OCOOCOC is a wonderfully transparent and easy to use vactrol-based optical comp device (leveling amplifier). If you're after a crushing compression and really evident operation, definitely it's not the best choice. But if you value your actual tone and would like to gently improve it and add a few lbs to your sound body, enhance sustain or warm/sweeten attack up while preserving it's original quality and transients - OCOOCOC does this job exceptionally well.
Single compression parameter knob appearance provides ease of use and possibly most musical response for 'pedal-always-on' performance. With knobs set for minimal noticeable compression the pedal is set for 'unity gain'; increasing compression level yields in volume reduction, hence volume knob works as gain recovery with pretty big amount of output boost available (even with comp maxed). It handles low-end very well so it's great with both guitar ad bass, especially with ability to blend in uneffected signal in parallel with compressed signal.
NO BATTERY OPERATION POSSIBLE WITH THIS PEDAL. Feed it only with standard 9V DC negative center power supply.
VOLUME - output boost level
BLEND - turn CW to increase clean (uneffected) signal
COMP - turn CW to increase amount of compression
true bypass / buffered bypass switch