Ambi Encoder Modal

Ambi Encoder Modal is a spatial instrument built from four to eight independent resonant bodies. MIDI, a mono actuator input, and an internal Listener / Actuator can excite the bodies, which are then placed in an editable field and encoded directly as first-, second-, or third-order ACN/SN3D.

The body names describe musical starting points rather than replicas of specific instruments. A shared 96-mode pool keeps processing predictable: fewer bodies sound more detailed, while more bodies create a denser ensemble.

Ambi Encoder Modal GUI showing modal bodies, Listener and Actuator controls, projection, body AED, signal path, and camera controls — Ambi Encoder Modal with modal-body, Listener / Actuator, projection, body AED, signal-path, and camera controls.

Workflow

Choose 1OA, 2OA, 3OA, or 8 BODY STEMS, set the track to the corresponding 4, 9, 16, or 8 channels, and insert Ambi Encoder Modal.
With ACN/SN3D selected, follow it with an ambisonic decoder. With 8 BODY STEMS, route the eight ordinary lanes to the intended main speaker outputs, a downstream direct panner, or Output Autogain Stereo/Quad for fold-down monitoring.
Choose a Body and begin with four Bodies. Increase the count when a broader ensemble matters more than detail within each resonator.
Play MIDI notes or send a mono signal to Modal Actuator In. The input excites the resonators but is not mixed dry into the output.
Use Listener / Actuator Routing and Behavior to move sustained energy through the ensemble. DIFFUSE with DRONE is a useful starting point for continuous fields.
Set Azimuth, Elevation, and Body Spread, then drag individual bodies in the field when the generated constellation needs adjustment.

Signal Flow

MIDI, Modal Actuator In, and the Listener / Actuator energize the resonant bodies. No separate click, noise burst, or dry input is added.
The shared mode pool is divided among the active bodies. Body choice and character controls determine their pitch regions, decay, beating, and variation.
The Listener hears the internal field and directs continuous drive according to the selected Routing and Behavior.
Each body combines contact and radiated tone, then receives its generated or manually edited spatial position.
The normal output is HOA. 8 BODY STEMS instead provides one post-body signal per lane.
LIFT supports quiet sustained material, OUT sets the final level, and a linked guard protects all output channels together.

Choosing a Body

Group	Choices	General character
Bronze	Deep, Tiered, Broad, Bright	Long ringing fields ranging from low and weighty to bright and agile.
Plates	Carbon Laminate, Glass, Aluminum, Spruce	Clearer separated partials, directional variation, and a wide range of decay colors.
Shells and ceramics	Steel, Porcelain, Porous Earthenware	Dense or clustered resonance, from persistent metallic sustain to softer damped color.
Membranes	Tensioned Skin, Loaded, Coupled, Cavity, Loose	More pitch-centered bodies with beating, weight shifts, air interaction, or unstable tension.

Body choice sets the starting character. Size, Damp, Irregularity, Coupling, and the per-body variation controls can move any choice well beyond that starting point. Bodies in one ensemble are related but not identical.

MIDI and Actuator Input

The plugin exposes one note input named Modal Actuator MIDI In. Note pitch offsets a body around C4, and velocity sets its excitation. New notes prefer idle bodies; dense retriggers are gently limited so they do not overload one resonator. Note-off does not cut off an existing modal tail.

MIDI and Modal Actuator In are additive. The mono input can carry envelopes, contact sounds, or audio, but it only excites the resonators and is never heard as a dry signal. The Listener / Actuator can sustain and redistribute that energy after the initial excitation.

Spatial Body Editor

TOP and SIDE are editing views; 3/4 provides an overview. Drag bodies in Top or Side, click to select them in 3/4, and drag empty space to orbit the camera. The minus and plus buttons change scale. RESET removes manual offsets and returns body distances to 1.0.

The selected body also has automatable AZ OFFSET, EL OFFSET, and DISTANCE controls. These are added to the global Azimuth, Elevation, and Body Spread settings. Body color remains a position cue, while the surrounding halo shows live energy.

The neutral E1–E4 or E1–E8 diamonds are Listener pickups. Their halos show what the Listener hears, and moving route markers show where actuator force is going. They are control displays, not extra audio outputs.

Primary Controls

Panel	Controls	Role
Output	Lift / Out / Order / Format	Supports quiet sustained fields, sets output level, and selects HOA or eight body stems.
Modal Body	Body / Bodies / Size / Damp / Irregularity / Coupling / Drive Position	Chooses and shapes four to eight resonators within the shared mode pool.
Listener / Actuator	Ears / Routing / Drive / Behavior / Input	Chooses the Listener, directs continuous excitation, and sets the mono actuator contribution.
Projection	Azimuth / Elevation / Body Spread	Places and distributes the body centers in the ambisonic field.
Body Character	Tone Center / Variation / Mode Angle / Contact–Radiation / Air Level	Changes spectral color and the balance between contact and radiated sound.
Body AED	Az Offset / El Offset / Distance	Edits the selected body relative to the generated constellation.
Field View	Top / Side / 3/4 / − / + / Reset	Controls the camera, direct body editing, and layout reset.

How It Behaves

Each body is a bank of resonances with its own tuning, decay, excitation, and radiation balance. Close resonances create beating, while Irregularity and Coupling keep an ensemble from behaving like several identical copies.

The shared 96-mode pool is divided among the active bodies. Four bodies receive the most internal detail; adding bodies creates a busier spatial texture with fewer resonances per body.

Sound and position remain separate. Body Spread and the AED editor move a body without changing its tuning. Likewise, changing a body family or Size does not move it in the field.

Lift and the final linked guard manage level after the resonators. They preserve the balance between ambisonic channels, so protection does not pull the field toward a different direction.

See Modal Synthesis and Physical Modeling for the research background.

Presets

The 25 sustained presets cover low bronze fields, bright and muted plates, moving constellations, and the five membrane types. DEEP FIELD is the default. Presets describe continuous playing conditions, not sampled instruments or libraries of attacks.

Host and Interface

The bundle is s3g_ambi_encoder_modal.clap and appears as s3g Ambi Encoder Modal 16. Its native 1160 × 760 interface includes Preset, Load, Save, guarded Random, the main synthesis and spatial panels, and the editable field view.

Limits

The body families are compact musical profiles, not calibrated physical replicas. The shared mode pool also means that eight-body settings deliberately contain less detail per body than four-body settings.