So for the A above middle C on a 60 Hz organ: (1200/60) * 16 * (88/64) = 440 Hz
</verbatim>
-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.
+This A tonewheel frequency
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 was
introduced in 1936 and
copied Hammond's use of an AC mains driven synchronous motor spinning
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 the
A of the Stroboconn (and the Hammond)
that the international concert pitch standard of A = 440 Hz
was established.
None of the twelve semitones on the Hammond are exactly equal tempered in their relationship to each other. 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) = 4440 Hz
</verbatim>
