c fork / a fork; Fork stability.

[John W. Peterson]

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