I really have serious doubts in my mind about the validity of the little demonstration at the conventions, you know the one where they take the little stick of spruce between secure ends, have a little crown bent in it at rest between those ends, and insert a business card at one of those ends and show how much more crown has happened in that little stick of spruce. It's a fun little thing to show, but I really don't know how much that concept, the arch supported crown, bears any similarity in a piano. Just a couple of things that come to mind. That ain't much of an arch! Seriously, if you want to get into measuring things, measure how long the soundboard is across the length of that crown, and then measure how long that soundboard is across the same length without the crown. It ain't a whole lot different. And for those who work with soundboards, as in shaping and building, do you realize how soft even Sitka spruce is? All you have to do is drop a pencil on it while you're working over it and there's a dent in it! Spruce is soft. And it will compress, especially under the load of a half ton or so of downbearing. (This might be another place to put in a little plug for rib supported crown!) Any difference that the ol' tension resonator might make in the actual crown of the board, I would think, would probably be temporary at best. All that being said, I do like the 'tension resonator' that M & H used(s?). I think it makes for a very solid support system for the rim by tying it all together very solidly. And I suspect that THAT is one of the things that makes these pianos so wonderful to work with. The more solid the rim of a piano, the better termination that soundboard has as it attaches to the rim. This is a good thing! Ya know, I'd love to hear what a piano made out of a concrete rim would sound like. Only thing, I have a feeling we'd have trouble finding piano movers! 'Nuff comments from the peanut gallery. (Just some random thoughts anyway...) Have a good day, folks! Brian Trout Quarryville, PA btrout@desupernet.net ----- Original Message ----- From: "Richard Moody" <remoody@midstatesd.net> To: "piano tech" <pianotech@ptg.org> Sent: Tuesday, February 06, 2001 1:42 AM Subject: rim supported soundboards tesnion resonator rods > > > > >But certainly if the rim did spread out a bit, it would tend to flatten the > >board. So I should think the rods would help maintain crown. Yes? No? > > No. > ............................................................................ .... > .................................... > > > There is nothing preventing piano makers from using the rim to support a crown. > Whether it worked or not is another story. Yet according to Dolge, the "Tension > Resonator" patents of Richard Gerz in 1900 were supposed to do just that. > > "...the purport of which is to regulate the pressure in the arch of the > soundboard against the strings and to assist the vibratory efficiency of the > entire soundboard...... Another function of this resonator is to restore the > original arched form of the soundboard....[to]draw together the entire rim upon > which the soundboard is fastened, and force the latter back to its original > arched form, reinstating and enlivening the vibratory action of the entire > board. ...the tension rods can be screwed up, either simultaniously to bring > pressure upon the entire board, or individually if any part of the soundblard > should show a pronounced flatness. They are furthermore of great value in > maintaining the correct form and shape of the rim. This invention has been > applied to all the grand pianos made by Mason & Hamlin since the granting of the > patent. " > (Alfred Dolge, Pianos and Their Makers. p110) > > I have heard considerable debate about what actually (if anything) was > accomplished by the rods. Never the less if M&H did design a rim to support the > sound board arch the concept was at least given a try. The interesting part of > the debate to me is whether this is an efficacious way of maintaining the crown. > I am not sure anyone knows, unless they are/have actually used it. > I wonder if makers have put soundboards by themselves in a room with > variable humidity and measured dimensional changes, the arch in > particular. ---ric > > >
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