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 William Being honest with a customer and admitting that you don't know why a piano goes out of tune is very respectable. But from a piano owner's point of view, that doesn't give much confidence. All the reasons you give are very technical. The one common denominator is the changes in humidity. The biggest part of the piano that is effected by the humidity is the soundboard. Humidity does something to the soundboard, that does something to the tuning. Yes, the other components are also effected, but the bridge doesn't rise and fall on its own, and the belly doesn't either. You are right that by controlling the humidity, it will stabilize the tuning. I see that here all the time. I've been here long enough to have done at least two tunings, and a lot of my pianos are dead on, and I have a hard time spending an hour on the piano. But the bottom line is that from a layman's point of view, the simplest answer is the easiest to explain to a customer. Wim -----Original Message----- From: William Monroe <bill at a440piano.net> To: pianotech at ptg.org Sent: Fri, Apr 2, 2010 9:40 am Subject: Re: [pianotech] Grey market pianos, seasoned pianos, etc. 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/ede0ec62/attachment-0001.htm>
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