We sliced a few samples from a vocalist friend and launch it live to make the melody.
Several scenes in the Octatrack are used to control delays tempo, filters, and slices selection with the fader. Also the drummer is hearing the metronome in its headphones to keep the band in sync.
The Analog Keys also plays another melodies, and it is recorded in the samples the Octatrack is playing.
Just ask me if you have any answers.