Shallow ribs on great old boards.

[gordon stelter]

Interesting. This may be superfluous, but I would like
to mention that some of the best-sounding old upright
pianos I have seen have very wide, shallow ribs. And
no cracks in the still very "live" boards. Knabe.
Ivers and Pond. Mason.
     Not intending to muddy things here. I believe in
and support the idea of rib-crowning. But how did
these allegedly CC boards survive in Georgia for 100
years so well? Lots of varnish?
     Thump


--- David Love <davidlovepianos@comcast.net> wrote:

> I'm not sure that the rib crowned board necessarily
> uses ribs of more
> mass, rather they are taller and narrower instead of
> shorter and wider.
> 
> 
> David Love
> davidlovepianos@comcast.net 
> 
> -----Original Message-----
> From: pianotech-bounces@ptg.org
> [mailto:pianotech-bounces@ptg.org] On
> Behalf Of Richard Brekne
> Sent: Sunday, January 23, 2005 1:59 PM
> To: Pianotech
> Subject: Re: circle of sound
> 
> Erwinspiano@aol.com wrote:
> 
> >  
> >
> >     Ron O. write
> >
> >  Possibly, the ribs on the bigger pianos are also
> > quite heavy relative to their strength. The
> > Imperial ribs are nominally 30mm wide by 23 mm
> > high.
> >    Hi Ron .O
> >   If the Bozy had ribs 30 high by 23 wide ,which,
> is reverse of the 
> > above, then perhaps a different tonal result at
> the higher dyanmic 
> > levels would be more likely. Whadda ya think ?
> >   My goodness this is a very flimsy rib for a
> massive piano but then 
> > this to me  would indicate a purely compression
> crowned board
> 
> You touch on a point I've been scratchin my head
> about for 4 years 
> now... relates to a disscussion between myself,
> Delwin, and Andre back 
> then.  How (if possible at all)  a compression
> board... with smaller 
> dimmensioned ribs and more reliance on the
> compression of the panel for 
> stiffness can be made to yield the same... or nearly
> same acoustical 
> results as a rib crowned board which uses larger
> dimensioned ribs to 
> achieve the same stiffness.  At best it would seem
> to me that their 
> might be some RH level where the two might be
> somewhat similiar... but 
> the requirement for greater rib mass in rib crowned
> assemblies alters 
> the stiffness to mass ratio, and if its compensated
> in any sence of the
> 
> word by less panel mass then at the very least the
> distribution of mass 
> is quite different. Still looking for a good
> explanation here.
> 
> >    Dale
> 
> 
> Cheers
> RicB
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