No downbearing ? REVISITED

[Ron Nossaman]

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>The question I'm trying to address in this particular thread is whether 
>downbearing plays more of a role in string / bridge coupling and 
>vibrational energy delivery than is being acknowledged in the original 
>question by Jean-Jacques Granas and in the response by John Hartman.  In 
>its simplest form, I am challenging the implied conclusion that zero or 
>negative downbearing is an acceptable, or desirable condition.

The problem is that your question is much too general and unqualified for 
the specific and absolute answer you seem to be looking for. Is any and 
every soundboard you find out there capable of producing good piano tone 
with no bearing? No, absolutely not. Is it possible to build a soundboard 
that produces good sound with no bearing or crown? Yes, almost certainly. 
Will it look like every other existing soundboard you see out there in the 
world? No, most likely not. As has been explained, downbearing is to 
compress the board to raise it's impedance to meet the requirements of the 
string scale. It isn't to enhance the coupling between the string and the 
bridge surface. The bridge pins do that quite nicely. There is no magic 
energy transfer inherent in the bridge to string interface that the bridge 
pins don't adequately supply. Adding bearing changes sound production 
BECAUSE the added load changes the soundboard impedance.


>Further, the only other questions relevant to this particular thread would 
>address the ability to and method of accurately and consistently measuring 
>the downbearing angles as they exist on the strung piano, not issues of 
>killer octave problems, panel stiffness, crowning method, etc. I had added 
>the disclaimer about not being a rebuilder because I'm not attempting to 
>discuss whether some certain amount of measured angle is too little or too 
>much.

And this has already been addressed many times on list. Measure bearing 
angles with a tool that measures angles directly, like a bubble gage. 
Measure front bearing, back bearing, and overall bearing to get a 
reasonably accurate picture of what you have. Even then, the numbers 
obtained are meaningful only in the context of remaining soundboard crown, 
and how the thing sounds with what is already there.


>Are there any builders or rebuilders out there who would, with no 
>hesitation, put out a product which had zero or negative downbearing?
>
>David Skolnik

With an existing soundboard, no. With a soundboard I had (successfully) 
designed to work with zero or negative bearing, of course. Again - to get a 
meaningful answer, you need to ask an accurate question.

Ron N

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