---------------------- multipart/alternative attachment In a message dated 6/16/04 9:27:49 PM Central Daylight Time, mark@nhpianos.com writes: I take care of an older Yamaha at a recording studio that has a tuning instability problem that I've never encountered on any other piano - the pitch fluctuates by as much as 3 or 4 cents over the course of only a few minutes. It took me quite a while to realize that this fluctuation ran in sync with the forced hot air heating system. Now that it's summer, the air-conditioning from the same vents is having the same effect. The piano has a complete DC unit installed with a bottom cover, is tuned at least 20x annually, and is very pitch-stable in the long term. It is not located in direct sunlight and the temperature doesn't vary much, certainly not within seasons. In the winter there is a humidity control system adding moisture through the hot air ducts. The studio is in an old New England barn that had several hundred thousand dollars worth of renovation, and so is very well finished and insulated, but in the time that it takes me to work through the temperament the first notes tuned have already moved substantially. Once after chasing the pitch all through a tuning I repeated A4 for several minutes and watched the pitch rise about 2 cents above the starting point then fall about 2 cents below. This cycle kept repeating as I watched. Has anyone ever seen such a problem? Did you find any solutions? - Mark Mark I would start by tightening as many plate screws/bolts as possible. Also, even though you might not hear it, check to make sure the soundboard is tight all around the edges. Wim ---------------------- multipart/alternative attachment An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/caut.php/attachments/c0/62/8f/3b/attachment.htm ---------------------- multipart/alternative attachment--
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