In the 1930’s Laurens Hammond utilized the technology of his time to create an
electronic organ that was much smaller and required much less attention than a
conventional pipe organ. His design was clearly successful, as people still plays
these organs today. However, it is our belief that his design principles can be
implemented more effectively using modern technology, resulting in a more compact,
and more reliable organ.
BASIC DESIGN FEATURES OF THE HAMMOND ORGAN Probably the most unique thing about the Hammond organ is the way in which it generates
it’s tones. Most electronic organs of this time period used electronic resonance circuits
to create their tones. In the Hammond the tones are produced through the use of 91 metal
wheels, each with teeth, that are spun at an exact frequency in close proximity of an
electromagnetic pickup.
The next prominent feature of the Hammond organ is the vibrato scanner. The frequency
modulation of the tones in this organ are also produced in a unique way. An LC phase-shift
delay line is utilized in conjunction with a rotary multi-plate capacitor to produce a
variable phase shift to the signal.
OUR DESIGN In our organ each of the frequencies are produced discretely, similar to Hammond’s
electro-mechanical tone generator, but we are using a 20 MHz clock and an array of
digital and analog electronics to produce them instead of a 60 Hz synchronous motor
and a mechanical marvel.
We are also using a multiplexer and a modified delay line to re-create the effect
of the rotary capacitor with authenticity.
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