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50 Low Frequency Oscillators Dave Smith Instruments
Low Frequency Oscillators
The four LFOs are special-purpose oscillators that produce a frequency
that is typically below the range of human hearing (although these can
actually extend into the audio range if set to their maximum frequency).
The LFOs are typically used for periodic modulation such as vibrato
(periodic pitch modulation) and tremolo (periodic amplitude modula-
tion). They can also be used as modulation sources for any of the many
modulatable parameters in the Prophet X.
The LFOs produce a variety of waveshapes, including triangle, sawtooth,
reverse sawtooth, square, and random. Though most often used for low-
frequency modulation, the Prophet X LFOs can actually function at speeds
that extend into the audible range for extreme effects.
The Low Frequency Oscillators
Triangle and Random waves are bipolar. That is, their waveshape is posi-
tive for half of their cycle and negative for the other half. In the case of the
triangle 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 posi-
tive values. In the case of the square wave this makes it possible to generate
natural-sounding trills.