More CC vs RC questions was RE: Killer Octave & Pitch Raise

[Richard Brekne]

Hi again David

I think the key here is that one views the stiffness of the assembly as 
a whole, not the panel isolated from the ribs.  At least thats what I'm 
hearing from the rib crowned and supported camp.  CC people I've talked 
to seem to think differently, that there is an acoustical difference 
(and I agree.... no value judgment included) when the total stiffness of 
the assembly is the result of a completely different contribution from 
each of the component parts. This seems on the surface of things to make 
sense, and I have difficulty imagining anything else frankly.  Another 
point about the <<acoustically equivalent>> line that bothers me is that 
any such equivalence must by definition be only a very temporal state, 
as much of the entire stiffness of the CC assembly is the result of the 
degree of compression at any given time. Since this in turn is the 
result of MC content then there could be at best only a small window of 
RH levels where anything near to the same stiffness to mass ratios could 
exist between a CC and RC&S board.

Personally.... it seems evident from several standpoints that the two 
assemblies yield different acoustical  results and these behave 
differently over time. The value judgments that relate to the 
performance of each is to my mind nearly 100 % a subjective matter.

Cheers
RicB


One other comment.  I think it's very likely that the RC&S board is more
predictable and controllable and takes stress off the panel which
increases longevity of the system for all the reasons previously
mentioned.  I'm all for controllability, predictability and longevity.
However, what I would like to know (without having to take on the
impossible--for me at present--task of trying to build two boards in
order to compare), is whether, all other things being equal and for the
period that they are functioning to their capacity, the RC&S and the CC
board are acoustically equivalent.  No value judgments here.  I've heard
both and both will produce good sounding pianos.  But do they produce
equivalent sounding pianos.  This question is somewhat rhetorical,
though please feel free to answer if so inclined.  The engineering
issues are one thing, the acoustic result of those engineering decisions
may be another.  And if they both produce good sounding pianos but
different sounding pianos, it might be good to get a handle on what
those differences are.  Or maybe I'm just chasing the untamed ornithoid.


David Love