Mutator reviewed by Roger Brown

Is it a synth, is it an effects unit, is it a noise gate? The Mutator from Mutronics is none of these and all of the above. It's a stereo filter unit which has seen input during its development from sonic explorers such as Kris Weston of the Orb and David Toop, ambient artist par excellence. The end result of all this is a filter unit offering an array of sound processing functions normally associated with digital effects units.

 I first encountered the Mutator during an interview with David Toop. At first I couldn't understand his enthusiasm over what simply appeared to be the filter section of an analogue synth. Sure, analogue filters were great for processing sound from other sources but surely he could just run the signal through an old synth with an external input socket?

 Then he switched the Mutator on and proceeded to run a few simple patterns from his pedal stee1 guitar through it. The results were astounding, far beyond anything I'd ever heard before. I've experimented with running external signals, be they from a digital synth or "real" instrument, through just about every old synth and filter section I could find and I'd never come across the subtle colourings David was able to add to sound with his Mutator patched into the effects chain.

 My amazement was further increased upon receiving one of the first production models for review. David's Mutator was an early beta model and was mono, being one filter. The 2U rackmount unit I now had before me was stereo, comprising two filters which could be chained or run independently. Around the back were not only two input and two output audio jack sockets, but a pair of input sockets for an external CV and a pair of input sockets for an external trigger!

 Closer examination of the front of the unit and a little cursory perusal of the manual revealed another addition to the Mutator's abilities I hadn't even thought of. Feeding the output from the Mutator back into itself and feeding an external trigger into the Mutator turned the unit into a noise gate. The Mutator's other big secret is that it also incorporates two VCA's as well as two VCF's. With the two LFO's set to VCA instead of VCF, the Mutator becomes a stereo auto panner.

 Control is what the Mutator offers in abundance. The front panel is initially bewildering simply because the options available are, like modular synths, often difficult to fathom. The link switch between LFO one and channel two for instance offers an invert option. This inverts the phase of the signal from LFO one before it is sent to control channel two. This doesn't initially seem all that exciting but a little experimenting reveals that the invert setting is responsible for the auto panning effect. If applied to the Mutator's VCF's instead of its VCA's then stereo filter sweeping is the result. Truly, this is a unit which encourages you to explore the almost infinite combination of settings available. Every change offers a new avenue of sonic exploration.

 What you get are two LFO's running two VCF's and/or two VCA's. You can set either channel to VCA, VCF or a combination of both and link the two channels so channel one controls channel two or operate the two channels independently. The trigger control for each channel can be set to External or Internal independently, as can the switch between Gate or Envelope. Each LFO offers a choice of four waveforms and you have independent control over rate and depth. In linked mode only the depth control has any effect on channel two, channel one controlling its rate in that case. Independent control over each channel's Sensitivity, Attack and Decay, Envelope Sweep, Filter cut-off and Resonance is all there on the front panel with large black knobs just crying out, "turn me!"

 Beyond simply using an external signal to gate sounds you have the option of utilising that signal to trigger the envelope of either or both channels. Using a fast hi-hat pattern to trigger resonant VCF envelope on a slow pad patch produces a stunning variety of effects. Used simply as a filter section for turning digital sounds into analogue squelches the Mutator functions even better than you would expect, mutating a dry slap bass into a resonant Moog squelch faster than you can say 'LFO 1 to LFO 2'.

 Mutronics are obviously not content with the wondrous beast they have created and the upgrade to full MIDI control promised in the manual is alreadywinging its way to The Mix. Not to imply that the Mutator suffers for the lack of this digital option. The sheer beauty of this machine lies in its twiddlability. It's been patched into my desk for over two months now and I'm still discovering new sounds from it and new uses for the Mutator every day. Just send a sound into it and start flicking switches and turning knobs on the fittingly retro front panel and all manner of glorious sonic vibrations emerge from the desk. Just like a modular unit tbe Mutator can take'a musical phrase and completely alter it into an accompaniment to the original and is the most desirable piece of purely analogue kit I've come across since The Aviator graced the laboratory last year. Both these machines come with buckets full of that factor which makes analogue synths such fun. Kris Weston says it in his introduction to he delightlly tongue-in-cheek manual far better than I ever could, "Let us be stuck on page 23 of OSC 1 random modulation no longer – just turn the frigging knob!".
 Roger Brown


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