From cervenka@earthlink.net Wed Nov 07 10:16:15 2007
Subject:Re: OT: Don Leslie's Finest Achievement?

Hi, I'm lucky enough to have a Rialto K among my instruments. I just
wanted to offer some info on the Isomonic vs. Space Generator systems
or features on these early Rialto/Leslie instruments.

The Rialto K separated the audio channels for the pure waveforms
(Tibia) from the complex waveforms (reeds, strings). It then further
split the complex waveforms into a "C" and a "C#" audio channel with
separate speakers. This additional split of the complex voices was
designed to prevent distortion caused by the electronic combination of
adjacent notes. It Isolated the Harmonics (Isomonic) and allowed
them to mix in the air rather than the electronics.

The Space Generator used in their Leslie speaker was a slow phase
shifting, motor driven type of a capacitor feature similar to the
chorus generators in a tonewheel Hammond.

If you search the patents you'll see that Don held the patent on the
Isomonic system.

It's about as far away from a clonewheel as you can get but it's got a
great old theatre organ sound :^)

Gary

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