Warm Audio have made plenty of headlines recently by sailing very close to the wind in terms of copying not just the sound but the look of some iconic pedals – the recent ODD Box being perhaps the most controversial. It should come as no surprise then that the Mutation Phasor II is a recreation of the Musitronics Mu-Tron Phasor II – a classic pedal favoured by artists such as Smashing Pumpkins, Robin Trower, and Parliament Funkadelic to name but a few.

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Now, Warm Audio has sought to dampen the furore around its pedals by claiming that they focus on creating faithful replicas of gear that is out of production or so expensive that most people won’t ever get the chance to play them. That’s… sort-of true with the Phasor II – Musitronics don’t make an exact replica of the classic 70s pedal, but they do produce the Phasor III, which combines the II and the Bi-Phase in one unit.

Quite how close to the bone that is, ethically, is a matter for you to decide – what we can’t argue with is the price, which is half the cost of a Mu-Tron III and barely a quarter of what an original unit will cost you.

As has been the case with all the Warm Audio pedals we’ve tried, the unit is well put together in a solidly constructed heavy duty aluminium casing. It’s not identical to the 70s unit either – it’s slimmer and shorter in what is probably a sensible nod to modern pedalboard convenience. That said, this unit is in no way small – you’ll be thankful for the top-mounted input and output jack sockets to save space on your board. A 9-volt DC centre negative power input socket helps keeps things simple in the juice department although there is no option to use batteries. A quick look inside the casing reveals well put together high-quality components.

In use

Distinctly different from the psychedelic swirling of the perhaps more widely known MXR Phase 90, the mutation phasor II occupies an altogether funkier sonic territory. The pedal utilises the three typical modulation parameters – Rate, Depth and Feedback. With a clean sound and the Rate control set low I was transported straight to world of Fool to Cry style R&B balladry – just resist the temptation to croon along in a Mick Jagger style falsetto! Dialling the ‘Rate’ up we move into more synth like guitar tones reminiscent of Stadium Arcadium-era John Frusciante. ‘Depth’ adds richness to the tone and ‘Feedback’ introduces the throaty, vocal like qualities that make this unit unique. Increase the latter and the circuit a begins to ‘speak’ albeit in a rather ‘jivey’ and indecipherable manner. No bad thing.

There is plenty of room for experimentation, but the results can easily become ‘unmusical’. However, with a little judicious tinkering with the controls you can easily recreate create a range of very pleasing 70s era Mu-tron like tones. Turning up the gain adds equally intriguing colorations to a distorted sound without ever getting mushy. The unit is also pleasingly quiet.

If you’re in the market for a conventional phaser pedal to recreate those Crazy Diamond or Van Halen moments, then this is probably not going to get you there. But that’s not really the point. There are some truly creative options on offer here and opportunities to produce original and distinctive guitar tones and textures. The vocal like quality afforded by the feedback control makes for some very interesting sonic experiments. The ability to combine all these sounds with distortion only bolsters this pedal’s versatility.

If you’re looking for a faithful clone of the original Mu-Tron without paying the inflated price for a vintage original, then this pedal is definitely worth a closer look.

Like this? Try these

• Musitronics Mu-Tron III ($299)
• MXR ’74 Vintage Phase 90 (£159)
• Orange Phaser (£199)