ammoon AP-04 Tremolo Guitar Effect Pedal True Bypass Use the photoelectric tube circuit, same as the tremolo of the old electronic tube amplifier. Intensity and Rate knobs make it easy to adjust the tone and vibe.Intensity: adjust the mixing ratio of delaying signal & original signal; Rate: control and adjust the speed. True bypass design minimizes tone loss. LED indicates working and power statement. Achieves the distinctive sound heard on so many classic recordings.