Reverse Crown Soundboard/Rippen

[Delwin D Fandrich]

----- Original Message -----
From: <Bdshull@AOL.COM>
To: <pianotech@ptg.org>
Sent: June 29, 2001 1:55 AM
Subject: Re: Reverse Crown Soundboard/Rippen


> Some random musings - I have serviced one Rippen cast iron grand with this
> board.

Are you sure that rim was cast iron? Or could it have been aluminum?



> It exhibited classic reverse crown/poor down bearing symptoms - it
> had little power or sustain.  I then checked and found reverse crown,
which I
> believed was not intended by the manufacturer until Del's observations of
> some time ago.  Soundboards seem to have greater durability in Southern
> California than in some parts of the country;  I don't know if this board
> resembles its original state or not.

Probably does. If it is the same model I'm thinking of--was it
flat-strung?--there were a lot of things wrong with the overall design. The
scaling was weak; the soundboard design itself left a lot to be desired; as
you have observed the soundboard mounting was weak; and the list goes on.
Just one more example of Rippen's discontinuous brilliance.



> Just curious, Del:  Why do you think Rippen would use a "liberal dose of
> string bearing" if the board started flat?

Because they wanted CROWN. Up or down, it's still crown.

This is an area that really needs some in depth investigative work. I'd like
to see some testing done comparing a series of pianos of identical pianos
varying only in the amount and direction of the crown and soundboard
loading.



> How important is crown in tone production, anyway?  My favorite personal
> experience is the 6'3" Starr with negative crown I did strings and
pinblock
> on 10 years ago.  I know crown on this one was positive once, based on how
> much negative downbearing it had when I found it!  A conservative
downbearing
> approach gave this piano plenty of sweet singing in the treble.  Could it
be
> that crown isn't so important unless power is needed?  Or does lack of
crown
> set the piano up for more rapid loss of downbearing (all other things
equal)?

Well, all things are never equal. Crown, and the associative string loading,
increases overall soundboard stiffness which contributes to a longer sustain
time. Obviously this piano's soundboard was getting its stiffness elsewhere.
Perhaps from its thickness or from its ribbing. It was getting it from
somewhere.



> The Rippen might not be a good example, with its small soundboard "rim"
> screwed to the cast iron rim;  I wondered about the stability of this
light
> perimeter - could it also have shifted and lessened downbearing?

With a Rippen, anything could have been happening.



> ... might a "K" or 45/1098 with substantial crown and more
> substantial high treble ribbing be a considerably more powerful piano?
> (Duplexing or not...)

Not if that is the only change being made. More substantial ribbing would
give a longer sustain time and less 'power.'

-- ddf