Shallow ribs on great old boards.

[Overs Pianos]

At 8:29 PM +0100 24/1/05, Richard Brekne wrote:
>
>. . . that compression damage is not really (necessarilly) damage 
>per se at all, that a CC board that has lived a very successfully 
>life and slowly but very evenly been compressed flat will retain 
>(exactly because of said compression) a substantial part of its 
>initial stiffness, explaining why so many old boards seem to perform 
>so acceptably well . . .

I totally disagree that an evenly compressed board will have retained 
its stiffness. If the cellular compression has gone out of a panel 
enough to allow it to lose crown, it will also have lost a 
significant degree of stiffness at the same time. In CC boards, panel 
compression adds to the stiffness of the whole. If you're looking for 
a floppy non-stiff panel that has front-end-punch with less sustain, 
the sunken CC item will do it. There are numerous S-bent killer 
octaves out there to prove this point (which were overloaded because 
they were under-engineered in the first place). There may be 
instruments which sound acceptable, which have what some would 
describe as an ordinary board. But I have no doubt that these 
instruments would have a longer tone (which, in my opinion, I happen 
to subjectively like) if the board had retained that higher level of 
stiffness, which might have been built into it at the time of 
construction.

On several occasions I've had technicians claim that "provided there 
was an initial angle of downbearing set into an instrument, there 
will still be a down bearing force on the board even after 
significant soundboard drop has occurred". It isn't so. No down 
bearing angle results in no loading on the board. Similarly, if a CC 
board has lost its crown, it will have lost significant stiffness. 
Sunken boards might sound OK if there is a working balance between 
mass/stiffness/sound board area remaining.

I strongly suspect that there is some sort of important relationship 
between mass/stiffness/soundboard area which fundamentally influences 
the tonal qualities of an instrument. Please don't ask me to 
elaborate on this matter at this time. This theory remains just that, 
at present.

Ron O.

-- 
OVERS PIANOS - SYDNEY
    Grand Piano Manufacturers
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