After the patent was issued and before production began, Hammond figured out a different combination of GearRatio''''s that would change the number of teeth at the Cs rather than at the Fs. To simplify production he kept one standard set of [Driving Gears|DrivingGear] and [Driven Gears|DrivenGear] for each octave.
He also figured out a way to generate a top half octave without 256 tooth tonewheels. The ratio of a perfect fourth to unison is 4:3 or 1.333 times higher. Since 256/192 is approximately equal to 1.333, Hammond cut the top tonewheels to 192 teeth and changed the gear ratio between the driving gears and the driven gears to that a perfect fourth above the desired pitch. In other words, the gear ratio for the upper C was the same as that used on the F tonewheels below it. Because 256/192 is not exactly 1.333, the upper seven pitches are slightly sharper than the other other octaves (another reason a tonewheel generator sounds different than most clones with perfectly divided digital octaves). Only seven tones could be produced using these gear ratios so most generators produce 91 tones. But, because of the way the tone generator was designed, the number of tonewheels in a generator had to be divisible by 12. So five blank tonewheels with no teeth (and no magnetic pickups) were used to keep everything running smoothly.
-These
early organs also
lacked foldback
in the lower octaves
.
+Because it was impossible to build a "single-toothed" tonewheel that could rotate without unbalancing the [Tone Generator|ToneGenerator] the lowest octave in the organ had no "subfundamental" tones and the key contacts were left disconnected. Thus, these
early organs lacked [HarmonicFoldback]
in the lower octave
.
!!! The 82 Frequency Generator
The folowing models were produced during World War II and have an 82 frequency generator:
