My God, if the accu-tuner isn't exactly on pitch all the time, what can we believe in? Really folks, when we are dealing with tenths of a cent, we really ARE splitting hairs. I checked one of our "concert" techs ( of which I are one, but it was the other guy, ) forks recently, he had no way of calibrating it,,, and it was four cents sharp! I admit, that's not a bad pitch, since the piano can drop from 441 to 440 when you're pounding in unisons; but I like to pound them in to the fork. At least then I know that my A is rock solid. (After I've done a pitch raise, and fidgeted around for an extra half-hour). This is only on pianos that are expected to be "pounded" in concert after I'm done. I only do "firm" test blows on in-home instruments. HHHHHHHMMMMMMMMm....... another topic for discussion? Kevin E. Ramsey ramsey@extremezone.com ----- Original Message ----- From: "Robert Scott" <rscott@wwnet.net> To: <pianotech@ptg.org> Sent: Saturday, January 20, 2001 3:16 PM Subject: Re: Calibration of ETDs > Kevin E. Ramsey wrote: > > > When I first got my SAT, I calibrated my forks to be at exactly 440 when > >at body temperature. I achieve this by tucking it between by belt and my > >body for about two minutes. I still have one of those forks in a drawer in > >my dresser, as a back-up. I check it once in a blue moon. It hasn't changed > >by a tenth of a cent in eight years, according to my SAT, so I kinda get the > >impression that the SAT isn't changing either. > > Yes, as long as your fork is not dented or bent and is kept clean and > used a the same temperature, it will be quite good as a standard. > Some tests that I performed recently on a medium-grade fork showed > that it takes 7.5 degrees Fahrenheit temperature change to make the > fork change 1 cent. So if you want .1 cent accuracy in a fork you > would need .75 degree temperature control. > > > I was under the impression that the SAT uses a quartz crystal, which can > >only oscillate at one frequency. Let me know if you think I'm wrong. > > A quartz crystal ocsillator can change its frequency with changes > in temperature, battery voltage, etc., although it does not change > nearly as much as a fork. And I am sure that the SAT incorporates > all the best voltage regulation and temperature compensation techniques > to achieve stability. But things can go wrong, so it's good to be able > to do a check-up once in a while. > > -Robert Scott > Ypsilanti, Michigan > >
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