Hammond Skx PRO, Reference Manual, Page: 207 / 754

187
ORGAN Voice Section
u LESLIE®
Your Hammond SKX PRO has a built-in digital Leslie effect that replicates the sound of a twin-rotor Leslie
Speaker cabinet. In addition, the SKX PRO can also be used with a variety of different Leslie Speaker
cabinets.
t What Is A “Leslie Speaker?”
When the Hammond Organ was first introduced in the mid 30's, it was not “self-contained” - in other
words, the sound-producing apparatus was not contained within the console. In order to hear the sounds
produced by the organ’s tone generators, a separate “tone cabinet” containing an amplifier and speaker
system had to be connected to the organ console via a special cable. The Hammond Organ Company for
many years manufactured many different models of tone cabinets specifically for use with Hammond
Organs. The best known of these is probably the PR-40 model, which used a 40-watt tube amplifier to
drive a set of speakers.
Hammond PR-20, PR-40 Tone Cabinet A typical Leslie Speaker cabinet.
The Hammond engineers had very definite ideas about what a Hammond Organ should sound like and
the Hammond speakers were designed to deliver that sound. In the late 30's, however, an independent
engineer and organ enthusiast named Donald J. Leslie wanted a sound from a Hammond Organ more
nearly approximating the sound of a theatre organ, particularly a realistic theatre organ tremulant. He
found that rotating a baffle in front of a stationary speaker created the effect of a tremulant (the well-
known “Doppler effect”) and called the subsequent speaker the “Vibratone.” (The “Vibratone” designation
was eventually dropped and subsequent models would be known simply as Leslie Speakers.) Over a
hundred models of Leslie Speakers have been made over the years; probably the best known being the
models 122, 142, 145 and 147, all of which have 40-watt vacuum-tube amplifiers. The122 and 147 are both
41" tall (see above photo), while the 142 and 145 are 33" tall. The 122 and 142 have the same electronics,
as do the 145 and 147.
Although the 122 and 147, as well as the 142 and 145, share identical cabinet designs, they are electrically
dissimilar - the 122/142 is designed specifically for use with a Hammond Organ whose preamplifier has
“GG” terminals (a “balanced” signal output), whereas the 147/145 has an “unbalanced” input more suitable
for use with self-contained organs - other brands as well as Hammond. Additionally, the 122 and 147 have
different high-frequency responses - the 122 rolls off the treble at 6K to reduce key click, while the 147
does so at 8K, resulting in a slightly brighter overall sound.
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SKX PRO Reference Guide