Hi David Since no one else jumped on this I'll offer a couple comments. As to target mass/stiffness ratio I think that rather depends on what it is you are trying to do, what kind of sound in the different registers and sound balance in general you are after, what kind of structural strength you feel is needed, and how you go about achieving these to begin with. As for mass / stiffness ratio in different parts of the piano. Thats been tossed around here quite a bit over the years, especially comparing bass to treble and I am sure you will find all kinds of references in the achives. This same goes to disscussions about the treble fish and cuttoff-bar, tho perhaps to a lesser degree as to how directly they require a rethinking of any mass/stiffness ratio concerns. That said I believe the main purpose of a cutoff bar is simply to reduce the area of the soundboard so as to be able to provide stronger support for the assembly and in some cases to purposefuly manipulate some of the soundboards impedance characteristics. Rib width and height relationship is very well, tho briefly, described in the five lectures. In particular interested readers should check out http://www.speech.kth.se/music/5_lectures/wogram/ribbing.html#height which deals directly with your specific question. I was interested to read Ron O's statement that mass/stiffness ratio contributed to a "propensity for falseness". If he was talking about the same kind of false beats that the previous discussion was based on... then that strikes me as rather significant with regard to indentifying a root cause for those same. Certainly if changing the mass/stiffness ratio alone is a totally isolated issue from loose bridge pins. It would be interesting to gather some relavant data comparing instruments with lots of false beating with instruments that have little. Grin... one could start with Petrofs !! False beat city, yet an overall nice open sound. Cheers RicB ________________________________________________ 1. Is there a target mass/stiffness ratio and how is it described numerically? 2. How does it differ in different parts of the piano? 3. Does adding a cut-off bar and/or treble fish reduce the mass by virtue of a decrease in the area of the board such that some compensation is always required to rebalance that ratio? 4. Does changing the rib width to height relationship influence mass stiffness ratio? For starters anyway. David Love davidlovepianos@comcast.net
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