So for the A above middle C on a 60 Hz organ: (1200/60) * 16 * (88/64) = 440 Hz
</verbatim>
-This A tonewheel being exactly
the same frequency as
the commonly accepted concert pitch standard of
440 Hz is not accidental but prescient
. Historically, concert A has wandered between 430-450 Hz. Beside the Hammond, the
famous Stroboconn tuner introduced in 1936 also used a
synchronous motor to spin a disc
that set concert
A at 440 Hz. Within a couple of years, Stroboconn tuners were being used globally to tune concert orchestras. By 1939 enough orchestras had set their concert pitch to A = 440 Hz that the international concert pitch standard was established. None of the twelve semitones on the Hammond are exactly equal tempered. The notes which are the farthest off pitch in the first seven octaves are the G#. They are .69 cents flat from the correct pitch. The top half octave is farther off pitch due to the number of teeth on the tonewheel not equaling 256. Using 192 teeth, generating the correct pitch from C7 to F#7 requires using the gear ratios for F through B. In the top half octave, the C# is the farthest off pitch, about 1.93 cents sharp:
+This A tonewheel being 440 Hz actually influenced
the establishment of
the commonly accepted concert pitch standard as
440 Hz. Historically, concert A has wandered between 430-450 Hz. The
famous Stroboconn tuner introduced in 1936 copied Hammond's use of an AC mains driven
synchronous motor to spin an optical disk
that also
set the
A above middle C
at 440 Hz. Within a couple of years, Stroboconn tuners were being used globally to help
tune concert orchestras. By 1939 enough orchestras had set their concert pitch to A = 440 Hz that the international concert pitch standard was established. None of the twelve semitones on the Hammond are exactly equal tempered. The notes which are the farthest off pitch in the first seven octaves are the G#. They are .69 cents flat from the correct pitch. The top half octave is farther off pitch due to the number of teeth on the tonewheel not equaling 256. Using 192 teeth, generating the correct pitch from C7 to F#7 requires using the gear ratios for F through B. In the top half octave, the C# is the farthest off pitch, about 1.93 cents sharp:
<verbatim>
For C#-4434: (1200/60) * 192 * (74/64) = 4440Hz
</verbatim>
