Ambi Effect Partial Trace

s3g Ambi Effect Partial Trace 64 listens to a complete 1OA through 7OA ACN/SN3D field, follows its strongest stable sinusoidal components, and returns a continuously resynthesized ambisonic trace. It treats the field as one scene: adjacent Listener pickups help locate a partial instead of creating separate copies of it.

Workflow

1. Place Partial Trace after an ambisonic encoder or encoded recording and select the input order.
2. Follow it with an ambisonic decoder. Additional Ambisonic effects may be placed before the decoder when their supported order and channel count match the field.
3. Leave Body at AUTO and Topology at LOCAL.
4. Begin with Mix near 40%, Trace gain below 0 dB, and approximately eight to ten partials.
5. Raise Sensitivity until the field display follows the desired tonal material without continuously filling with noise.
6. Raise Smear to let released and moving partials overlap as a spectral trail. Press Freeze to hold the currently sounding trace, then Unfreeze to resume live tracking.
7. Use Apply / Bypass Trace for comparison, then explore Transpose, Cross, Diffuse, or Roaming topology.

Signal Flow

1. Decode the active HOA order onto the order-adaptive Listener body.
2. Analyze the omnidirectional component in overlapping 2048-sample windows and select spectral peaks inside the Low and High limits.
3. Match new peaks to existing tracks by frequency so partial identity can persist between analysis frames. Smear narrows that match and lengthens decay, allowing motion to leave overlapping trace voices.
4. Measure each accepted frequency across the Listener pickups. The strongest region owns the partial while nearby evidence refines its spatial footprint.
5. Resynthesize the tracks as smoothly moving sinusoids, apply topology and the directional mask, and re-encode the correction into HOA.

Tracking is global rather than channel-by-channel. Ambisonic channels are spatial basis components, not independent stems; analyzing every component as a separate sound would multiply detections and damage the scene. Partial Trace instead uses the complete encoded field to produce one reconciled track bank.

Freeze takes an audible snapshot of the active frequencies, amplitudes, and Listener ownership. Analysis input continues to fill in the background, but it cannot replace or release the held tracks until Unfreeze. Transpose, topology, mask, Mix, and gain remain active while frozen. If the Listener body changes during Freeze, ownership is reassigned by nearest direction so the held field is not discarded.

Listener Body and Topology

AUTO uses Icosa12 for 1OA and 2OA, Dodeca20 for 3OA, and Sphere24 for 4OA through 7OA. The editor shows input activity, resynthesized trace activity, and mask attenuation at those virtual pickups. Use the Side, Top, and 3/4 cameras or drag the field to inspect it.

• LOCAL returns each partial to the region where it was heard.
• CROSS exchanges the trace with the opposing Listener region.
• DIFFUSE shares it through neighboring regions.
• ROAMING moves the trace around the Listener body at Roam Rate.

Controls

Level, Tracking, and Safety

New tracks use smoothed amplitude, frequency, and spatial ownership. Missing tracks fade according to Release instead of stopping abruptly. Smear progressively extends that decay—up to approximately 30 s at extreme Release settings—and increases temporal overlap, while the sixteen-partial ceiling keeps the voice count bounded. Apply / Bypass, Mask Dry, the wet mask, Mix, Trace, Transpose, and Output move continuously. An Order or Listener Body change briefly fades the wet field to silence, changes geometry, and fades it back in; HOA channels entering or leaving the selected order are also gain-ramped.

A linked trace governor reduces the complete Listener resynthesis before its soft bound when overlapping partials would exceed a 0.5 peak. Every pickup receives the same gain, preserving the directional pattern; GOV appears in the title status only while reduction is active. The complete HOA output then uses the same linked -1 dBFS guard as Resonance Print, after the smoothed Output stage. The guard also uses one gain for every channel so it does not rotate or deform the field.

A dense or noisy input can create a restless trace even at a modest level. Persistent GOV or SAFE activity means the effect is operating as a dynamics stage; narrow the Low / High range, reduce Partials or Sensitivity, or lower Trace, Mix, or Output for a more transparent result. When two sources sustain the same frequency at once, their spatial evidence may combine; increasing Track time and reducing the track count usually makes that ambiguity less conspicuous.

REAPER Routing

Set the track and plugin pins to the complete channel count for the selected order—4, 9, 16, 25, 36, 49, or 64—with one-to-one channel mapping. Partial Trace adds no declared host latency. Save and load through the host normally, or use the title-band LOAD and SAVE actions for complete plugin presets; selecting INIT restores the parameter defaults. The complete control state and camera view are stored in the project. When Freeze is active, the held sinusoidal bank—frequency, phase, amplitude, and directional ownership—is stored too, so the frozen sound returns without embedding source audio.