Envelopes & LFO

An envelope shapes how a sound changes over time, in loudness, in brightness or both. Much of what makes an instrument recognisable is here: an organ jumps straight to full volume and stops almost at once, while a string section swells in and fades away. The MicroFreak’s envelope always drives the filter cutoff, shapes the volume when AMP MOD is lit, and can be patched to any destination in the The matrix.

An envelope does nothing until something starts it. A trigger is a very short pulse; a gate lasts as long as the note, anything from a few milliseconds to several seconds. Touch a key and hold it, and the gate starts the Attack. The envelope then moves through Decay to the Sustain level and stays there while you hold. Let go and the level falls to zero at the Decay/Release rate. There’s more on this in Gates and triggers.

Strictly, it’s an ADS envelope: Decay and Release share one knob, and Sustain lasts for as long as the key is held.

With AMP MOD unlit, gates from the keyboard and sequencer open and close the VCA directly, so a note starts the instant you touch a key and stops the instant you lift off. It’s a blunt, organ-like on/off. Press AMP MOD so it lights and the envelope uses those same gates to shape the volume, so Attack, Decay/Release and Sustain now apply to loudness as well.

The cycling envelope is a general-purpose modulation source. Like any envelope it can run through its stages once, but it can also restart itself when it finishes. That turns it into an LFO whose wave shape you draw with the knobs, including shapes a normal LFO can’t produce. You can also bend the curves of its Rise and Fall stages.

In Run and Loop, Rise is still the attack, but Hold keeps the level up for the length of time set by HOLD/SUSTAIN before the Fall begins.

To bend a stage, hold SHIFT and turn RISE or FALL. Turning left makes the curve more logarithmic: quick to get going, slow to finish. Turning right makes it more exponential: slow to start, speeding up towards the end. In the middle is a dead zone where the curve is a straight line, and the display shows LINEAR.

Utility > Preset > Envelope Legato sets what both envelopes do when you play legato, overlapping each new note with the last. OFF restarts them with every new note. ON lets only the first key start them, and later notes follow that first contour. It only applies when you play monophonically (Utility: preset settings).

The cycling envelope gets really interesting once its own knobs are under modulation. In the The matrix, route the LFO or keyboard pressure to Rise, Hold or Fall and the shape changes as you play. Pressure in particular gives you hands-on control of the Rise and Fall.

AMOUNT is an attenuator: it scales how hard the cycling envelope hits its destinations. Getting it right matters most on the analogue filter, where a little too much or too little can make the difference between an ordinary sound and a great one.

Try pointing the cycling envelope at the main envelope. On Attack it changes the attack slope; on Decay it changes how long the envelope lasts. From there you can build longer chains of modulation in the matrix.

The LFO, or low-frequency oscillator, produces waveforms below the audio range to modulate other parts of the MicroFreak: oscillator pitch, filter cutoff and emphasis, envelope stages and more. The best-known use is the filter sweep, where the LFO moves a low-pass filter’s cutoff up and down.

By default the LFO runs free, ignoring the MicroFreak’s tempo, and the display shows its rate in Hz. Press LFO RATE to sync it to the active clock, whether that’s the MicroFreak’s own, your DAW’s or an external MIDI source (Clock and sync). The rate then shows as a division: 8/1 (slowest), 4/1, 2/1, 1/1, 1/2, 1/2t, 1/4, 1/4t, 1/8, 1/8t, 1/16, 1/16t and 1/32. At 1/4 one LFO cycle lasts a quarter note; each step up roughly doubles the speed, and the t values are triplets.

To restart the LFO on every key press or sequencer gate, for a little pitch bump at the start of each note for instance, set Utility > Preset > LFO Retrig to ON. The setting also has a Legato option that skips the restart when you play legato (Utility: preset settings).