Rocking bridges

[Richard Brekne]

Ron Nossaman wrote:

> In the entire bulk of any of the writing that Del, Ron O, or I have
> presented on this list or anywhere else that I know of, you will not find
> anything remotely resembling a claim that any soundboard motion other than
> simple beam deflection of the ribs from static downbearing load is
> calculated by any of the three of us to design soundboards. I wrote that I
> not only didn't know, but didn't care what contribution to the overall
> sound a rocking motion in the bridge produced. I currently have no way to
> quantify it, encourage it, or prevent it in soundboard design, so it is
> beyond my control. It is not even considered in my design process. It
> happens, so be it. Do I want it to happen or not, and to what degree?
> Lacking the means to quantify it, I don't know. I've said something to this
> effect more than once already.
>
>
> Ron N

This is certainly true.  In fact several of us have asked a couple times already as
to just what design issues are touched on directly in this discussion. A few have
gone so far as to dismiss the disscussion as irritable and meaningless in the
practical sense.

While I find the discussion fascinating enough in itself and would like to see it
continue even if it is to remain on its present basis,  I too would like to see the
direct relationship to design issues.

All this being said it would seem to me on the surface of things Ron, that your
present view of how soundboards function would have to affect in some way or
another how you go about designing one. The contrast to the idea that drying and
depleting resins effect soundboard stiffness over time, and the idea that sound
moves through the cell structure of the panel, exciting same into motion and other
such notions seems quiet large to me, and would open for different views for
soundboard construction... whether these view calculate any of the above mention
details or quantities or not.


--
Richard Brekne
RPT, N.P.T.F.
Bergen, Norway
mailto:rbrekne@broadpark.no