Filter

ATMOSYNTH built-in module

Removes part of the sound: low-pass keeps what is below the cutoff, high-pass what is above, band-pass what is around it. Slope is how sharply — at nothing one stage, twelve decibels an octave, and at one a second identical stage doubles it, which is the steeper slope the Oberheims and Junos are known for. The cutoff is an input as well as a knob — an envelope patched into Cutoff opens the filter as a note starts, an LFO sweeps it — and Cutoff amount is how far, in cents, so the sweep is even to the ear wherever the cutoff sits. Below nothing that amount runs the other way: the same envelope closes the filter as the note starts instead, which is the polarity switch those instruments put beside theirs. Key tracking moves the cutoff with the note played, at one rising with the pitch, so a phrase keeps its brightness as it climbs rather than going dull at the top — it needs the note routed here as well as to the oscillator. Shelf gain is for the three shapes that lift or cut a region rather than remove it, low-shelf, high-shelf and peaking, and does nothing to the others; at the steeper slope it applies twice, as everything here does.

What this module is made of is not shown here. Fork it into the editor to see for yourself.