Still interesting, Ron. What I was thinking was that it would be dead easy to test the effect of differing rib contours in the "killer" area, for anyone who installs soundboards. Just take the tired old soundboard they are about to replace, and use a router and/or plane to thin one side, with the strings still on and at pitch. Possibly they could add mass to the other side as well, by gluing or clamping something to those ribs. They could even test thinning the front on one board and thinning the rear area on another, and see which seemed more effective in changing the tone. (If _either_ made any difference!) One could think about weirder options, too, such as not attaching the board to the belly in the problem portion, possibly even routing it out some clearance, and seeing if the "cantilever" made any difference in freeing it. Or one could support it with narrow feet, like a violin bridge, with room to vibrate in between them. Possibly clearance might give it some room to wander during humidity challenges, too, so it wouldn't crush and flatten as much. Thinking about torque, I started to wonder about the shape of the piano. There is the curve, which surely is there for some reason other than providing a cosy spot for a soprano to stand. If I remember (Les could help here!) George Stecks had a big wide end. Did some of the older pianos have a straighter edge? I wonder what would happen if the rear area were made more extensive and better supported, and the soundboard were a lot freer and more lightly supported from the cutoff bar you were talking about, all the way to the right end. As the board narrowed at the treble end, perhaps enough support might be provided by the rim, so the area wasn't pinched between the rim and the belly. I've never been at all happy with the tone and clarity in octave 7, in any piano. Still fun. Sorry, Horace <g> Susan ------------------------------------------------------------ At 06:21 PM 12/8/97 -0600, Ron wrote: >Interesting thought. Might change the frequency response on one side enough >to not cancel the other and kill the tone. > >Observation: Even if this minimized or canceled the immediate tone problems >in that area, there would still be the problem of torque with humidity >changes. I think this is what drives the board flat at this point far faster >than it flattens elsewhere. Sort of a "saddle" effect, with the killer >octave at the low point of the curve. I think both the tone problems and >early failure in this area are from the same problem. Tag! > >Ron > >At 11:11 AM 12/7/97 -0800, you wrote: >>Curiosity aroused: >> >>The "killer octave" has equal lengths of rib fore and aft of the bridge, and >>the tone has trouble there. Has anyone ever tried making the ribs the same >>length fore and aft, but making them much lighter and more flexible on one >>side than on the other? >> >>What fun ... reminds me of that great string seating thread. >> >>Susan >>----------------------------------------------------------- Susan Kline P.O. Box 1651 Philomath, OR 97370 skline@proaxis.com "With a little more courage, I could get myself into a lot more trouble." -- Ashleigh Brilliant
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