Mark, As you surmised, this problem has nothing to do with the piano, and everything to do with the air changing the string's temperatures. The best approach is to move the piano so that it is not in a drafty spot during tuning, then move it back when you are done. Make sure the studio owners are aware of the draftiness problem - you can demonstrate it for them using your tuning machine easily. Simple zero out the display, then 'huff' hot air on the strings while playing it - the display will begin to move right away. Well, at least it works well with my unusually large quantity of hot air ;-) This problem could possibly be solved by redirecting a heating vent, or getting air deflectors for one or two vents that are blowing on the piano. A blanket or cover draped over the piano could help during tunings, too. Don Mannino RPT -----Original Message----- From: caut-bounces@ptg.org [mailto:caut-bounces@ptg.org] On Behalf Of Mark Dierauf Sent: Wednesday, June 16, 2004 7:27 PM To: caut@ptg.org Subject: Yamaha C7 tuning instability 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 _______________________________________________ caut list info: https://www.moypiano.com/resources/#archives
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