Strings riding up (was Tuning stability)

[David Skolnik]

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At 09:29 AM 4/8/2004 -0500, Ron wrote, in response to Fred Sturm:

>>I wonder what
>>basis there is for our notion that bridge tops should ideally be flat.
>
>Fred,
> From a practical engineering standpoint, the flat top is a balance or 
> compromise between termination quality and durability. Presuming positive 
> front bearing (angle between bridge top and speaking length), it gives a 
> more defined and positive termination point at the edge than a top that 
> is curved to be tangent to the string plane, while being less easily 
> crushable (and cheaper to build) than a top that is grooved or "V'd" down 
> the center.
>
>>In fact, maybe a mild curvature would be better
>>theoretically, both for transfer of energy and for durability. Possible, 
>>I'm not
>>saying it's so.
>
>I don't think so. It's that mild curve in existing bridge caps, with loose 
>pins, that makes the false beats we love so much to hear in the treble 
>third of the scale.

What about a mild curve WITHOUT loose pins?  I don't think there has been 
any determination that a curve in the bridge surface has, in itself, 
anything to do with false beats OR other termination distortion.  It simply 
has to be taken into account when measuring and discussing downbearing.

>>    How is load transferred through bridge to board?
>
>The string moves the bridge, and the bridge moves the board, which moves 
>the strings, which move the board, etc. - until the string energy is 
>absorbed in the internal friction of the system and dissipates as heat. A 
>piano is, after all, a low efficiency space heater.

Is that what you meant, Fred?  You asked about the load, not the 
vibrational energy?  I'm not sure why you would want to, or if you meant to 
steer back into that snake pit.  I don't recall that debate being concluded 
with anything other than an armistice, so Ron's portrayal of the sequence 
of energy transfer, even if correct, must stand as his opinion. There are 
others.

David Skolnik 

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