Benson Amps Stonk Box Fuzz adds thermal bias to Mk1 Tone Bender circuit

December 9, 2023 · 3 sources

Benson Amps has released the Stonk Box Fuzz, its second fuzz pedal and its second with automatic thermal bias, built on the Mk1 Tone Bender circuit¹². Guitar.com reported the launch on May 17, 2023, and put the price at $279.00². Delicious Audio published the builder's notes on December 9, 2023¹.

The pedal keeps the original circuit's Filter and Volume controls and adds Tone and Trim¹³. Benson describes Trim as a gain control ahead of the two amplifying germanium transistors, with the control turned all the way up matching the stock design¹. Filter adjusts gain and the bias point of the first gain stage, and Tone is a low pass filter at the end of the circuit that Benson says acts almost like a tilt EQ¹. The pedal is buffer and pedal order friendly, and Benson says it had to tweak the output circuit because there is no pickup simulation¹².

The bias circuit warms the germanium transistors, either 2N404 or 2N527, to a preset operating point using analog components¹²³. Benson says the pedal takes 2-3 minutes on average to sound correct after power-up, and that an amber LED means the transistors are warming while a green LED means the warmer is off¹. The pedal is designed to operate between freezing and 100F¹². It runs on a 9vdc center negative supply only, with no battery, and draws less than 100ma when the heater is engaged¹. The warranty is 2 years, excluding modification, trim pot manipulation, or damage¹.

Guitar.com reported that the Mk1 Tonebender dates from 1965 and was built by Gary Hurst². The Stonk Box follows Benson's Germanium Fuzz, a Fuzz Face variant¹².