Benson Amps Benson Stonk Box

The Benson Stonk Box is a germanium fuzz pedal from Portland builder Benson Amps, launched in May 2023. Benson describes it as "our heavily modified version of a Tone Bender MK1 Fuzz (with Supa MK1 midrange tendencies)"¹², and it is the company's second thermally biased fuzz, following the Benson Germanium Fuzz².

What sets it apart from most vintage style fuzzes is Benson's Automatic Thermal Bias: a patented circuit that continuously monitors and warms the germanium transistors so the pedal sounds the same whether it is freezing or hot on stage². Guitar World's Jonathan Horsley described it at launch as a temperature-regulated take on early '60s fuzz circuits, priced at $279 / £289³⁴.

A Tone Bender MkI-style germanium fuzz

The Stonk Box builds on the Tone Bender MkI, one of the first British fuzz boxes available to the public, itself based on the Gibson-built Maestro Fuzz-tone. Delicious Audio's Paolo De Gregorio notes the Stonk Box is based on the Mk1 Tone Bender, "with its signature hairy, spitting, and aggressive sound that easily cuts through even the denser of mixes"². On the JHS Pedals channel, the pedal was presented as "a much more aggressive, velcro-y circuit. Think Tone Bender Mark One or Zonk Machine"⁵.

The original circuit is considered one of the hardest of the classic fuzzes to get right because of the difficulty in tuning germanium transistors; Benson claims its patented thermal bias technology solves that "easily and consistently"². Pedal of the Day framed the design goal as taking a classic 1960's fuzz and bringing its sound into the modern world without the flaws and inconsistencies of the original⁶.

The MkI lineage carries famous players. British Pedal Company notes the MkI was most famously used by Jeff Beck and Mick Ronson, defining tones on hit songs of the 1960s and 70s⁸, and stompboxes.co.uk's history records Ronson as a dedicated MkI user from his time with The Rats through his years with the Spiders From Mars, his main fuzz box for over a decade⁹. A modern recreation, the British Pedal Company Special Edition Master Built MKI Tone Bender, keeps that circuit available today.

The controls: Filter, Volume, Tone and Trim

The Stonk Box keeps the two controls of the original MkI, Filter and Volume, and adds Tone and Trim to expand the palette of sounds⁶. Benson's own descriptions of what each knob does, as published by Delicious Audio²:

There is also an internal trimmer, factory set. Turning it voids the warranty².

Automatic Thermal Bias and the warm-up LED

Germanium transistors drift with temperature, which is why vintage germanium fuzzes can sound different from one gig to the next. The Stonk Box's Automatic Thermal Bias circuit gently warms the 2N404 or 2N527 transistors to a preset operating point, so the sound stays consistent regardless of external temperature². Guitar World describes it as technology that continuously monitors and warms the germanium transistors to ensure consistent performance¹¹.

The pedal tells you where it is in the process with a two color LED²:

• Amber: the transistors are warming up, increasing their hFE (gain) and shifting the bias point.
• Green: the correct bias and hFE are set; the warmer is off.
• The LED toggles back and forth while the pedal is on, as the heater cycles.

Expect two to three minutes after plugging into power before the LED turns green and the pedal sounds correct³². The Stonk Box was the third Benson design to feature Automatic Thermal Bias, following the Germanium Fuzz and Germanium Boost launched in 2021³.

History: the MkI, the Zonk Machine and David Torn

The name comes from the circuit's family tree. On That Pedal Show, Chris Benson explained that "ston" is a reference to Zon, the Zonk Machine being one of the Mark One variations¹⁰, and the pedal comes stock with the thinned out bass sound of the first version of the Zonk Machine¹². The Zonk Machine has its own history: David Gilmour reportedly used one during the early years of Pink Floyd¹³.

The design also had a collaborator. Benson Amps' builder's notes say that when designing the Stonk, they reached out to David Torn to help¹². Torn is described as "a Mark One obsessive" who sent Benson "probably 10 different Mark One variants" to compare against during development¹⁰.

What reviewers said

Published reviewers have been positive. One review concluded that "it can surely handle your Keef riffs, but the range of this high-quality build goes well beyond that"⁷. On That Pedal Show, Dan said that if you want a fuzz without the usual fuzz problems, with control of the volume knob, and the perfect step between a great distortion and a great fuzz, buy it¹⁰.

On That Pedal Show, Dan summed up the pedal's appeal: "if you want a pedal that doesn't give you all the problems that a fuzz gives you in terms of falling out on the bottom end, with control of the volume knob, and the perfect step between a great distortion and a great fuzz, buy it"¹⁰. On JHS Pedals, the Stonk Box was presented as a new release in the Tone Bender MkI / Zonk Machine vein, "kind of more aggressive and gnarly sounding"⁵.

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