This is a multi-part message in MIME format. ---------------------- multipart/alternative attachment ----- Original Message -----=20 From: Richard Brekne=20 To: pianotech@ptg.org=20 Sent: December 03, 2001 12:04 PM Subject: Re: Negative bearing (long) Been reading and weeding through and find much that is interesting, = but this comment caught my eye and I must admit is confusing. I wrote = about modal analysis a year and a half back and you came out and said it = was basically useless in designing soundboards, since the conditions for = measurement are different then the conditions for full strung, and if = done full strung well the deed is already done so to speak... further = you pointed out then that you meant that there was no reliable way of = forcasting said changes. =20 OK. My previous answer was incomplete. But you're taking what I said out = of context. What I said was, "One of the problems I have with most of = the testing I have seen on the piano soundboard is that it was done on = an unloaded board and is, therefore, largely meaningless." This is some = different than you are implying above. It is my opinion that tests of = this type are basically meaningless unless they are done on soundboards = installed in a real world piano, strung and loaded. Remember, we're not = just trying to figure out the specific characteristics of the soundboard = alone, but the entire, interactive system. No where do I preclude the = possibility of obtain useable results from pianos that are strung and at = pitch. The reason they are not generally done this way is simple. It's very = difficult to do. You need full access to the soundboard and the plate is = in the way on the top while the belly bracing is in the way on the = bottom. Therefore to conduct a meaningful test something is going to = have to go. Since it won't be the plate it will have to be the belly = bracing. Before everyone panics, most pianos won't fly into a million = pieces if the belly braces are removed. But it will be difficult and = expensive. Hence, it's not done. > Hmmm.. In the section of the Wogram article entitled "Influence of=20 > string tension" He seems to be saying that the condition of an = uloaded > soundboard is not a problem. He says that the basic impedance = curve > and sound radiation curves remain basically the same and that = only the > lowest resonances are effected and that the effect is = predictable=20 > enough to take into consideration.=20 > Is this outdated ??=20 I don't know if it is outdated or not. I disagreed with Mr Wogram's = position on this when I first read that article and I still do. My = experience is different than his. I don't know enough of the details of = his work to have even the vaguest notion of what all might be different. I consider modal analysis of the working soundboard to be a good first = step.=20 You know, like, "one small step for man...."=20 Del I still believe this. It's not going to be the final word, but it can = certainly help us along the way. Stephen Birkett wrote: >=20 > I have my opinions about modal analysis (mentioned here once a=20 > while back)...that, at best, it can tell you that the soundboard is=20 > working as you already know that it is supposed to work. As a = practical=20 > tool for design I have my doubts it will ever give anything, = primarily=20 > because it treats the sb unloaded and in isolation from the = interactions=20 > with the rest of the piano. Well, as I said. In my opinion the soundboard must be loaded with real = world strings. None of the published tests I have seen so far have been = done this way. Del ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/50/9f/a0/99/attachment.htm ---------------------- multipart/alternative attachment--
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