YOU MAY REMEMBER we had a probe of the Mutronics Mutator about a year ago. Even if you don't, then with any luck you'll have seen it rewarded an honorary mention in last month's review of the Sherman Filterbank and Waldorf Miniworks 4-pole. Still in the dark? OK, the Mutator is a two-channel envelope follower and filter bank, revered by those who know its true power. Fact: Daft Punk wouldn't have given us the awesome Musique (AA side of unlikely chart-stormer DaFunk) and other Homework tracks without it. Last year, MIDI was a retro-fit on the Mutator but now you can buy it with a Kenton board fitted, so FM thought it was time to reassess this most curious of beasts. Anyway, with such an aggressive and intriguing name, how could we leave it out of this feature?
First thing you notice is that it could be too big for your rack! The unit's top plate has a lip on each side, making the Mutator slightly wider than your normal 19-incher. But what actually is the Mutator?
In essence, it's two separate external filters, each with its own envelope sweep (or modulation), cut-off and resonance control. The resonance is as biting as any analogue synth. Each filter has its own envelope follower, which can affect the filter response in two different ways: it can either analyse the incoming signal, and map its contour to the cut-off level; or use the envelope of a second, external signal, to do the same. There's a switch to toggle between your choice. There's also an LFO with four waveforms, and a depth amount, for each filter, which also plays around with the behaviour of the filter. It's good to see straight bypass switches, so you can instantly compare the mutated signal with the clean one. Bypass switches were missing on both the Sherman and the Waldorf. Another couple of switches alter the configuration of the LFOs, so they work independently or together, for stereo panning trickery .
The magic that MIDI does
Good as it stands, the Mutator really sparkles when MIDI enters the equation. There's a dedicated knob round the back not the best place for it, but no doubt the most practical which needs to be set to the base channel for filter I (so filter 2 responds to MIDI messages on the next channel up). The MIDI implementation is a cinch to use, which makes a refreshing change. With the filter in Env mode (not in Gate mode, as the manual says) the MIDI note number controls the cut-off frequency. No controllers, no mucking around with event editors, just play the keyboard and quantize for pinpoint filter accuracy (though I did wish for MIDI control of Env sweep). On the demo, the sample and hold effects on the drum loop were achieved with random 16th notes and severe quantize. Alternatively, you can achieve smooth cut-off changes with the pitchbend.
The LFO can also be retriggered using short MIDI pulses: these have to be played from a suitably high note if you don't want to shut down the cut-off. It's an unusual system: MIDI only retriggers the LFO, it's not a clock sync and you have to set depth and approximate rate to create sync effects. It's a great pity LFO depth wasn't MIDI controllable here.
The Mutator is chunky and made to be handled roughly. No poxy knobs-and-button machine this! The MIDI implementation is slim, but what's there is adequate. It doesn't need patch memories, as tone controls are so straightforward. It's not as programmable as the Waldorf, but that also means it's not as fiddly. It won't give you the dirty harmonics of the Sherman Filterbank either, but it's a bloody sight easier to house-train. Like the others, the Mutator will impart warmth and character to anything you pass through it. The price is daunting, but you're getting two filters here, as well as something a little bit special: this is the Bentley (not quite the Rolls- Royce) of filters, and you wouldn't expect to pick one of those up for a song. Just look what its done for Daft Punk, and they're not, er, daft... fM