Because there are nine switch contacts under each key and the key rotates through an arc, all nine switches _do not_ close simultaneously. They close somewhat sequentially (but not necessarily in the same order as the busbars are stacked). Which means if a key is "bounced" or "slipped" and not depressed to close all its switch contacts to their busbars, some harmonics may not be heard. In addition, the switches "bounce" a bit when the contacts close depending on the velocity that the key is pressed and this also affects the sound. These "defects" actually enhances the organic sound of a tonewheel Hammond. Most clonewheel Hammonds lack these "features" which is another reason they sound somewhat sterile. For a technical study of the Hammond key switching see _Dynamic Temporal Behaviour of the Keyboard Action on the Hammond Organ and its Perceptual Significance_ by Giulio Moro, Andrew P. Mc Pherson, and Mark B. Sandler in The Journal of the Acoustical Society of America, November 2017:
[https://asa.scitation.org/doi/pdf/10.1121/1.5003796https://asa.scitation.org/doi/pdf/10.1121/1.5003796]
-The pedalboards in
the console organs are similar but there are four busbars and each pedal closes _two_ switch contacts on each busbar. This "forces" a certain harmonic mix on the pedals that can't be altered as readily as the manuals. The four busbars are mixed by a fixed resistor network and harmonic levels are adjusted by just two drawbars. One drawbar adjusts the level of the Fundamental and 3rd Harmonic and the other adjusts the level of the remaining harmonics (even harmonics, 2nd through 12th). Note that the lowest octave of tonewheels on the console organs are not "hobbed" as sine waves but are more complexly shaped to add tonal color
to the pedals
.
+The pedalboards on
the console organs are similar but there are four busbars and each pedal closes _two_ switch contacts on each busbar. This "forces" a certain harmonic mix on the pedals that can't be altered as readily as the manuals. The four busbars are mixed by a fixed resistor network and harmonic levels are adjusted by just two drawbars. One drawbar adjusts the level of the Fundamental and 3rd Harmonic (basically odd harmonics)
and the other adjusts the level of the remaining harmonics (even harmonics, 2nd through 12th). Note that the lowest octave of tonewheels on the console organs are not "hobbed" as pure
sine waves but are more complexly shaped to add odd harmonics
to these tones. For a detailed description see patent 2,508,514
.
