MusicRadar

The footswitches are using for setting tempo and turning the effect on/off.

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• Review

Back in the days when we used to record everything onto tape, there was an interesting little technique that involved feeding the key input of a hardware noise gate with a drum machine or another rhythmic pulse with the aim of triggering the gate and chopping up or slicing an audio signal into a rhythmic pattern.

Of course, in these digital days there are plenty of computer-based ways to achieve similar effects, but the latest product from Boss puts it into a most convenient hardware form.

The SL-20 Audio Pattern Processor, aka Slicer, is the latest in the Boss Twin pedal series and is designed to transform any played instrument or recorded track into a percussive chopped groove.

Overview

The Slicer has 50 different slice patterns onboard, including a Harmonic Slicer feature that generates percussive melodies. It's a stereo unit that offers various panning options and plenty of control over the characteristics of the generated pattern. Other features include loop recording, tap tempo and sync to external MIDI Clock.

An Effect Level knob as well as a Direct Level knob ensure that you can either have a fully-sliced sound or superimpose the sliced sound on top of the dry sound for a more subtle effect.

You also have practical control over the shape and size of each slice in a pattern via a pair of knobs. The Attack knob adjusts the pattern's attack while the Duty knob sets the duration from a small percussive segment to letting more of the original sound through.

The patterns themselves are in five banks of ten, selected by a pair of rotary switches. The overall tempo is also under knob control and is indicated by an illuminated ring around the knob that flashes red on every fourth beat and green on the others.

The largest features on the SL-20 are the twin footswitches. Although tempo can be set internally using the Tempo knob, the right footswitch is for tap tempo and can also be used to jump back to the beginning of a sliced pattern.

The left switch turns the effect on and off, but it can operate in two modes. In Latch mode, it turns the effect on and off with subsequent pushes. In momentary mode, the effect is active for as long as you keep your foot on the footswitch. The footswitches are also used in loop recording – up to 40 seconds of sound can be saved to the SL-20's memory.

Although it has full stereo in and stereo out if needed, the SL-20 can be used in standard mono in/mono out stompbox mode or can generate a stereo output from a mono source.

The full potential is unleashed in stereo, as there's a choice of six stereo output modes with different panning functions. You can have a fixed stereo position, the sound panning between left and right either smoothly or as a bounce, or random movement between right, left and centre. Two of the modes produce a 3D effect; one is a swirling panner while the other moves the sound forward and backward as well as left and right.