The OCT-1 is an all analog upper and lower octave generator. The lower octave gives a clean synth like tone. The upper octave circuit uses 3 NOS germanium transistors to give a ring modulator like tone (there is an internal trimpot to add additional harmonics/fuzz to the upper octave). The dry channel also uses germanium transistors (2). All 3 channels have their own volume controls. There are 11 knobs: Trigger, Gain, Master Volume, LO-OCT-VOL, DRY-VOL, HI-OCT-VOL and a 5 band equalizer. These circuits are then mixed together into a 2 stage tube section. The tube section is capable of clean to heavily distorted tones. The Octavator is compatible with several tube types such as: 6SL7, 6SN7- These 2 are the older large style octal preamp tubes. I designed an adapter so that a 12AX7, 12AT7, 12AU7, 12AY7, 5751, and a GCG7/6FQ7 tube can be used. No other effects pedal offers this many tube choices. The OCT-1 is for single note leads only. However if you turn down the lower octave, you can play chords.