Boss SL-20 Slicer Audio Pattern Processor
Originally printed in Guitar World, Holiday 2008
While many stomp box builders continue to concoct every conceivable variation of distortion, tremolo, wah, delay, chorus, flanger and pitch-shifting effects, the new frontier for exploration is sequenced effects. A distant and more highly evolved cousin of tremolo and gating, sequenced effects cut an input signal into individual parts over a specific interval of time while they apply controlled, but varying, processing to each part. The processing usually involves some sort of filtering, and the individual parts can be spaced out at regular, consistent intervals or arranged in rhythmic patterns.
The Boss SL-20 Slicer Audio Pattern Processor joins a growing selection of sequence-based effects like the AdrenaLinn III, Moogerfooger MuRF and the Z.Vex Seek Wah, Seek Trem and Ringtone pedals, but it also offers its own unique take on sequencing effects. While similar effects have been available for a while as software plug-ins and on keyboards and DJ mixers, the Boss SL-20 is packaged in Boss’s familiar twin-pedal format, which makes it a powerful but user-friendly effect for gigging guitarists.
The seven knobs, two buttons and 13 LEDs make the pedal look complicated, but its operation and functions are surprisingly simple. Individual direct- and effect-level controls let you dial in the perfect balance between your dry guitar sound and the processed signal. An output mode button lets you scroll through various output settings: Mono, Fixed Stereo, Random Panning, Ping-Pong, Auto (a smooth panning effect), 3D Cross and 3D Panner. Attack and duty knobs control the volume level of the processed signal’s attack and the duration of each sliced segment. Bank and pattern knobs offer 50 pattern variations to choose from, and the pedal mode switch lets you select Latch (normal on/off pedal) or Momentary (effect is on only when the pedal is held down) operation. The tempo knob adjusts the tempo from 30 to 250bpm, and it is surrounded by an alternating red/green LED that indicates quarter-note beats.
Jacks include stereo inputs and outputs, a MIDI input for syncing the SL-20 to an external MIDI clock source, such as a sequencer or drum machine, and an input for an optional expression pedal that you can use to control effect, direct or output levels or attack or duty settings. In addition to turning the effect on and off, the left-side footswitch also operates as a loop record on/off switch in Latch mode, allowing you to record loops up to 40 seconds long. The rightside footswitch is a tap-tempo pedal.
The SL-20 Slicer is an instant groove generator that should provide most guitarists with hours of creative inspiration. The 50 patterns range from straightforward eighth- and 16th-note patterns with subtle dynamic variations to complex polyrhythmic grooves that generate harmonic counter lines and riffs when you select one of the 20 harmonic settings. If you love jamming along with dotted-eighth-note delay patterns, the SL-20’s rhythmic patterns and loop recording capabilities offer even greater creative possibilities that will expand your songwriting horizons.
To engage the loop recording function, hold down the start/stop footswitch for two seconds until the record LED stays lit. You basically get one chance to get the loop right on the fly or else you have to start the process all over again. You cannot store a loop in advance and recall it at any time, and you can’t change the tempo of a loop once it’s recorded.
Although the Slicer sounds great in mono, it truly shines when you use the stereo outputs. The 3D effects create wonderful moody psychedelic textures that ambient guitarists will absolutely love. The effect sounds best when you place standard effects like distortion and compression in front of it and place time-based and modulation effects like reverb and phase shifting behind it in the signal chain.
THE BOTTOM LINE
The Boss SL-20 Slicer is not a novelty effect that you’ll use only occasionally but rather the type of effect that can inspire several albums worth of songs. It’s an obvious choice for ambient and experimental-minded guitarists, but it’s also a great effect for anyone who wants to add a strong, unique rhythmic element to their music.
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