Modulation source → destination
Concept · First taught in PD3 Motion (Pad)
Patch cables on the back of an old synth — pick a source jack and a destination jack, and decide how much.
▸What it is
Modulation routing is the wire that connects a control signal to a parameter it changes. The source is something that generates a moving value — an LFO, a velocity reading, an envelope, the mod wheel — and the destination is any parameter that can be moved: filter cutoff, oscillator pitch, amplitude, pan. A routing has an amount knob that scales how much the source affects the destination, and the direction (positive or negative). Patching the same LFO to two different destinations creates compound motion; layering multiple sources on one destination lets the sound respond to several gestures at once. This is the architecture that lets a static patch feel alive.
▸Questions
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Can the same source modulate two things?
Yes. Routing one LFO to both filter cutoff and amplitude is common — the sound moves and breathes from the same gesture.
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What does a negative modulation amount do?
It inverts the source. If the LFO normally pushes the cutoff up, a negative amount makes it pull the cutoff down on the same cycle.
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My modulation is not doing anything — what is wrong?
Three common causes: the amount knob is at zero, the source is not running (LFO depth at zero, key not held for envelopes), or the destination is already at its limit.
▸In the curriculum
First taught
PD3 · Motion — Assign a slow LFO to the filter cutoff. Part of the Pad track.
Reused in
The same concept comes back in 1 lesson later in the curriculum, in a new context.
▸Related concepts
Concepts that share a lesson with modulation source → destination:
Hear what modulation source → destination does to a sound. The PatchPond studio runs in your browser — load a lesson patch and move the knob this concept controls.
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