The Soundboard bit.. RC&S

[ed440 at mindspring.com]

>> Ron-
>> This being the case, what is the purpose of creating any crown in the board?
>> Ed Sutton
>
>To provide an opposing spring for the string downbearing, just 
>like with RC and CC boards. The difference is that the crown 
>support comes pretty much entirely from the ribs in the RC&S 
>boards, and either partially or entirely from the panel in RC 
>and CC boards (respectively).
>
>Ron N

And a flat or concave rib could not also provide appropriate springy resistance?  Is there a reason why the convex curve works better?

Ed S.