34 Low Frequency Oscillator
Dave Smith Instruments
Low Frequency Oscillator
The LFO is a special-purpose oscillator that produces a frequency below
the range of human hearing. The LFO is typically used for periodic
modulation such as vibrato (periodic pitch modulation) and tremolo
(periodic amplitude modulation).
The LFO on the OB-6 produces a variety of waveshapes, including sine,
sawtooth, reverse sawtooth, square, and random. Though most often used
for low-frequency modulation, the OB-6 LFO can actually function at speeds
that extend into the audible range for extreme effects.
LFO
VCO 1
VCO 2
PULSE WIDTH
AMP
FILTR FREQ FILTR MODE
INITIAL AMT
LFO SYNC
SHAPE
FREQUENCY
1
2
SAWTOOTH
SINE
REV SAW
RANDOM
SQUARE
The Low-Frequency Oscillator
Sine and Random waves are bipolar. That is, their waveshape is positive for
half of their cycle and negative for the other half. In the case of the sine
wave, this makes it possible to generate a natural-sounding vibrato that
goes alternately sharp and flat in equal amounts on either side of a center
frequency. Random, also known as “sample and hold,” generates a series
of random values, each held for the duration of one cycle
The square wave, sawtooth, and reverse sawtooth generate only positive
values. In the case of the square wave this makes it possible to generate natural-
sounding trills.
Summary of Contents for ob-6
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