Fishman AFX AcoustiVerb Mini Acoustic Guitar Reverb PedalThree quality reverbs Hall, Plate, Spring are blended in parallel with your direct sound while preserving your acoustic tone. The Reverb Time knob controls how long you hear the effect, and ranges from short to very large spaces. Tone knob affects only the reverb and not your direct sound. Similarly, the Level knob adds the effect into your signal chain without overwhelming the sound of your instrument.