Effect of bridge height on tone?

[Dave Nereson]

----- Original Message ----- 
From: "gordon stelter" <lclgcnp@yahoo.com>
To: "Pianotech" <pianotech@ptg.org>
Sent: Monday, January 24, 2005 8:46 PM
Subject: Effect of bridge height on tone?


> It seems to me that energy is transferred to the board
> from the string via "bell-crank" motion, NOT the
> direct waving of the board ( heavy and stiff ) by the
> string ( light and flexible).  As the string
> oscillates it expands and contracts in lenghth, and it
> is this motion, yanking the top surface of the bridge
> for and aft, that is transmitted into an up-and-down
> motion of the board near the bridge
> ( alternately adjacent to its sides )  and these
> vibrations are then sent rippling along the grain to
> the rest of the board surface.
>     Therefore, could it be that increased bearing
> mainly improves the mechanical advantage, via
> leverage, that the string has in tranfessing its
> motion to this most immediate portion of the board,
> and that this is as ( or more ? ) important than any
> increased stiffness to to compression?
>     If my theory is correct, then bridge height would
> probably also be a significant factor in tone, as it
> would also have marked effect on the mechanical
> advantage the string has as it vibrates.
>     Has anyone studied the effect of bridge height on
> tone, all else being equal?
>     Thump

    I haven't studied it, but I tuned a piano with three layers of strings: 
the treble and mid tenor were on one bridge, the low tenor and upper bass 
were on another bridge, and the lower bass strings were strung on top of the 
other two tiers on yet another bridge which was approximately 5 inches high. 
However, the reason for doing this was to make one of the shortest grand 
pianos ever, so any tone-aiding effect of a high bridge was  probably 
canceled out by having such short strings and small soundboard.  It was a 
Goers & Kallman (British).
    --David Nereson, RPT