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Table Of Contents
Chapter 20 ES2 233
The LFOs
LFO is the abbreviated form of Low Frequency Oscillator. In an analog synthesizer, LFOs
deliver modulation signals below the audio frequency range—in the bandwidth that
falls between 0.1 and 20 Hz, and sometimes as high as 50 Hz. LFOs serve as modulation
sources for periodic, cyclic modulation effects. If you slightly modulate the pitch of an
audio oscillator at a rate (speed, LFO frequency) of, say, 3–8 Hz, you’ll hear a vibrato. If
you modulate the cutoff frequency of a lowpass filter, you’ll hear a wah wah effect, and
modulating the dynamic stage results in a tremolo.
The ES2 features two LFOs, the outputs of which are available as sources in the Router.
 LFO 1 is polyphonic, which means that if used for any modulation of multiple voices,
they will not be phase-locked. Furthermore, LFO 1 is key-synced: Each time you hit a
key, the LFO 1 of this voice is started from zero. To explain, when used on polyphonic
input (a chord played on the keyboard) the modulation is independent for each
voice (note). Where the pitch of one voice may rise, the pitch of another voice might
fall and the pitch of a third voice may reach its minimum value.
 LFO 2 is monophonic, which means, that the pitch of all voices will rise and fall
synchronously, if you modulated the Pitch123 target with the LFO2 source, for
example.
Both LFOs feature a number of waveforms. LFO 1 can fade in or out automatically,
without the need to engage a separate envelope generator. The LFO parameters are
detailed below: