Recrowning/bridge wedging

[Danny Moore]

Jim wrote:

> The idea of the Golden Gate Supension bridge is that a thin bridge can
> be suspended by cables mounted from tall towers. My idea for a
> soundboard was that instead of having a crown, the soundboard would be
> in tension which is a tiny bit more analogous to the tuning fork on
> sprung spruce board.

Jim, and other interested parties,

Isn't the standard spruce board in effect a "tenstion" soundboard.  I'm
sure you've more experience than I, but when rebuilding soundboards,
I've noticed that when one removes the go-bars after the glue has set
and the soundboard has had a chance to re-absorb the ambient humidity,
the crown is really more apparant than after it is glued to the rim.
I've always likened this to a bi-metallic bar as used in thermocouples.
It seems to me that the unloaded soundboard is "crowned" as a result of
tension, then controlled by the amount of downbearing.  In my opinion,
too much downbearing is as detrimental as too little.  Also, it seems
that, in rebuilding, the only control the rebuilder has over impedance
is downbearing, as the rebuilder is working within the constraints set
forth by the original designer/manufacturer.

Thanks in advance for your thoughts.

Danny Moore
Houston Chapter