Soundboard stiffness vs. string coupling

[Terry]

I think having the strings snake through the offset bridge pins provides
much more positive attachment to the bridge than downbearing. In other
words, downbearing is a minor factor in attaching, or coupling, an
individual string to the bridge. That's what I think. No scientific research
on this topic on my part. But I'll betcha a donut I'm right!

Terry Farrell


> Hello List,
>
> I have been reading the discussion about soundboard
> crown with great interest and feel compelled to add a
> possibly relevant observation.
>
> I am starting with the assumption that one intended
> benefit of the downbearing force is the increase in
> board stiffness.  It's pretty obvious that the
> downbearing of a single string isn't significant to
> accomplish much change in stiffness.  The increase in
> stiffness is the result of the composite force exerted
> by all the strings (however that force is
> distributed).
>
> There is however another design parameter that
> matters;  that is the amount of downward pressure from
> a single string.  This factor is important, because it
> determines the coupling of the individual resonator
> (string) to the bridge/board.  This coupling parameter
> is a separate issue from board stiffness.
>
> So, we have the following problem:  we have to adjust
> two parameters (board stiffness and string coupling),
> but we do it by adjusting one variable - downbearing
> force.  What if the downbearing required to get the
> right board stiffness isn't the same downbearing that
> results in the best coupling from an individual string
> to the board?
>
> That, I believe, is a significant problem in the art
> of the soundboard design.  One way to separate the two
> design parameters is to build a soundboard that either
> doesn't need downbearing in order to achieve the right
> stiffness, or perhaps a board that has an alternate
> means of adjusting the stiffness.  Then, it would be
> possible to adjust the downbearing of each string just
> for the purpose of tweaking the coupling of the string
> to the board.
>
> Optimizing two parameters with one adjustment can be
> tough.
>
> What do you all think?
>
> Vladan
>
>
>
>
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