The Effectrode Blackbird Vacuum Tube Preamp, occasionally called the Blackbird SR-71, is an all-tube preamp housed in a compact pedal. It features two completely independent channels - the clean channel, a replica of the classic "Blackface" circuit designed by Leo Fender, and the overdrive channel, a variation on a hot-rodded 4-stage Dumble/Soldano circuit. Each channel has its own EQ controls based on the tonestacks of "Blackface" amps, and the pedal has tube buffered output and a transformer balanced out for recording.