AULOS is a polyphonic physical-model wind instrument synthesizer. The bore is modeled with two coupled waveguides — a primary resonator at the full pipe length and a secondary resonator at a harmonically scaled sub-length — sharing a single excitation source that morphs continuously from flute (jet delay function) to reed (loop saturator). Both modes are always present in the mix; EDGE sets the morph position. The stereo R voice is a complete second instrument sharing all tone controls.
Register is determined by the ratio of the FINGER pitch to the PIPE fundamental. When the finger frequency is near twice the pipe frequency the bore shifts to the overblown octave; near four times, it shifts up a further octave. The transition smooths over roughly 200ms so the timbre morphs rather than snapping. Energy-overblow is a separate mechanism — very loud playing can momentarily push the mode upward independent of the finger position.
The graphical display shows two tube cross-sections, L on top and R below. Each tube depicts bore length, breath fill level, a standing-wave indicator, register, overblow outline, air lines streaming from the bell exit, and chiff line bursts on note attack. The R tube dims to show the drone level reduction in drone mode.
Key controls:
- PIPE V/OCT input + PIPE TUNE knob (-1 to +4 oct): sets the resonant fundamental of the bore — the pitch the resonator naturally wants to sustain. Only this determines the resonant pitch; it does not have to track the played note.
- FINGER V/OCT input + FINGER TUNE knob (±1 oct): sets the fingering pitch, which determines bore length and register. In a standard melodic patch this tracks the played note. The ratio of FINGER to PIPE governs which register the bore locks to.
- GATE input: polyphonic up to 16 voices. Voice count follows the highest channel count across GATE, FINGER V/OCT, and PIPE V/OCT.
- BREATH knob + trim + CV: breath pressure. Sets the ASR envelope height and excitation amplitude. Non-linearly scaled so low values are gentle; higher values push the instrument louder and harder.
- EDGE slider + ATT + CV: excitation morph. Near zero: flute jet behavior — breathy, hollow, mode-dependent. Near maximum: reed saturator — buzzier, harmonically denser, more stable across registers. Both modes are always present.
- JET slider + ATT + CV: bore shape parameter. Affects jet bias, secondary waveguide coupling level, and bore damping character. Experiment to find the core tone quality.
- DRIVE slider + ATT + CV: loop saturator gain. Increases harmonic richness and drives the bore toward stronger self-sustain.
- RES slider + ATT + CV (labeled Lip / Holes on panel): loop feedback gain. Higher values give a more resonant, sustaining tone. If the instrument goes unstable or squeals, reduce this.
- AIR slider + ATT + CV: breath noise amplitude. Injects noise into the excitation continuously. Displayed as the streaming air lines at the bell exit.
- CHIFF slider + ATT + CV: chiff transient duration and amplitude on each gate rise. At zero there is no attack burst; at maximum the chiff is long and loud. Displayed as the outer line bursts at the bell exit on each new note.
- AULOS slider + ATT + CV (±1 oct): R voice pipe pitch offset. Zero is unison. Positive raises the R pipe; negative lowers it.
- WARMTH slider + ATT + CV: bore damping. Sweeps a low-pass filter inside the loop from fully open (bright) to deep cut (warm, dark).
- VIBRATO input + ATT knob: when unpatched, the internal LFO drives pitch FM and breath wobble simultaneously. When patched, the external CV takes over pitch FM only; depth is set by the ATT knob in both cases.
- Manual Gate button: holds the gate high for all voices without a cable.
- Drone button + LED: toggles drone mode for the R voice. In drone mode the R voice gate is locked permanently on and plays at a slightly lower level than the envelope-gated L voice. DRONE CV is a gate-triggered toggle.
- AUDIO IN input + AUDIO IN GAIN knob + trim + CV: injects external audio directly into the bore loop before the waveguide, exciting the resonance from outside.
- VOLUME knob + trim + CV: output gain, 0 to 3x.
- ENV output: polyphonic breath envelope.
- RMS output: polyphonic excitation dynamics follower.
- AUDIO L / AUDIO R: stereo outputs. The R voice only processes when AUDIO R is patched and is cleared on reconnect to avoid stale buffer playback.
- Blue VU (left cluster): breath envelope level per voice.
- Yellow VU (right cluster): excitation dynamics level per voice.
Context menu:
- Aulos R Voice Mode: Tracking (interval preserved) — the R finger shifts with the AULOS offset so both voices play the same interval in every register. Two Pipes (fixed registers) — R finger is independent and each pipe finds its own register from its own pipe frequency.
- Resonator: Waveguide Gain (raw loop input scaling for overall level balance), Decay (ring-off time after the gate falls).
- Envelope: Attack and Release (0..1 exponential time mappings), Attack Curve and Release Curve (negative = logarithmic, positive = exponential).
- Vibrato: Rate in Hz (3..12), Breath Coupling (how much the LFO modulates breath alongside pitch).
- Articulation: Legato toggle. When enabled, held-gate pitch changes glide rather than retriggering; the waveguide briefly dips feedback at each slur transition for the audible give between notes. Legato Glide Time sets the portamento duration in ms.
- Dynamics Envelope: Follow Time (integration time of the RMS follower driving the ENV and RMS outputs).
- Panic: immediately clears all waveguide and resonator energy.