Catalinbread Formula 51 Overdrive
All the way back in the 40's, Fender introduced the Champ amplifier, then known as the Champion 800. After a lengthy series of part swaps and circuit revisions, Fender arrived at the 5F1, otherwise known as the Tweed Champ, named so because of its unmistakable wrapping. It featured just one Volume knob (that went to 12!) delivering a myriad of tones from the humble circuit, from gently gritty cleans to honking, mid-heavy blown out distortion.
Unlike most amp-in-a-box devices, the Formula 51 features a preamp, a discrete power amp simulator and an output transformer to deliver the full touch-sensitive Tweed experience, with a grip of extremely interactive controls. The Sag control loads down the transformer to your taste, giving you some real-deal blown-out leads with the twist of a knob. The Tone control is straight out of the vintage amplifier playbook, incorporating the mid scoop control of the Framus Cobra amp.
This time-tested mod essentially turns the mid-leaning Tweed profile into the mid-scooped Blackface sound of later Champs. Run it at 18V for more headroom or stack it with other pedals to really dig into that transformer!
Sag, tone, volume, gain.