!!!Hammond Vibrato
(Excerpted from the OriginalHammondLeslieFaq.)
-Vibrato is the periodic ''raising'' and ''lowering'' of the pitch, and is thus fundamentally different from ''tremolo'' which is a variation in only the ''loudness'' of the pitch. The early Hammond organs featured a tremolo
system however it was generally considered to not be very effective. The Hammond vibrato was invented by Hammond engineer JohnHanert. This vibrato is implemented using a tapped DelayLine: really a ''low-pass filter''. The signal is applied to the DelayLine and a rotating [Scanner], attached to one end of the [ToneGenerator] assembly, picks the signal off of the DelayLine at the ''tap points''. The [Scanner], a single-pole 16-throw air-dielectric capacitor switch, is wired so that the tap point will traverse the entire delay line twice, once up the DelayLine and once back down, for each [Scanner] rotation. As the DelayLine is traversed ''phase'' is added-to and then subtracted-from the signal.
+Vibrato is the periodic ''raising'' and ''lowering'' of the pitch (frequency modulation)
, and is thus fundamentally different from ''tremolo'' which is a variation in only the ''loudness'' of the pitch (amplitude modulation)
. The early Hammond organs featured a [Tremolo]
system however it was generally considered to not be very effective. The Hammond vibrato was invented by Hammond engineer JohnHanert. This vibrato is implemented using a tapped DelayLine: really a ''low-pass filter''. The signal is applied to the DelayLine and a rotating [Scanner], attached to one end of the [ToneGenerator] assembly, picks the signal off of the DelayLine at the ''tap points''. The [Scanner], a single-pole 16-throw air-dielectric capacitor switch, is wired so that the tap point will traverse the entire delay line twice, once up the DelayLine and once back down, for each [Scanner] rotation. As the DelayLine is traversed ''phase'' is added-to and then subtracted-from the signal.
The chorus signal is produced by adding non-pitch-shifted signal to the pitch-shifted signal.
The three settings each of vibrato and chorus correspond to different amounts of total delay thus different amounts of total pitch shift.
