D.L. Bullock took issue with something I said about crowning a soundboard
that it did not aid in sound production. I would like to clarify that,
in case someone else took what I said wrongly.
My point was that the crown of the soundboard is necessary to support
the pressure of the strings. A crowned shape, in and by itself, does
not contribute somehow magically to the tone of a piano, and I don't
care how many soundboards you hit with your fist to see what the
soundboard sounds like, it has nothing to do with tone production--
of and by itself. It has everything to do with bearing and the ability
to support downward pressure.
One of the design features of the Knabe was the fact that the bass
strings had no downbearing at all, and I have run into several Knabes
with over .020 negative downbearing. I don't agree with work like that,
and I did crown the board, but I have to admit honestly that it didn't
help the tone at all, even though I could measure about a +.005 bearing
after it was tuned. I felt better about it, but in actual practice it
was a lot of work for nothing.
Yamahas are very well designed pianos. I didn't realize that they were
designed without bearing as mentioned, I believe, by Bernt Damm. Still,
if in fact they are, it just means to me that the designed horizontal
string plane is a bit lower to compensate, and that piano will not be
hurt tonally in any way. I cannot imagine Yamaha making such a basic
compromise, as detailed as they are in every way, and determined to
have some of the finest pianos made. So that, in itself, if true,
would also point up the fact that crown is not a necessity when not
required by the overall design.
Some of the finest-sounding pianos I have ever played turned out to vary
widely in their degree of crown in the board. It seems as though the
criteria is more the wood itself, and the percentage of perfect
quartersawn in the makeup of the board. The age-old saying that "some"
downbearing is enough has always been correct.
Piano designers would both agree and disagree with different philosophies
like "to crown or not to crown," but the one thing they would all agree
on is this: Sitka Spruce is the best medium for soundboards because it
happens to be the strongest material for its mass yet found, and is
easily dried and cured, and so becomes very stable. The less down bearing
used, the less crown and the less strength is needed, too. Soundboards
have been made from everything from a form of cardboard and parchment
to metal, and all experiments have claimed satisfactory results (Alfred
Dolge, Pianos And Their Makers, pp 106-111). Hmmm. I wonder what a
parchment soundboard would sound like if you hit it with your fist??