My own explanation is basically, "I don't know," and I'm not ashamed to admit it. I suggest that soundboard movement is a factor, along with bridge movement, rim movement as well as the rest of the belly components. What I THINK I know is that variable humidity levels cause tuning instability and a quicker demise of any piano, and that controlling humidity goes a very, very long way toward minimizing these issues. We know that wood changes it's dimensions with changing RH. We also know that having a stable RH yields a vastly more stable instrument, but it's awful tough to quantify how much and exactly where in the system these changes are or are not happening. I tell my clients something of that nature as well. It's a pretty simple argument to make that controlling humidity is the key, it's a bit tougher to quantify "why." William R. Monroe On Fri, Apr 2, 2010 at 2:18 PM, <tnrwim at aol.com> wrote: > > Hi Wim, > > This may be the way we've been explaining it for eons, but this theory is > certainly in question. Read Ron N.'s article in the April 2006 Journal > which speaks directly to this. More, I believe it was Ric Brekne who wrote > an article some time back which addressed the concept of pitch change due to > soundboard crown increasing. When he isolated the one variable of rise and > fall of the soundboard, it was pretty quickly apparent that the amount of > soundboard rise required to affect a significant pitch change was absurdly > large. The math just doesn't support the theory that soundboard rise and > fall is responsible for major pitch changes. It is involved to be sure, but > is likely not even the major factor. Lot's to chew on, and I apologize in > advance if I've referenced the wrong author. > > William R. Monroe > > > For some reason, somehow, I missed these articles. As you say, it is a > theory and in no way am I going to debate this theory. But so that I can be > correct in what I have on my website, how would you describe what's going > on. in layman's terms. > > Wim > -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://ptg.org/pipermail/pianotech.php/attachments/20100402/7bb489c2/attachment.htm>
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