Rising from the smoke and flames of the MXR Custom Shop is the pedal of which every fuzz freak dreams. You never know when you’ll need that extra octave, so MXR has taken it upon themselves to enable gear-addicted guitarists yearning for belligerent tones. The result is the Sub Machine Octave Fuzz, which adds not just one octave, but two.

The Sub Machine is the younger, larger brother to the La Machine, MXR’s take on the Foxx Tone Machine. While the La Machine features an Octave Up button, the Sub Machine provides that as well as an Octave Down knob. You can mix the level of the sub-octave with fuzzy gain settings and run the octave signals in series or parallel via a Series button. These three sounds and the ability to mix them offer a broad selection of gnarly, large-bottomed fuzz-itude.

The Sub Machine is a solid pedal that features a Volume knob to control the level of fuzz and a Tone control to shape the overall EQ. The Fuzz knob works to manipulate the amount of gain or intensity, while the Sub knob controls the level of the sub-octave signal. The Sub Machine also comes equipped with a Bypass switch and is powered by a 9-volt battery or AC adapter. The tough purple casing and layout are eyecatching, too.

A good fuzz can run the gamut from ripped speaker to brain-slicing to Eric Johnson’s warm and cozy sonic brilliance. The Sub Machine is highly tweakable and allows the user to dial in anything from clean-dirty boost to traumatic pillage. While the fuzz sounds lean more toward truculence than the smooth blues-rock sounds dimed by Joe Bonamassa, it has a wide spectrum of upscale grittiness. It convincingly replicates supercharged aggression from the ’60s, including Jimi Hendrix’s incarnations.

The Sub-Octave is so addictive it could get you fired from your band. It could easily clear a room, as well. It’s beautifully nasty and subterranean, creating bowel-loosening low overtones, while the Octave Up feature adds cresting peaks of high-octave brilliance. In the right hands the MXR Sub Machine Octave Fuzz is a dangerous pedal that will inspire great riffs and live on pedal boards in perpetuity.

This article originally appeared in VG March 2016 issue. All copyrights are by the author and Vintage Guitar magazine. Unauthorized replication or use is strictly prohibited.