 Each top-octave note is fed to a simple digital counter IC, which divides by 2, 4, 8, 16, and so on, generating all the lower octaves of that note.So the Freeman has three complete sets of tones that can be mixed to create more or fewer overtones in the sound, as one rank is tuned an octave below the other from the beginning.The 'High' and 'Low' buttons on the front panel select which group is selected, or both can be mixed for a thicker octave overtone on each note.