fwiw: Temperament stretch: I checked the tuning file that I saved in TunelabPro for a recently tuned Yamaha G1. For this particular tuning in ET, with A4=440 as reference, C5 is +.45 cent. Fork stability: About 22 years ago, when I was tuning in the mountains of southwestern Va. and northwestern NC, I ran into serious problems trying to use a standard tuning fork. It was not uncommon to travel to a customer's house in -10F to +10F outdoor temperatures, and try to tune at 85-90F in the house. The exact figures are long gone, but I recall changes of at least 10 to 15 cents. Even after everything "stabilized" in the house, I was still experiencing 2 to 5 cent changes of the fork while trying to set A4. I tried a few different forks, including a heavy C fork. Same problem. I was able to solve my reference pitch dilemma by purchasing a Hale 'Electro Fork" from Tuner's Supply. It was amazingly stable from 0F to at least 100F and easily solved the problem. It still serves me well; In all these years, it has drifted from the original deviation of A4 -.09 cent (as stated on it's calibration certificate) to a recently measured A4 -.19 cent. (using TunelabPro calibrated to NIST). I am also aware that not all of the notes on the Electro Fork are as accurate as the A4. It just so happens that A4 is the only reference that I use with regularity as a pitch reference, so I have monitored that one note carefully. Regards, John Peterson Raleigh, NC
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