Reading the diagrams
- Red arrows: Tone 1 (or 3). Blue arrows: Tone 2 (or 4). Purple and dark-blue arrows: the combined signal.
- WG wave generator (see pitch envelope), TVF time variant filter (TVF envelope), TVA time variant amplifier (TVA envelope). See also Tone structure.
Structure 1
No interaction: each Tone works independently. Structure 1 is the only one in which Tones 1 and 2 (or 3 and 4) don’t interact at all.
Structure 2
Mainly for doubling the filter slope. One filter cuts off at about −12 dB per octave; two in series reach −24 dB per octave.
Structure 3
Structure 2 plus the booster. Tone 1’s WG modulates Tone 2’s, and the booster clips the peaks, making techniques like PWM possible. See using the booster for PWM.
Structure 4
Like structure 3, but with Tone 1’s TVF moved after the booster, so both filters in series give the boosted signal a −24 dB per octave slope.
Structure 5
Structure 4 with a ring modulator in place of the booster, for unique, often bell-like sounds from simple or complex waveforms. See ring modulator.
Continue with Tone structures 6–10.
Tone-structure diagrams © 1998 Nathan Sheldon, based on the XP-80 Owner’s Manual. Credits & disclaimer.