Envelope Generators

Envelope Generators

Envelopes don't make noise themselves, but they do something even better: they give your sounds shape. They control how things move, swell, bloom, or vanish. They’re how you shape sound. And Spirit gives you two of them.

The Two Envelopes

Spirit includes two envelope generators:

• Filter Envelope – shapes the filter cutoff over time

• Loudness Envelope – controls overall signal level via the VCA

Both follow the classic ADSR structure:

• Attack – how fast it rises

• Decay – how fast it falls after the peak

• Sustain – the level it holds while the key is down

• Release – how long it takes to fade out after you let go

Filter Envelope

The Filter Envelope is always connected to the Upper Filter’s cutoff. It also affects the Lower Filter, but only when the Lower Filter’s Tracking switch is set to Dynamic (not Formant). That means you can sweep both filters together, or lock one in place for creative dual-filter effects.

Controls:

• ADSR Sliders – shape the timing of the envelope

• Velocity Slider (V) – sets how much key velocity affects the Filter Envelope. With higher values, playing keys with great velocity increases the effect of the envelope.

• AMOUNT – sets how strongly the envelope modulates the filter cutoff. Positive values create a normal, rising envelope. Negative values create a mirror-image of a normal envelope.

Use it for:

• Classic synth sweeps (slow Attack and Release stages)

• Percussive filter plucks (fast Attack, Decay, and Release stages)

• Long, evolving pads with filter motion (slow Attack, Decay and Release stages)

• Formant-style form shaping (specifically when paired with the Lower Filter in Formant mode)

Loudness Envelope

Thie Loudness Envelope controls the VCA (voltage-controlled amplifier) for the Filter/ADSR signal path. In other words, it shapes the volume of a sound over time.

Controls:

• ADSR Sliders – define the volume shape from attack to release

• Velocity Slider (V) – sets how much key velocity affects the Loudness Envelope. With higher values, playing keys with great velocity increases the effect of the envelope.

• AMOUNT – sets how strongly the envelope modulates the filter cutoff. Positive values create a rising envelope. Negative values create a mirror-image.

Use it for:

• Shaping dynamics and articulation

• Creating plucks, swells, stabs, fades, and pads

Not Just for Filter and Volume
Spirit’s envelopes are routable modulators in Matrix Z. Use them to:

• Modulate pulse width for evolving timbral changes

• Add pitch envelopes for divebombs or blips

• Modulate the speed of the Arpeggiator

• Modulate panning

Key Trigger Modes

While not technically part of the Envelope Generators, the Trigger switch determines how envelopes respond when you play overlapping notes, and it can subtly (or dramatically) change the feel of your performance.

In Single mode, the envelopes trigger only when the first key is pressed. As long as at least one note is held down, new notes won’t retrigger the envelopes, they’ll simply slip into the existing shape. This creates smooth, legato transitions between pitches, perfect for fluid leads, expressive glides, and sustained textures where you don’t want the sound to restart with every key.

In Multiple mode, every new note you press fires the envelopes from the top, even if you're still holding other keys. That means each note gets its own fresh attack and decay, giving you sharper articulation and more rhythmic precision.