Marshall Supa Fuzz

The Marshall Supa Fuzz is a germanium fuzz pedal created in 1966 by Gary Hurst for Marshall, Jim Marshall's amplifier company, and built for guitar and bass¹. Under the Marshall name sits a circuit that will be familiar to anyone who knows British fuzz of the 1960s: Sola Sound's Tone Bender. Most Supa Fuzzes carry a three-transistor Tone Bender MKII topology, packed into a distinctive sand-cast metal housing²³.

The pedal was made in England by Sola Sound from the mid 1960s to the early 1970s, with Marshall taking over the manufacturing itself in 1968²⁴. It ran for over a decade, which stompboxes.co.uk's history calls the longest living MKII variant⁵.

A Tone Bender circuit in a Marshall box

The Supa Fuzz is based on Sola Sound's Tone Bender circuits¹. Sola Sound, the London firm behind the Tone Bender line, was one of a handful of companies with agreements to build fuzz boxes for other makers, and Marshall was among them; Sola Sound began mass-producing Tone Benders in 1966, the same year the Supa Fuzz appeared². The same MKII circuit was produced under several names: VOX, Marshall (Supa Fuzz) and Rotosound (Fuzz Box) all sold versions of it⁶.

GuitarPlayer's Dave Hunter describes the arrangement plainly:

Premier Guitar's Tone Bender history adds that with minor alterations, the MKII was also sold as the Marshall Supa Fuzz, Park Fuzz Sound, and Rotosound Fuzz Box⁷. So the Supa Fuzz is best understood as the Marshall-branded member of a family of Tone Bender MKII pedals that all came out of Sola Sound with small component differences.

The Filter control and the earliest tone filter

The production Supa Fuzz carries two controls: Level and Filter. On the main MKII-circuit run, that Filter control is not a tone control at all. Fuzzboxes.org's history explains that the "filter" control on those SupaFuzzes was the same as the "attack" control on a Tone Bender MKII, rather than a tone filter².

The label is a leftover from the pedal's beginnings. The very first examples of the Supa Fuzz actually featured a MKI circuit variation with a crude tone filter and pre-set gain levels, with the control labeled "Filter"⁵. Delicious Audio's Gearphoria feature describes those earliest Supa Fuzzes as using a version of the MkI circuit, boasting a tone filter and pre-set gain levels⁸. When the MKII circuit replaced it, the knob became a bias control but the name stayed on the panel.

Skreddy Pedals' Marc, whose own fuzz designs trace this lineage, describes what that control actually does⁹:

In practice, turning it down low pulls the transistors out of their sweet spot and cuts the signal, while turning it up brings the fuzz to full saturation. Some main-production units from 1966 through 1967/68 had a limiting resistor on the Filter control so the amount of fuzz could only ever reach 90% saturation⁵.

Versions through the production run

The Supa Fuzz bounced through several iterations during its run⁸. The line of versions, as the histories describe it:

The enclosure itself changed too. Early Sola Sound-built units came with gold-topped control knobs as used on Marshall amplifiers, followed by taller silver-topped knobs by 1967, and Marshall re-fitted gold-topped knobs on its own version². Later Marshall-era variants moved from screen-printed to embossed enclosures, and potentiometer date codes show the embossed-lettering SupaFuzz was still being built by 1973². Marshall continued producing a slightly different looking version until 1972 or longer⁶.

The Marshall-branded version, sometimes identified by the internal code 1975, differs from the Tone Bender MKII in a few component values: the input capacitor is 10µF instead of 5µF, the bypass capacitor on the "filter" pot is 10µF instead of 5µF at the "attack" pot, and the transistors are OC75 instead of OC81D¹¹. TONEHOME describes the result as nearly the same sound as the Tone Bender MKII, a bit more on the bassier side due to the larger input capacitor¹¹. A 0.01µF capacitor from input to ground on the Model 1975 cuts even more treble¹¹.

Clones and collector prices

Original Supa Fuzzes are collector items now. Delicious Audio's Gearphoria feature, republished in 2016, put it directly⁸:

There are a few builders that make clones of the pedal⁸. Delicious Audio names Pigdog, Castledine, DenTone, CBC Pedals and Farmland as clone makers⁸. Toetags Electronics announced a Supa Fuzz in May 2016, based on the classic and rare Marshall Supa Fuzz, at $225 MSRP¹². Tru-Fi builds a hand-made recreation with Level and Attack controls just like the original, using 3 vintage Mullard OC75 transistors¹³. R2R Electric offers the Supa MKII Fuzz, its own take on both the Sola Sound Tone Bender MKII and the Marshall Supa Fuzz, built with 3x Black Glass or TO-1 vintage and NOS germanium transistors and Daka-Ware control knobs¹⁴¹⁵.

For players who want the circuit without the collector price, the fuzz pedals family page covers the wider Tone Bender lineage, including the Sola Sound Tone Bender MKI that gave the earliest Supa Fuzzes their circuit.

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