Yikes! You must have raised the pitch of one or two pianos! What a perfectly complete and accurate explanation! Except the Verituner. It does not use any averaging for past notes. It measures the flatness of each note and directly calculates the user-designated overpull for that note based only on the flatness of that one note. I wish that it was able to incorporate info from other notes. But I do not find that a problem in use. I just mentally massage the indicated overpulls as I go, much like I used to do with my SATs. Terry Farrell ----- Original Message ----- From: "Robert Scott" <rscott@wwnet.net> To: <pianotech@ptg.org> Sent: Thursday, August 22, 2002 6:57 AM Subject: Pitch Raises ... Overpull Percentage > Conrad Hoffsommer asks: > > >For the benefit of newbies and non-ETD users, could you review just what > >that is 20%/25%/30% OF? > >I think I know, but I get confused ezee... > > The question is a good one. Different ETDs apply the 20%/25%/30% to > different things. I think the SAT applies the percentage to the flatness > of a single note. You can periodically measure a new note as you tune so > as to update what the percentage applies to, but it is still one > note. TuneLab and the RCT both measure every note before it is > tuned. They use running averages to determine the flatness of the region > of the piano where you are tuning, and apply the overpull percentage to > that running average. I think RCT uses what is sometimes called a "boxcar" > average, which is an ordinary average of the last few notes. TuneLab uses > a declining weight average to estimate the flatness of the piano where you > are tuning. A weighted average gives more weight to the more recent notes > and less and less weight to notes that are more distant from where you are > tuning, in order to form the average. In any case, however it is > determined, the overpull percentage is applied to the flatness of the > piano, and then the result is added on to the target pitch for the note you > are about to tune. For example, if the measurements say the piano (or the > region where you are tuning) is 40 cents flat, and the overpull percentage > is 25%, then the ETD will set a target pitch that is 10 cents higher than > normal, in anticipation of the pitch falling that 10 cents by the time you > finishing tuning the whole piano. > > -Robert Scott > Real-Time Specialties >
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