Future Retro XS - Manual (Page 18)

ANALOG CONTROLS
LOW FREQUENCY OSCILLATOR
A low frequency oscillator (LFO), is a modulation source whose frequency is generally below the range
of human hearing. The LFO provides multiple waveshapes and a variable rate at which it can modify
other parameters of a synthesizer. Common uses would be to add vibrato or tremolo to a sound, or to
create slowly evolving sweeps or changes to parameter settings.
WAVE: This control selects one of four waveforms for the LFO, including triangle, sawtooth, square,
and random shapes.
The TRIANGLE waveform provides a smooth linear rising/falling waveform, which is ideal for vibrato
and tremolo effects.
The SAWTOOTH waveform provides a smooth linear falling waveform with a quickly rising edge. The
effect of this waveform is similar to a decaying envelope with a fast attack.
The SQUARE waveform has only two possible states: high or low. This may be useful for creating trill
effects. In addition, the square waveform may also be used as a logical gate signal for triggering other
circuits such as envelope generators, analog sequencers, or arpeggiators.
The RANDOM waveform will produce varying amplitudes of voltages at a rate which is once per every
period of the other LFO waveshapes. This is useful when you wish to create sounds which are rather
unpredictable, having parameters jump around to various settings.
RATE: The RATE control determines the frequency at which the LFO will produce its waveform.
This control has two different modes of operation that are determined by the LFO SYNC switch.
When the LFO SYNC switch is in the OFF position, the LFO will be free running at variable rates from
4 seconds to 18 Hz. Rotate this control counter-clockwise for slower LFO rates, and clockwise for faster
LFO rates. The LFO LED will flash on and off at the rate of oscillation.
When the LFO SYNC switch is in the ON position, the LFO will generate its waveform at defined
divisions of a MIDI clock. There are 16 MIDI clock divisions in all, including 8 bars, 4 bars, 2 bars, 1
bar, 1/2, 3/8, 1/3, 1/4, 3/16, 1/6, 1/8, 3/32, 1/12, 1/16, 1/24, and 1/32 notes divisions.
In order to use the LFO MIDI SYNC function, make sure you have a MIDI sequencer or other MIDI
clock source’s MIDI OUT connected to the MIDI IN jack of the XS. You’ll need to set up your MIDI
sequencer to send MIDI clock/start/stop messages. When you first set the LFO SYNC switch to ON,
your sequencer needs to send a MIDI start command in order for the LFO to start syncing. Adjusting the
LFO’s rate while the LFO is syncing can cause the LFO waveform to become out of phase. To resync
the phase of the LFO waveform, simply send a new MIDI start message from your sequencer.
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