All the way back in the ‘40s, 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 knob—volume—that went to 12 (in your face, Nigel), and if you’ve ever played one, that’s about all it needs. Just that one knob can coax 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!

CONTROLS

SAG: START WITH THIS CONTROL AT ZERO. Each setup is different and will react differently with this knob. This control essentially loads down the power amp and transformer section, giving you a spongier attack and a more blown-out quality to the overall tone. This control is highly interactive with **Gain**, Tone, the pedals run in front and even the input voltage, and as such it is designed to give you the widest range of tones no matter what you’re working with. When set all the way down, the power amp and transformer are running at full tilt, and the section begins to load down as you inch up the dial. The stronger the signal fed into the power amp and output transformer, the higher you can turn up the Sag. More on that later.

Tone: Some time ago, back when amp geeks had just started to trade information over the Internet, a “mids” control mod began popping up that was pulled from an amp called the Framus Cobra. This control, wired in reverse, essentially scooped out the mids and turned a burly, mids-focused Tweed amp into a more scooped “blackface” model. And so, we have given you this control as a Tone knob. When it’s all the way down, you’re in Tweed town. When it’s maxed, you’ve got a “blackface,” Jack.

Volume: The Formula 51 sounds great when this knob is set at any position other than zero. Try it!

**Gain**: This knob functions as the “volume” control on the original Tweed Champ; it controls the preamp gain, or how much juice hits the power amp and transformer. When it’s all the way down, you’re treated to the slightly gritty cleans of the original, as you roll it up you get a cranked Tweed and finally some heavy distortion all the way at the end.