Operating Manual
Dual-channel VCA Compressor / Limiter / Gate
The ThirtySix is a model of a classic early-’90s budget rack compressor — two identical channels, RMS or Peak detection, a hard/soft knee switch, and a downward gate on each side.
Every part of the sound is measured. The ratio calibration, the threshold law, the knee width, the two-stage attack, the release curves, the sidechain frequency weighting and the output noise floor were each captured from a real unit on a test bench, fitted, and then checked back against the hardware with real program material — not tuned by ear against a memory of how it should sound. It is a VST3 and Audio Unit effect for Windows and macOS, and an AAX effect for Pro Tools on Windows; there is no standalone build.
From the plugin page, Get It! asks for your system, then gives you one of two files:
| Windows installer | A signed .exe. One security prompt, then it places The ThirtySix.vst3 in C:\Program Files\Common Files\VST3\ along with this manual. If Pro Tools is installed, the installer also offers an AAX version for Pro Tools — tick Also install the AAX version for Pro Tools; it goes to C:\Program Files\Common Files\Avid\Audio\Plug-Ins\. Pro Tools picks new plug-ins up at its next launch. |
| macOS installer | A .pkg, signed and notarized by Apple, so it opens with no Gatekeeper warning. It installs The ThirtySix.vst3 into /Library/Audio/Plug-Ins/VST3/ and the Audio Unit, The ThirtySix.component, into /Library/Audio/Plug-Ins/Components/. For Pro Tools, tick the Pro Tools (AAX) checkbox (off by default); it installs The ThirtySix.aaxplugin into /Library/Application Support/Avid/Audio/Plug-Ins/. Universal: Apple silicon and Intel. |
| Portable zip | The raw bundles and the manual: the .vst3 on Windows, the .vst3 and .component on macOS. Copy them into your plug-in folders yourself (on macOS, ~/Library/Audio/Plug-Ins/… installs for your user only). |
Restart your DAW or rescan plug-ins, then load The ThirtySix as an insert effect. On macOS, Logic and GarageBand use the Audio Unit; other DAWs can use either.
Two of the checks, drawn against the unit they were fitted from. The black line is the real 3630; the blue line is the model.
Where it is loosest: the top of the Ratio dial (10:1 and up) is lightly sampled and drifts a few dB against a sustained tone — it barely moves on real program material, which is why it passed the listening test, but it is the part of the model held least tightly. The distortion character is approximate too; see Presets.
The ThirtySix has two independent compressor strips, A and B, each modeled on one measured channel of the hardware. The Mode switch decides how they are wired:
| Mode | Wiring |
|---|---|
| Dual | A and B are two separate processors. On a stereo track, strip A handles the left channel and strip B the right, each with its own settings — for treating a stereo pair asymmetrically, or running two unrelated mono inserts in one slot. |
| Stereo | Strip A’s controls drive both channels and the two sides share one detector, so the stereo image is not pulled around by level differences between left and right. The normal choice for a stereo bus. |
| Serial | The signal passes through strip A, then strip B — two stages of gain reduction in one insert. A slow, gentle leveler into a fast, hard catch, for instance. The “Serial – Driven Grit” preset is built this way. |
| Control | Range | What it does |
|---|---|---|
| Threshold | −40 to +20 dB | The level above which the compressor acts. The dial is marked in dBu, like the hardware’s, and the model’s law is anchored to real voltage — a given mark behaves like the same mark on the unit. 10 dB ticks. A fresh instance opens at a moderate −6 dB. |
| Ratio | 1:1 to 30:1 | How hard it compresses above threshold. The printed scale is deliberately not evenly spaced — the knob crowds toward the top exactly as the panel does — so a small move near the top is a big change. Past roughly 10:1 it is effectively limiting. |
| Attack | 0.1 to 200 ms | How fast gain reduction engages. The real unit’s attack is two-stage: it grabs about a third of its gain reduction in under a millisecond, then settles over ~24 ms. The model runs both stages, so a fast setting catches transients cleanly instead of over-squashing and pumping the way a single-pole attack does. |
| Release | 50 ms to 3 s | How fast gain recovers once the signal drops below threshold. The fast end of the dial is the least tightly sampled part of the model — the shipped values are sound but not pinned as hard as the mid-range. |
| Output | ±20 dB | Make-up / output trim after compression. It also drives the modeled noise floor: the hiss climbs as you push Output, exactly as the hardware’s does. |
| Soft Knee | on / off | Off: a firm bend into compression (measured at roughly a 12 dB knee). On: a wide, gradual knee (~30 dB) — the transition starts well below the threshold mark and eases in. |
| RMS Detect | on / off | Off (Peak): faster, transient-aware detection, carrying the unit’s measured sidechain emphasis around 40 Hz–1.6 kHz. On (RMS): slower, level-averaged, flatter-weighted — smoother on sustained material. |
| Bypass | on / off | Takes the compressor stage out of that strip (the hardware’s COMP/BYPASS switch). The gate and the output stage still run. |
| Gate Threshold | OFF, then −45 to −10 dB | Downward gate. Fully counter-clockwise is OFF — a detent, the gate does nothing. Turn it up and signal below the set level is attenuated. The value scale is uneven, matching the panel. |
| Gate Rate | 20 ms to 2 s | How quickly the gate closes and reopens. |
The small switch under each level ladder chooses whether that ladder shows the strip’s input or output level. It is a display choice only, is not automatable, and is saved with the session.
| Mode | Dual / Stereo / Serial — see above. |
| Noise | 0–200 %. Adds the measured 3630 output-noise floor: a warm, band-tilted hiss, decorrelated between the two channels, that gets louder as the compressor works and as Output comes up. 0 is a clean path. The curve is a measured 12-point sweep of the real unit — very quiet at low Output (as the hardware is), coming forward as you push the output stage. This is where the unit’s “noisy” reputation lives, so it is off by default and yours to dial in. 100 % is the real unit’s measured level, which is honestly quiet; above that it is deliberately exaggerated, climbing to 30 dB louder than the hardware at 200 %, for when you want the hiss plainly audible. (Sessions saved before version 1.2.3 keep the old 0–100 % scale, where 100 % was the measured level, so they sound exactly as they were mixed.) |
| Gate Link | The small chain button between the two gate sections. On, the lower gate (Channel B, or Stage 2 in Serial) follows the upper one’s Threshold and Rate, and its own knobs dim. On a stereo track in Dual or Stereo mode both sides also open and close together, so the image doesn’t wander. Off, each gate uses its own settings again; linking never overwrites them. The hardware’s gates can’t be linked — this one is a convenience. |
| External Sidechain (Comp) | Keys the compressor(s) off the plug-in’s Sidechain input bus instead of the signal itself. Route another track to that bus in your DAW to duck this one. |
| External Sidechain (Gate) | The same, for the gate(s), off an independent Gate Sidechain bus — so a gated-reverb style patch can trigger the gate from a dry source while the compressor keys normally. |
Presets are grouped — Bus & Master, EDM, Drums, and so on. Two notes worth having:
The model will keep improving. So that a better model never moves a mix you have already finished, the plug-in stamps the current model version into your saved session, and on reload it runs that version — not the newest one. A fresh instance always opens on the latest.
This follows the Six Walls version rule: 1.0 means recall is stable. An update will not change how an existing project sounds without pinning the old behavior behind a version switch. Start a new project on a new version; finish the ones you have open on the version they were built with.
| Plug-in doesn’t appear | Rescan plug-ins in your DAW. Confirm the file is at C:\Program Files\Common Files\VST3\The ThirtySix.vst3. Some DAWs keep a blocklist — check that too. |
| No gating | Gate Threshold sits at OFF (fully counter-clockwise) by default. Turn it up. |
| Sidechain preset not ducking | The external-sidechain presets need a source routed to the plug-in’s Sidechain bus in your DAW. Check the routing, and that External Sidechain is lit. |
| Sounds squashed on a new instance | The default Threshold is a moderate −6 dB, but a hot input into a low ratio still works hard. Raise Threshold or lower Ratio. |
| Hiss with Noise up | Intentional — it is the modeled output floor and it tracks the Output knob. Set Noise to 0 for a clean path. |
| SmartScreen warning on the installer | The installer is code-signed (publisher Edwin Jones), but a fresh certificate takes time to earn SmartScreen reputation. Click More info → Run anyway. |
| Format | VST3 (Windows) |
| Channels | Two modeled strips — Dual, Stereo-linked, or Serial |
| Detection | Peak (measured ~40 Hz–1.6 kHz sidechain weighting) or RMS |
| Knee | Hard (~12 dB) / Soft (~30 dB), measured |
| Attack | Two-stage, measured (0.1–200 ms dial) |
| Gate | Per strip, own threshold & rate, optional Gate Link; independent external key bus |
| Noise | Measured output-floor curve vs Output; 0–200 %, off by default; 100 % = the measured level, 200 % = +30 dB |
| Recall | Session stores its model version and replays it |
| Maker | Six Walls |
The measurement and modeling method is written up in docs/MODEL.md in the source repository.