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
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