A slicer is an effects unit which is similar to a tremolo, vibrato, phaser, or autopan.
It combines a modulation sequence with a noise gate or envelope filter to create a percussive and rhythmic effect like a helicopter, with rapid cutting out and coming in—on and off.
[1] Most have variable speeds and depths, creating different sounds.
The Boss SL-20 is an example of a slicer effect in a guitar pedal.
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