Arturia MICROFREAK, Руководство пользователя

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8. THE LFO
An LFO (short for Low-Frequency Oscillator) can produce various waveforms at sub-audio
level. These waveforms can then be used to modulate other parts of the MicroFreak.
For example:
• the pitch of the Oscillator
• the cutoff frequency of the Filter
• the emphasis of the Filter
• the stages of an Envelope
A well-known application of LFO modulation is the filter sweep; the LFO waveform is used
to move/animate the cutoff point of a Low Pass Filter.
This is a good moment to understand what the other LFO waves do. Try switching to the
Triangle wave and the rising Saw wave; you'll hear how the sweep changes shape. The
Rectangle wave will cycle between a low and a high state, so it's not very useful for learning
about overtones. It can have its uses if you want to toggle an oscillator between two pitches.
Depending on the modulation amount you set on the Matrix it will make the pitch jump two
or four steps on the scale or, if you increase the amount of modulation even further, a full
octave.
8.1. LFO Shape
The Shape button allows you to choose one of six different waveforms: sine, triangle, rising
sawtooth, rectangle (square), random (sample & hold) and random gliding (or smoothed
random).
Note: The square wave has a 50% duty cycle, which is tech-talk for saying that it is on (high)
for 50% of the time.
The last two LFO waves are a special case. The Random wave does what its name implies: it
creates random modulations. You've probably heard this sound a thousand times before. In
early Sci-fi movies, this was that standard sound to accompany a futuristic computer with
many blinking lights. If you have an overwhelming urge to hear this, select the Random
wave on the LFO, set LFO speed to about 4.00 Hz and move the selection point on the Matrix
to the LFO>Pitch crossing. Press the Matrix knob and set the modulation amount to about
30. There it is!
The last wave of the LFO is a slewed random wave. Whereas in the first Random wave
the pitch changes abruptly from one pitch to another, here the changes are more gradual.
Again, to understand what this wave does it's a good idea to have it control the pitch of the
oscillator. It will probably result in an ugly wavering sound, but as a learning tool, nothing
beats it. This technique is a useful in-between step for any modulation you want to apply. It
enables you to fine-tune the modulation amount before applying it to a modulation target.
The MicroFreak LFO
49 Arturia - User Manual MicroFreak - The LFO