
DR. REX LOOP PLAYER
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LFO Section
LFO stands for Low Frequency Oscillator. LFO:s are oscillators in the sense
that they generate a waveform and a frequency. However, there are two sig-
nificant differences compared to normal sound generating oscillators:
• LFOs only generate waveforms with low frequencies.
• The output of the two LFO:s are never actually heard. Instead they
are used for modulating various parameters.
The most typical application of an LFO is to modulate the pitch of a (sound
generating) oscillator or sample, to produce vibrato. In the Dr.Rex device,
you can also use the LFO to modulate the filter frequency or panning.
Waveform
LFO 1 allows you to select different waveforms for modulating parameters.
These are, from top to bottom:
Destination
The available LFO Destinations are as follows:
Rate
The Rate knob controls the LFO’s frequency. Turn clockwise for a faster
modulation rate.
Amount
This parameter determines to what degree the selected parameter destina-
tion will be affected by the LFO 1, i.e. the amount of vibrato, filter wah or
auto-panning.
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Waveform
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Description
Triangle This is a smooth waveform, suitable for normal vibrato.
Inverted
Sawtooth
This produces a “ramp up” cycle. If set to control pitch (fre-
quency), the pitch would sweep up to a set point (governed
by the Amount setting), after which the cycle immediately
starts over.
Sawtooth This produces a “ramp down” cycle, the same as above but
inverted.
Square This produces cycles that abruptly changes between two
values, usable for trills etc.
Random Produces random stepped modulation to the destination.
Some vintage analog synths called this feature “sample &
hold”.
Soft Random The same as above, but with smooth modulation.
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Destination
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Description
Osc Selecting this makes LFO control the pitch (frequency) of
the REX file.
Filter Selecting this makes the LFO control the filter frequency.
Pan Selecting this makes the LFO modulate the pan position of
the REX file, i.e. it will move the sound from left to right in
the stereo field.
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