Treatment

Opinion

Treatment is at its best as the thing you put on a bus that sounds like it is in the wrong room. Reach for it on a bass-heavy mix that has lost its foundation, or on a drum bus that is boomy but not really. It is a panel, not a tame, so it works hardest in the low mid and leaves the top alone.

Start at the defaults and listen to what the readouts say: a 100 mm cavity with a 50 mm gap puts the resonance around 173 Hz, which is where most unwanted energy actually is. Then move Flow Resist and listen for the sweet spot. Both too open and too dense absorb much less, and finding that by ear is the thing worth doing once.

Randomise is for finding panels quickly while writing, not for playing. Save the one you like.

Functionality

A facing sheet of surface mass in front of a porous fill, with an air gap to the wall. That is a mass-air-mass resonator, and Treatment computes it from the physics rather than from a tone control: resonance follows w0 = c·sqrt(rho0 / (m·D)), and absorption peaks where the fill’s flow resistance matches the characteristic impedance of air, which means the panel gets worse if you push the fill too far in either direction. Cavity and Air Gap are in millimetres, Facing Mass in kg/m² and Flow Resist in Rayl/m, because that is how panels, facings and fills are actually specified.

The panel removes energy at its resonance and again above the fill’s diffusion corner. Amount scales the absorption itself, so at 0 % the plugin is bit-transparent rather than a mix, and the response stays monotonic as you sweep it. In Absorb mode nothing in the chain can ever boost.

Panel bank and special effect

• Panels (1–4) puts that many panels in series; Edit chooses which one the Cavity / Air Gap / Facing Mass / Flow Resist sliders drive. Amount, Bypass and the CC routing are shared (CC 1–5 drive panel 1). The plot shows the combined curve with a numbered marker per panel’s resonance, so a bank tuned across the spectrum becomes a set of physically-shaped notches.
• Mode: Ring flips each panel: where it would absorb, it resonates, with the same frequency and depth but capped at +9 dB per section. A swept Ring bank is a pitched, vocal sort of phaser; a swept Absorb bank is a moving notch comb.
• Sweep flexes every panel’s facing mass with an LFO (resonance moves by up to ±1 octave at 100 % depth). Panels sit a quarter cycle apart, and Stereo Offset puts the right channel up to half a cycle away from the left. Depth 0 is a static panel.
• Sync locks the LFO to the host tempo and song position (division from 1/16 to 4 bars, default one bar). While the transport plays the sweep position is read from the song, so loops and rewinds stay locked; when stopped it keeps running at the tempo-derived rate. A host that provides no tempo falls back to Sweep Rate.

Parameters

The panel reports the derived total depth, resonance, Q, peak absorption and fill diffusion corner, and they update live as the geometry moves.

Drift routing

Route Drift’s MIDI output to Treatment’s MIDI input. With default settings CC 1 → Amount, CC 2 → Cavity, CC 3 → Air Gap, CC 4 → Facing Mass, CC 5 → Flow Resist. CC 1–4 are Drift’s default lanes; each control’s CC number is a dropdown in the panel and off disables that override. CC Channel selects which MIDI channel is listened to.

Randomise

Draws a new cavity, gap, facing mass and flow resistivity from the seed, rounded to values someone would actually pick. It advances the seed so a second press differs, and it is reproducible from the seed alone. Amount and Bypass are left alone, so randomising mid-performance does not change how much treatment you have.

Status

Core DSP, deterministic tests, the VST3 target, the panel and the catalog screenshot are complete. Host validation in REAPER is pending.