9. History: The story behind the Electro 2 instruments
NORD ELECTRO 2 V2.0x
Page 52
Laurens Hammond retired at age 65 in 1960 and passed away in 1973. One year after his death, the fac-
tory stopped making tone wheel organs. From then on, the only organs that were produced had electric
circuits -- but that's another story.
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The rotating speaker effect in the Nord Electro 2 is a digital
emulation of the Leslie 122 speaker cabinet. Leslie cabinets are
stand-alone devices. Their preliminary design was to amplify
and add modulation effects -- i.e., chorus and tremolo -- to the
sound generated by an electric organ such as those made by the
Hammond Organ Company.
What's the story behind this famous accessory to the Ham-
mond organ? It goes back to 1937, when musician and inven-
tor Don Leslie bought a Hammond Model A. Don was
interested in finding a musical instrument that could sound
like a pipe organ, and he decided to buy the Hammond be-
cause he figured it sounded close enough. To save money, he
chose not to invest in an accompanying Hammond tone cabi-
net because he thought he could make his own speaker system.
However, he wasn't satisfied with the organ sound coming
from his first fixed-speaker design because the sound was too
static. He wanted to create some kind of motion in the organ
sound, much like the way the sound of a pipe organ moves
around a big church because the pipes themselves are spread
out across many large ranks - collections of pipes - that cover
the frequency range across an organ console's keyboard manu-
als and pedal board. For several years, Don experimented with
various combinations of speaker configurations and rotating
components, and in 1940 he completed his first version of the
rotating-speaker concept.
Here is a picture of the inside of the Hammond tone wheel box. It's the basic design
that elevated Hammond to the top of the organ manufacturer mountain. Each note
on the Hammond corresponds to a tone wheel. Every tone wheel has it own pick-
up comprising a magnet with a coil. The pitch of the sine wave generated by a tone
wheel is determined by the number of notches on the edge of the wheel and the
wheel's rotation speed. Every time a notch in the wheel passes the magnetic field, it
induces a voltage in the coil. The more notches and the faster they pass, the higher
the pitch.
Leslie 122 rotating-speaker cabinet.
A close-up view of the nice woodwork on a
Leslie 122 speaker cabinet.
