"This item has been bench tested and is in good working order. All used items come with a 90 Day Warranty."
The tremolo effect is achieved by varying the volume of the original sound cyclically to create a pulsating speaker effect. The PN-2 has a Rate and Depth control in addition to a 4-way Mode switch giving you the options of Pan-sawtooth, Pan-square, Tremolo-sawtooth or Tremolo-square wave. There is an LED light that blinks along with the tempo of the oscillator, so it is easier to dial in rhythmic tremolo in a low light situation.