Sola Sound Tone Bender MKI

The Sola Sound Tone Bender MKI is a three-transistor germanium fuzz box, first built in 1965, and one of the very first commercial effects pedals available in England¹². It was designed by Gary Hurst, a former Vox technician, as the British engineered answer to the American-made Gibson Maestro Fuzz-Tone, with the circuit modified to produce more sustain than its American counterpart³⁴. GuitarPlayer describes its character as "often choppy" with a high output, and Guitar World notes the MkI "sounds quite loud compared with the other Tone Benders"⁵³.

For a player today, the MKI matters as the starting point of the whole Tone Bender family: the fuzz that Paul McCartney used on the bass track of the Beatles' "Think for Yourself", that Mick Ronson carried from Hull into David Bowie's Spiders from Mars, and that Jimmy Page was photographed using during the Yardbirds years¹.

What the Tone Bender MKI does

The MKI takes a guitar signal and drives it into a clipped, sustaining fuzz voice built from three germanium transistors. Hurst's design was a modified version of Gibson's 1962 Maestro Fuzz-Tone circuit, changed to produce more sustain than the American pedal⁹. The result, in GuitarPlayer's words, is a fuzz with an "often choppy character and high output"⁵, and Guitar World's David Main and Rod Brakes found it "quite loud compared with the other Tone Benders, which is surprising considering it's the first in the line"³.

The pedal runs on nine volts, where the Maestro FZ-1 it descended from ran on three³. Stompboxes.co.uk notes the MKI "bares some tonal traits of its origins, the Maestro FZ-1"¹⁰.

Three germanium transistors in wood, steel and cast aluminum

The MKI's circuit is a simple three-transistor germanium design. Guitar World's history describes it as using "normally two Mullard OC75s and one Texas Instruments TI2G381"³, while stompboxes.co.uk describes the MKI circuit as loaded with "a single Mullard OC75 and two Texas Instruments 2G381 devices"⁸. One documented early unit, the Bill Puplett example, is notable for a very unusual 4μF input capacitor and an Impex S3-1T transistor in the second position⁹.

The earliest examples were built into wooden enclosures, with the electronics assembled on stripboard, also known as Vero board, and three black glass Mullard germanium transistors⁹. Guitar World describes these first units as having "the classic cheese-wedge kind of shape, but are made of wood and were pretty fragile"³. Hurst soon moved to folded steel enclosures, and later examples appear in cast aluminum, with the parts assembled on perforated circuit board rather than stripboard, and still later units built point-to-point on a dedicated board⁹.

The first few Tone Benders were sold as Gary Hurst designed units, with hand-applied dry letter transfers, and were not sold as Sola Sound pedals; the final version of the MKI carried the silk screening of "Sola Sounds Ltd" and was sold as a Sola Sound product⁸.

History: Gary Hurst's answer to the Maestro Fuzz-Tone

Gary Hurst, a former Vox technician, began experimenting with fuzz circuits in 1964, and Tom Jennings of Vox was not interested, so Hurst teamed with the Macari brothers⁷. The first Tone Bender, later christened the MKI, was based on Hurst's modified Maestro fuzz¹¹, essentially a modified Maestro FZ-1 designed in 1965³. JHS Pedals describes the arrival plainly:

The MKI was one of the very first commercial effects pedals available in England¹, and by 1969 several versions and variations existed, with copies produced by Vox, Jennings, Coloursound and JMI².

Later versions, from the MK1.5 to the Mk. IV

The Tone Bender line evolved quickly after the MKI, with circuit alterations continuing into the so-called MkVI versions of the 1970s¹².

• MK1.5: A two-transistor transitional model between the MKI and the Professional MKII, built by Sola Sound in the mid-1960s and typically fitted with two Mullard OC75 germanium transistors, though some early examples carried Impex S3-1T transistors. It was sold at a variety of shops across the UK, including by Jennings in Dartford, and was discontinued by Sola Sound later in 1966. The "MK1.5" name was applied by collectors in modern times, not by Sola Sound. Over 40 original pedals are known to have survived¹³.
• Professional MKII: Introduced around 1966, a three-transistor circuit (OC75) based on the MK1.5 version with an additional amplifier gain stage¹⁴¹⁵. The Vox Tone Bender Professional MKII was supplied by Sola Sound via Macari's Musical Exchange and became one of the best-known versions¹⁶. The MKII circuit was discontinued in 1968¹⁴.
• MKIII: The demise of the MKII resulted in Sola Sound's invention of the Vox Tone Bender MKIII¹⁶, and Sola Sound continued to supply Vox with the MKIII until well into the 1970s¹⁷.
• MKIV: The same circuit as the MKIII in a smaller enclosure, differing only in enclosure and graphics at launch¹⁸. From approximately 1971 the model designation was removed and the pedal was known simply as the Sola Sound Tone Bender; it was discontinued in the late 1970s¹⁸.

Later Tone Benders such as the Supa Tone Bender from 1973 and the Jumbo Tone Bender from 1976 were silicon Big Muff clones unrelated to the earlier Tone Benders¹⁹.

Who used the Tone Bender MKI

The MKI's user list is remarkable given how few pedals survive. Fuzzboxes.org calls it "the only vintage effects pedal (of any sort) where there are actually more confirmed examples of notable artists using it than surviving examples of the pedal"¹.

• Paul McCartney used the MKI on the bass track of the Beatles recording "Think for Yourself"⁸, a use Aclam Guitars also documents²⁰.
• Mick Ronson first acquired the model during the 1960s while a member of the Rats in Hull, and continued using the MKI on stage with David Bowie's Spiders from Mars in the early 1970s¹. Guitar World notes he used a MkI Tone Bender throughout his years with Bowie⁷.
• Jimmy Page was photographed on several occasions during the Yardbirds years using a Tone Bender in a very early cast aluminum enclosure¹. His later Led Zeppelin fuzz work is associated with the MkII, which GuitarPlayer says he used on his early recordings with the band¹².
• Barry Stedman acquired a gold Tone Bender MKI after hearing Jeff Beck using one on "Heart Full of Soul"¹.
• Hume Paton was photographed using a Tone Bender MKI during a performance with the Poets, from Glasgow¹.

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