what is downbearing?

[Richard Brekne]

JIMRPT@aol.com wrote:

> ...that being said even a board which 
> has been 'damaged' by compression may be capable of providing very noice tone. 
> I think this has to do with extent of damage, original downbearing, etc.

In fact... and to be dead honest, given the definition of compression 
damage as it has been given, one is forced, IMHO, to agree that the vast 
majority of compression set damaged pianos do indeed yeild a very fine 
tone, and continue to do so until detrimental factors other then 
compression set by itself come into play. One can easily find numerous 
examples of pianos that have suffered through the effects of compression 
set for 80 - 100 years and yet have very fine tone and sustain.


>  A board which might measure "flat" while strung may display considerable 
> crown when unstrung and it is this 'unstrung' crown which supplies the ability of 
> that particular instrument to produce a very acceptable performance in the 
> volume/sustain area.
>  There are so many examples of pianos with little or no crown, including 
> those which actually were made with reverse crown, which sound very nice that 
> "downbearing" is just a portion of the total picture. Than there are the bridge 
> agraffe thingees, like Ed's little Sohmer grand which actually have 'upbearing' 
> in a portion of the scale and 'downbearing' in another portion of the scale 
> and these were/are not bad sounding pianos...but they do sound different than 
> what we are used to. :-)
> 
>  One of the things I appreciate about Baldwin's Accujust® sytem is that it 
> has allowed me to experiment, non-scientificallly, with down bearing and the 
> requirements therof. It always surprises me how little down bearing it takes to 
> produce a wonderful, if not optimum, sound.
> 

Grin... amazing  aint it ?

>  I belive it is the interplay of upward pressure of the board in conjunction 
> with downward pressure of the strings that is the main determinant of such 
> qualities as sustain and volume and this can not be a function strictly of either 
> downbearing or crown alone.
> My thoughts.
> Jim Bryant (FL)

In the end... what seems to come most clear is that the impedance of the 
soundboard at critical areas needs to be a good match to that of the 
strings which are asked to drive it, and a good match seems achievable 
in several ways. Downbearing, and crown are just two factors in at least 
one strategy for building sounding boards that adress the question.

Cheers
RicB