Marshall ShredMaster

The Marshall ShredMaster is a high-gain distortion pedal from Marshall, first launched in 1991 and designed to replicate the sound of a cranked Marshall JCM900 amp in a stompbox¹. It was Marshall's first-ever high-gain pedal and one of the earliest effects aimed squarely at metal and hard rock guitarists². The original run ended in 1998, when it was replaced by the Jackhammer, but Marshall brought it back in 2023 as the Shredmaster Vintage Reissue, rebuilt component by component and hand-built at the company's Bletchley factory³⁴.

For a player, the ShredMaster delivers what Guitar.com called "the metal-ready JCM roar"⁵: a distortion voice with a scooped-midrange option through its Contour control, and enough range in the gain knob to cover everything from near-clean boost to full high-gain rock¹. It is also the pedal behind one of the 1990s' most recognizable guitar tones, used by Jonny Greenwood on Radiohead's Creep⁶.

A cranked JCM900 in a pedal

The original ShredMaster was conceived as an amp-in-a-box pedal before the term was common. Guitar.com's review puts its purpose plainly: it "was intended to replicate the sound of a cranked Marshall JCM900"¹. MusicRadar likewise describes it as a distortion based on the JCM 900⁶. Marshall itself calls the original its first-ever high-gain pedal, one that "has become synonymous with game-changing music throughout the 90s and beyond"².

Within Marshall's own pedal history, the ShredMaster sat at the top of the gain ladder. Gearnews characterizes the 2023 reissue lineup as a low-gain Blues Breaker, a mid-gain Drivemaster, and a heavier-gain Shredmaster, "though not by today's standards"⁸. That last caveat matters for modern players: 1991 high gain and 2020s high gain are different animals, and the ShredMaster's distortion is best understood as a classic JCM-style voice rather than a modern metal saturation.

The pedal's most famous association is Jonny Greenwood. MusicRadar lists it "as used by Jonny Greenwood on Radiohead's Creep"⁶, and Guitar World notes the reissue "is perhaps most famous for Radiohead-style distortion," adding that putting a reverb pedal in front of it gets you into My Bloody Valentine territory⁹.

The controls: Gain, Contour and the rest

The ShredMaster carries five knobs: Gain, Bass, Contour, Treble and Volume⁴. The layout is shared with the Drivemaster Vintage Reissue, with one telling difference: the central knob is marked Contour instead of Middle¹.

The Contour knob is the pedal's signature control, and reviewers have mapped out its range in detail. Guitar.com's Richard Purvis found it "scooping it out as you turn it clockwise," with the sound "extra-clanky" all the way down and "almost Muff-like" all the way up¹. Marshall's own description, quoted by GuitarPlayer, says Contour "changes the character of the midrange while enhancing low and high frequencies"¹⁰. MusicRadar sums it up as a contour control in place of a mid: "you turn it up to scoop"⁶.

The Gain knob is more versatile than the pedal's name suggests. Purvis found that backing it off a few degrees from maximum gives a crunchy overdrive, and that at zero it "nearly qualifies as a tone-sweetening clean boost"¹. He also noted it cleans up well when you roll back the guitar's volume, writing that "it even passes the ancient blues players' sacred initiation test, cleaning up well with a twist of the pinkie on the guitar's volume control"¹.

History and versions: the 1991 original and the Bletchley reissue

The ShredMaster launched in 1991 as one of Marshall's second-generation pedals, alongside the DriveMaster¹¹¹. According to JHS Pedals' history of Marshall's effects, the DriveMaster was essentially the Guv'nor circuit with a better name and a cleaner look matching the Bluesbreaker and the Shred Master, and the Shred Master itself was originally called the Drive With No Name³. The original ShredMaster was discontinued in 1998 and replaced by the Jackhammer³.

For decades after that, Marshall declined to bring any of its vintage pedals back. MusicRadar had previously reported on "Marshall's refusal/unwillingness to reissue any of its Guv'nor, Shred Master, Drive Master and first Blues Breaker pedals"¹². That changed in 2023, when Marshall reissued the Guv'nor, Blues Breaker, Drivemaster and Shredmaster together as the Vintage Reissue series⁸.

The reissue is a deliberate reproduction. Marshall says "the ultimate care has been taken to ensure that this reissue accurately recreates that iconic Shredmaster sound," and the pedal is housed in an authentic mild steel chassis with the gold Shredmaster name, embossed Marshall logo and heavy-duty casing of the original². It is designed and hand-built at Marshall's Bletchley headquarters¹³⁶¹, which MusicRadar identifies as the company's UK Milton Keynes factory⁶. Guitar.com's review of the hardware found "the circuit board is a proper through-hole type," though the jack sockets are mounted in cheap-looking plastic casings¹.

ShredMaster versus DriveMaster

The two 1991 siblings are close cousins. In design terms the ShredMaster is "almost indistinguishable from the DriveMaster," with gold lettering instead of red and gray position markers on the knobs¹. The five knobs are the same set, except the central one is Contour on the ShredMaster and Middle on the DriveMaster¹.

The difference is gain character. The DriveMaster is a mid-gain overdrive, essentially a renamed Guv'nor circuit³, while the ShredMaster is the high-gain distortion based on the JCM900⁶¹⁴. Guitar.com's review of the pair found the ShredMaster "clearly the most angry" of the four Vintage Reissue pedals, and its sound at full gain "the most Marshall-like sound available from any of the four pedals in the range," though "we're talking fiery JCM, not creamy JTM"¹⁵.

What reviewers said

Guitar.com's Richard Purvis gave the ShredMaster reissue a rating of 8 and raised the question of whether it "might actually be the most versatile unit of the whole Vintage Reissue range," given its range from clean boost through crunchy overdrive to full distortion¹. He even found a use beyond rock: paired with the neck humbucker of a good semi-acoustic, "it'll even conjure up a bit of jazz boop"¹.

Premier Guitar's First Look at the reissue pedals covered the ShredMaster alongside its siblings, with Marshall positioning the original as its first-ever high-gain pedal¹⁵. Guitar World's coverage highlighted the Contour dial as the key to shaping the pedal's sound⁹.

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