The TB-1 is an all tube upper octave generator similar in concept to the Octavia. Controls are as follows: gain and volume. At low gain settings it has a clean ring modulator-like tone and as you raise the gain more harmonics are added to the octave giving you a Purple Haze like tone. There are 2 footswitches. One bypasses the entire effect. While the other bypass the octave effect leaving an all tube overdrive with tone ranging from clean to a nice crunchy overdrive.