No downbearing ? REVISITED

[David Skolnik]

---------------------- multipart/alternative attachment
Ron -

Thanks for taking the time to respond, and and for encouraging greater 
articulation of my thoughts.  So let me try to go through your points 
carefully and, if necessary, ask for further clarification.

At 09:32 PM 2/1/2004 -0600, you wrote:

>>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.

I don't think this is an accurate interpretation of any question I have 
asked.  Looking over my previous posts, I think my questions have tended to 
be quite specific and not necessarily seeking absolute answers, just 
answers which address the question asked.

>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.

What you appear to be saying is that, no matter whether there is positive, 
zero, or negative angle at the front "bearing point edge"(Wapin),  the 
transmission of energy from string to bridge to board is unaffected.

Do you think there might be any difference in vibrational mode and 
transmission performance  between a string which, due to positive 
downbearing, terminates in both the semi-vertical pin plane, as well as the 
horizontal "bearing point edge" plane verses a string which, due to 
negative front bearing, has minimal or no contact with the horizontal 
"bearing point edge"?  Actually, with regard to Negative front bearing, 
another question might be about the difference in impact between the 
Potential Phase, where the direction of the force upon the pin is upward, 
not down, and the  Equalizing Phase, where the string has begun to ride up 
the bridge pin, reducing the upward force, but, at the same time, 
eliminating contact with the "bearing point edge".

>There is no magic energy transfer inherent in the bridge to string 
>interface that the bridge pins don't adequately supply.

Can I take this to mean then that, apart from the impedance-producing 
function of downbearing, a string could traverse the bridge at some 
distance above its surface, coupled by the bridge pins, without adversely 
impacting upon the transmission of vibrational energy to the board?

>>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.

I have used a Lowell gauge for many years.  My Lowell gauge has gotten me 
in deep s.... with a few manufacturers and dealers over the years. Without 
it, I would probably never been aware enough to even raise these questions 
in the first place, so, go blame Tom.  The fact is however, that the gauge, 
when used as directed in the instructions, does not give an entirely 
accurate image of the configuration. The ideas I have about this are either 
already a part of common wisdom, or not.  I'll save them for a different 
forum, unless they prove to be entirely relevant.

>Even then, the numbers obtained are meaningful only in the context of 
>remaining soundboard crown,

I'm not sure I see why things become so relative?  If I am measuring zero 
or negative downbearing, I don't see that it matters whether I have crown 
or no crown for the purpose of examining the coupling mechanics.  Again, I 
am not addressing the question of the proper amount of downbearing for a 
given impedance result for a given board, except and unless you were able 
to answer a previous question, which was, how local the impedance function, 
or, how large an area of non-compression (zero/neg) would you have to have 
before you would expect to perceive tonal degradation?


>>Are there any builders or rebuilders out there who would, with no 
>>hesitation, put out a product which had zero or negative downbearing?
Ron N
>With an existing soundboard, no.

Okay.  This addresses the reality.

>  With a soundboard I had (successfully) designed to work with zero or 
> negative bearing, of course.

This is theoretical.

>Again - to get a meaningful answer, you need to ask an accurate question.

I'm really trying.

Thanks.

David Skolnik

---------------------- multipart/alternative attachment
An HTML attachment was scrubbed...
URL: https://www.moypiano.com/ptg/pianotech.php/attachments/f1/65/02/c2/attachment.htm

---------------------- multipart/alternative attachment--