I do many many many pitch raises -- almost every piano I tune, for the last 27 years. (Almost everybody lets them go too long.) I've found that the ideal average overpull is halfway between 1/3 to 1/2 the amount sharp as it was flat. In other words, a 41% overpull of the amount it was flat. For an easy-figuring example, say the piano is 18 cents flat. Half of that is 9 cents and a third of that is 6 cents. Half-way between 6 and 9 is 7.5, so I pull it 7.5 cents sharp, and almost invariably A4 ends up right on 440 Hz, or very close. However, if the piano is a half-step flat, I don't pull it 41 cents sharp. That would be too much. There's some degree of flatness where the usually-ideal 41% overpull has to taper off. For a half-step pitch raise, I usually overpull so that A4 is beating about 5 beats sharp. That's approximately 20 cents, I believe. Sometimes more is required, sometimes less. It varies. That's here in Denver -- probably different elsewhere. But what I often experience is: even though after the pitch raise, A4 is at 440; after I've gone through the fine tuning and pulled in unisons, when I go back to do the final check and touch up anything that has slipped, I find that the whole middle section is sharp! Why? --David Nereson, RPT -------------- next part -------------- An HTML attachment was scrubbed... URL: https://www.moypiano.com/ptg/pianotech.php/attachments/20060707/4f1bea65/attachment.html
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