Phaser

ATMOSYNTH built-in module

Four allpass filters in a row, all sweeping together, added back to the sound they came from. Where the two disagree they cancel, so notches move up and down the spectrum — the sweep you hear is those notches, not the filter. Centre is where the sweep sits and Depth how far either side of it, in cents, so the sweep is even to the ear at any centre and cannot be driven below nothing. Dry and Wet are a half each: equal parts cancel completely, which is what makes the notches deep, and the two together never come to more than what came in. Rate is an input as well as a knob. There is no resonance control, because returning the last stage to the first is a feedback loop with no delay in it, which the module rules refuse and Web Audio cannot run.

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