The Echorec is based on a four playback head delay design. It's simple to create syncopated delays, swirling echoes, and arpeggiated slapbacks. The ability to turn trails on or off are just one of the convenient features on this pedal. With the program select knob, you can choose from 12 different playback head configurations. This allows you to have tons of variability in your delays. There are two internal trimpots that can be adjusted to change the gain or modulation characteristics.