compression ridges in New Baldwin grand

[Overs Pianos]

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Folks,

Having just completed two months of testing sound board test strips, 
ie. one rib mounted to a strip of sound board (a series of RC 
variations and a CC control group was built, testing them with a 
range of down bearing loads and plotting each for panel deflection 
along the length of the rib), I find the debate on this thread to be 
a bit frustrating.

An analysis of the loads on a typical sound board will reveal that by 
far the most highly stressed ribs are those in the second last treble 
section. This is why the 'killer octave' phenomenon (which perhaps 
could be better named the 'collapsed sound board section') is so 
frequently encountered here and rarely elsewhere on the instrument. 
The ribs in the lower sections are progressively less stressed, while 
in the top string section the bridge runs so closely to the belly 
rail that it is supported to a significant degree by its proximity to 
the belly rail.

I have difficulty accepting Richard B's argument, that because a 
greater percentage of the world's performance pianos come from one 
maker, this manufacturer's technique must therefore carry legitimacy. 
I am unconvinced about drawing conclusions from this market dominance 
theory and would prefer to arrive at a view through experimentation 
(and would commend the practice to others who feel compelled put 
forward an argument). While it is always difficult to determine a 
truth, we must persevere since an answer will be forthcoming if we 
allow ourselves to consider the options.

At this time I am convinced that rib crowning is structurally 
superior to compression crowning. While I believe that both are 
capable of producing a quality tone, the CC design is absolutely 
bound to fail earlier than the RC design.

I note also that some doubt was cast upon Ron N's assertion that some 
pianos have collapsed sound boards before they reach the showroom 
floor. Could I suggest that those who doubt Ron's claim actually take 
measurements from a few new pianos. When Ron first made this claim on 
the list some months ago, I measured several new instruments only to 
find that he was absolutely correct. Currently, I  know of two new 
grand pianos here in Sydney which are being returned to the 
manufacturer next week before being delivered to the showroom. With 
plenty of down bearing, an almost perfectly flat board and a choked 
tone, these pianos are glowing examples of the problem.

Ron O.
-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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Web http://overspianos.com.au
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