the chopper has a unique treadle design which allows a better utilization of space in order to accommodate the control functions in a compact foot - pedal sound effect . in the case of the chopper , the space is required to allow the multiple control functions required to achieve delay emulation , which is a new and unique sound effect generated by this product . the sound effect is controlled by means of a foot treadle that can uniquely control multiple parameters . the rate at which the foot treadle controls the effect is by means of a specific and unique optical coupling . to enable precise control of the effect , there is a visible read out of the modulation frequency which has not been achieved before in a foot pedal . further , the modulation frequency can be controlled by a midi sync code which is also unique in a foot - pedal format .