Hornby Skewes Zonk Machine I

The Hornby Skewes Zonk Machine I is a germanium fuzz pedal made in Leeds, England, between 1965 and 1966¹. John Hornby Skewes, a Leeds firm, developed it to meet the demand created by the mid-1960s fuzz boom², and the pedal was built by Charlie Ramskirr of Wilsic Electronics². Its circuit is almost identical to the Tone Bender MKI³⁴⁵, and it is remembered for a famously bright, searing fuzz⁴. Very few were made, and originals are highly sought-after by collectors and fuzz enthusiasts².

A bright, early British fuzz

The Zonk Machine arrived at the end of 1965, when British makers were racing to build fuzz boxes after the Maestro FZ-1 inspired the Great British fuzz pedal boom²⁸⁹. John Hornby Skewes of Leeds wanted in on this growing market and decided to develop his own fuzz box to meet demand². The result was housed in a simple steel box with two controls², and Zonk Machines were housed in enclosures made of folded aluminum, painted a teal hammered finish⁷.

The pedal's place in the fuzz family tree is clear from several angles:

• The British Pedal Company's history calls the circuit similar to the MKI Tone Bender², and stompboxes.co.uk describes it as almost identical in its circuitry⁴
• Fuzzboxes.org found the circuit resembled Gibson's Maestro Fuzz-Tone but was much more similar to the Tone Bender MKI, likely its true inspiration⁷
• Guitar FX Layouts describes it as topographically identical to the MKI apart from a 33K resistor³
• stompboxes.co.uk calls it "the freakier, weirder looking cousin to the Tone Bender MKI"⁵

The sound is where the Zonk Machine I earned its reputation. MusicRadar notes the original became something of a legend in the world of fuzzboxes, with a famously bright fuzz¹⁰. Builders agree: Guitar FX Layouts calls the Zonk very bright, and suggests input cap values between .001uF and .01uF to tame it³. One verified PNP build found a 1nf cap on the input to ground removed sizzling bacon noise artifacts without killing the highs, while the original 1nf input cap sounded tinny and a 10nf cap gave a beefier sound with stronger midrange³.

The brightness can also be unpredictable. Comparing Zonk fuzz controls with another vintage unit, David Main noted on Guitar FX Layouts that "Zonk's can be either all on nothing at times in this regard"¹¹.

The fuzz control

The Zonk Machine I has two controls, and their names are misleading to a modern player. The Fuzz control controls the volume, while the switched Swell control controls the amount of fuzz².

Under the hood, the Fuzz pot essentially adjusts the bias of Q2, the second transistor³. Guitar FX Layouts recommends a log/audio taper pot, and notes some units came with a 25k Log Fuzz pot and a 220k resistor instead of 470k³. For builders chasing the pedal's wilder side, the site suggests an SPST switch to bypass the 2.2M resistor for what it calls "nasty, all-out craziness"³.

Transistors and versions

The Zonk Machine I uses three germanium transistors¹², though the maker advertised it as featuring a highly developed circuit using expensive American transistors². Fuzzboxes.org documents the production changes across the pedal's short life⁷:

Guitar FX Layouts measured an original unit with Q1 as a TI AO2 at 180 hfe, Q2 as a Mullard OC75 at 78 hfe and Q3 as an OC44 at 58 hfe³. A verified PNP build by commenter OcularDawn used Q1 OC75, Q2 NKT275 reissue and Q3 OC75³.

Originals came in both PNP and NPN ground schemes, and the PNP version is positive ground, which matters to anyone powering a reissue or clone on a modern pedalboard: a positive ground unit cannot be daisy chained with negative ground devices¹³.

The Zonk Machine I and II

In 1967 Hornby Skewes replaced the original with the Zonk Machine II, a re-engineered Zonk Machine I¹³. The II used two PNP silicon transistors instead of the earlier three germaniums¹³, and builders describe it as more stable, smoother and less dark sounding than the I¹³. Like the MKI, the Zonk Machine I was only made in small numbers before being updated with a more modern, easier to produce unit¹.

Where it went

The Zonk Machine was discontinued in 1968⁷. The British Pedal Company's history attributes the end of the product to the death of designer Charlie Ramskirr in 1968², while Fuzzboxes.org reports the same account from Skewes in 2015 but calls it unreliable⁷. Either way, very few original units were produced between 1965 and 1968², and originals now overwhelmingly resurface in Canada, where the company was exporting fuzz boxes as early as 1966⁷.

The pedal's later life has been busy. The British Pedal Company released a reissue made in England in 2013¹, and MusicRadar reported in 2024 that JHS has two of its own versions out, a Vintage Series with the larger wedge-style enclosure and one in its Compact Series¹⁰.

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