The "Echorus" is basically a very short echo on which is applied an optical vactrol based modulation. It creates a warm and organic chorus effect.
It can be used as a doubler effect to expand your sound dimension when "DEPTH" and "SPEED" controls are set at minimum.
For a regular gentle chorus tone, set the "D TIME" control at minimum, and the "DEPTH" around 11 o'clock. At longer delay time you'll get deeper modulation and more detuned sounds.
Flip the switch to kill the dry signal and get cool and warm "vibish" tones. You can also reach special alien effects at extreme setting.