Hi CAUT-ees This post came in on piano tech and I thought it worth posting here. Interesteds will please read Franks contribution below before reading my reply just after this comment. Cheers RicB Hi Frank. Yes. I think the basic question I'm asking is... can a lack of cross grain stiffness at some point create a situation where the difference between cross grain and along the grain stiffness becomes large enough that the soundboards ability to vibrate well at lower (large) modes becomes inhibited. One of the points in the Five lectures is that cross grain stiffness is needed to equalize stiffness in both directions exactly because of the need to get the total vibrational area of the soundboard vibrating. I'm downstringing to do a couple things over/better on the instrument I am working on... so I can try spreading sand or glitter on the panel and hit the mid-low tenor area of the long bridge to see where it gathers. Aside from the specific job I'm on... this is really interesting as it touches on why older pianos sometimes start developing this kind of sound.. why some new ones seem to have it built it... and suggests a possibility of dealing with the symptom without removing the soundboard. It also adds argumentation on both sides of the CC and RC&S discussion. And on top of that it starts clearing up (in my mind at anyrate) some of what possible reasons designers have had through the years in selection of grain orientation and rib patterns along with rib orientation relative to the grain. So... do you think then if one goes too far (as you put it) in reducing stiffness in the area of the soundboard at question here can cause this kind of thinning / nasalness of the sound ? And if so, does the idea that the lack of cross grain stiffness being enough relative to along the grain stiffness fit in here ? Thanks for your thoughts Richard Brekne ---- Richard Brekne <ricb at pianostemmer.no> wrote: >I'm wondering if a nasal sound... with little or no apparent low end > response can have to do with LACK of stiffness in the fat part of > the soundboard... i.e. in that section that is somewhat front of > the long bridge and bass bridge.... low tenor area. I know this > seems to go contrary to the usual conclusions we'd jump at.... but > it connects with aging soundboards and why they start sounding thin >and nasal... Frank Emerson replies: I can't find the exact posting, but earlier in the thread it was suggested that the soundboard might divide into many small "tweeters" and thereby inhibit the full vibration of the soundboard, as a "woofer." Forgive me if my memory has misconstrued the intent of the statement. I have seen studies of soundboard vibration where black glitter is sprinkle over the entire surface of the soundboard. As different frequencies are introduced at different locations along the bridge, the glitter moves to define nodal lines on the surface of the board. The patterns came out differently for different frequencies. It seems to me that these nodal divisions of the board do not inhibit the fundamental frequency, but work concurrently with it, in much the same way as a sounding string has a complex envelop of multiple partials at multiple frequency. Regarding reduction of stiffness in the bass region of the board, I believe you can go too far in that direction. I am reminded of a piano that makes much ado about its reverse crown and floating soundboard in the bass. To me it sounds much like an old upright where the bass bridge has come unglued from the apron. Frank Emerson
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