Mod X

Mod X

Mod X is one of Spirit’s two main modulation engines. Its purpose is to add motion, expression, and sometimes chaos to a sound. Whether you’re after classic vibrato, sample-and-hold weirdness, or something rhythmically complex and reactive, Mod X is where much of the action begins.

This section controls the shape, rate, source, and routing of the modulation signal controlled by the Mod X Wheel, which is routed to a destination set with the X Wheel Destination knob.

MOD SOURCE

Choose from six modulation types, each with its own character:

1. Triangle LFO – Smooth and cyclical. Good for vibrato, tremolo, or filter sweeps.

2. Square LFO – Instant up/down. Perfect for trills, on/off-like modulation, or rhythmic pulse effects.

3. S+H RANDOM – Sample-and-hold using red noise. Produces stepped voltages at a user-defined rate for glitchy or random modulation.

4. S+H Y – Sample-and-hold of the Shaper Y signal. This captures and holds segments of Shaper Y output, allowing complex, often unpredictable modulation shapes.

5. RED NOISE – Continuous, unfiltered noise. Use for intense, gritty modulation.

6. OSC B – Routes the triangle wave output from Oscillator B as a mod source. Useful for audio-rate modulation for FM (frequency modulation) and AM (amplitude modulation).

LFO / S+H RATE

Sets the rate of the modulation signal when using triangle, square, or sample-and-hold sources. Can go from ultra-slow to around 50 Hz. This control has no effect when using Red Noise or Osc B as the modulation source, since those are independent of the Mod X clock.

SHAPE X WITH Y

When enabled, the signal from Shaper Y is used to modulate the amplitude of the Mod X signal, essentially shaping how deep the modulation goes over time. It’s useful for creating “enveloped” vibrato, where the modulation depth grows or fades dynamically.

X WHEEL DESTINATION

Selects where the Mod X signal goes when you move the Mod X wheel (at the left of the keyboard). Destinations include:

• OFF (nowhere)

• OSC A + B pitch

• OSC A pitch

• OSC A RWM (rectangular wave width modulation)

• Filter cutoff (Upper + Lower or Upper only)

SYNC

Engage this switch to lock the Mod X LFO to the master tempo source (at the top of the plug-in window). Use this to create clock-synced modulation effects such as pulsing, tempo-synced filter sweeps, and S+H effects that stay in time.

RETRIG

When enabled, this retriggers the modulation waveform each time a note is played. It's useful for consistent attack behavior. When using Mod X for vibrato, for example, this ensures it always starts from the same phase.

Creative Applications

Sample-and-Hold Filter FX
Set MOD SOURCE to S+H RANDOM, RATE to mid or high, and route to Filter Cutoff. The result is a classic analog “burbling” filter effect that adds texture and motion to static sounds.

Enveloped Vibrato
Set MOD SOURCE to Triangle, SHAPE X WITH Y on, and use Shaper Y to create a slow, rising shape. Now when you modulate pitch with the Mod X wheel, you’ll get vibrato that blooms over time.

Audio-Rate FM
Set MOD SOURCE to OSC B and route Mod X to OSC A pitch. With Oscillator B in Wide mode, you can push into audio-rate frequency modulation territory for metallic, clangorous timbres.