Formula No. 55 guitar overdrive pedal efect 55 with an incredible range. Big and powerful, yet refined, the Formula No. 55 provides the preamp section of the classic Tweed 5E3 Deluxe using an all-discrete JFET-based signal path. The advantage is a really authentic tweed amp response. Formula No. 55 has the switch to control HI / LO modes and the potentiometers for Tone, Presence, Volume and Master functions.