mike, Andrew... whomever...
     >
     >I am not sure I understand whats being said here.  If a string is
     >vibrates at a given frequency, how does the degree of stiffness of
    the
     >board significantly alter this pitch ? Anyone care to explain the
     >mechanism for this ?
     >
     >Cheers
     >RicB
    Regards,
    Don Rose, B.Mus., A.M.U.S., A.MUS., R.P.T.
    Non calor sed umor est qui nobis incommodat

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