Formula 51 (Foundation)

The Catalinbread Formula 51 recreates the Fender 5F1 Tweed Champ, the five-watt single-ended amp that Duane Allman and Eric Clapton used to cut the Layla sessions. A single 6V6 power tube running at its absolute limit gave those recordings a compressed, harmonically saturated character that no larger amp could replicate.

Unique among the Formula series, the Formula 51 includes a Sag control that simulates the power section compression of a Champ pushed past its limits. The circuit models both the preamp and the output transformer as discrete stages, capturing how the tiny amp's entire signal path contributes to the tone. Gain sets the preamp drive, Tone borrows its mid-scoop voicing from the Framus Cobra circuit, and Volume controls output.

The Champ's appeal was always about what happened when you turned a small amp all the way up. The Formula 51 puts that exact moment in a pedal. Runs on 9-18V DC for variable headroom.