Korg POLYSIX Owner's Manual page 5

3) PW/PWM
This controls the pulse width of the PW waveform, and the modulation depth of the PWM waveform (see
above).
4) PWM SPEED
This controls the speed of the modulation effect in the PWM waveform (see above). It has no effect on the PW
waveform.
5) SUB OSC
This switch allows you to add a second tune either one octave or two octaves below the VCO pitch. This is
useful for producing fatter and fuller sounds, particularly with solo or base Unison playing, organ sounds, and full
orchestra effects, etc.
While the waveform of both sub oscillator tones is a square wave, a phenomenon called "waveform
staircasing" causes the 1 octave sub tone to take on much of the timbral quality of the primary waveform. This
makes it sound like an octave "duplicate" of the main waveform. With a sawtooth as the main waveform, a very
full String Orchestra patch can be created using this principle, many other sounds can also be enhanced in this
fashion.
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