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Six Walls

Free Alesis 3630 plugin
VST3, AU & AAX

The ThirtySix™

A dual‑channel VCA compressor, limiter, and gate after the Alesis 3630 (unofficial), one of the cheap black boxes that filled home‑studio racks a generation ago — modeled the slow way, from bench measurements of a real one. Free for Windows and macOS.

The ThirtySix plugin UI running the Drum Bus - 2-Stage preset in Serial mode: a Six Walls header with a preset selector and a Dual / Stereo / Serial mode switch, two stacked stage rows (STAGE 1 and STAGE 2) each with threshold / ratio / attack / release / output knobs over lit gain-reduction and input-output LED ladders, PEAK/RMS, hard/soft knee, input/output and bypass/comp switches, a gate threshold and rate pair with OPEN/CLOSE LEDs, a global noise knob, and COMP SC / GATE SC sidechain toggles
Before you download Six Walls is one person building these in his spare time and giving them away.

The Windows installer is code-signed — verified publisher Edwin Jones. A fresh signing certificate takes a little while to build reputation with SmartScreen, so for the first few weeks you may still see a “not commonly downloaded” note — click More info → Run anyway.

macOS: universal (Apple silicon + Intel), VST3, AU (Logic, GarageBand), and AAX (Pro Tools), signed with a Developer ID and notarized by Apple — it opens with no Gatekeeper prompt.
Watch It A quick introduction to The ThirtySix

A dual‑channel VCA compressor, limiter, and gate modeled after the Alesis 3630 — one of the cheap black boxes that filled home‑studio racks a generation ago, cost almost nothing, and ended up on a lot of records anyway. Not a clean compressor, and not trying to be: the point is the pump, the knee, and the two‑stage attack.

  • The compressor itself was measured on a real unit. Ratio calibration, threshold law, knee, the two‑stage attack, release curves, the sidechain frequency weighting, and the output noise floor were each captured, then checked back against the hardware with real program material.
  • Two channels, run as two independent processors, stereo‑linked, or in Serial (A → B) for two stages in one insert.
  • RMS / Peak detection, hard / soft knee, the full threshold / ratio / attack / release / output set, and a downward gate on each channel with its own threshold and rate.
  • Independent external sidechain buses for the compressor and the gate; a modeled output noise floor you can dial in or leave at zero.
  • Saved sessions stamp the model version they were mixed with and recall it, so future model updates never move a finished mix.

Hear it — dry vs. The ThirtySix

Each pair is matched for loudness, so you hear the compression, not a volume jump.

The pump · a 125 BPM loop

Mixed through The ThirtySix in a DAW. The dry version has the kick nudged up a touch.

Dry
Pumped
Drum bus · a dry studio kit

The Drum Bus – 2-Stage preset, rendered through the plugin itself.

Dry
Drum Bus
VST3 AU AAX Windows macOS JUCE 8 v1.2.4

Get It! downloads the Six Walls Installer, the easiest way to install The ThirtySix, keep it up to date, and hear about new releases. Prefer to install plugins one at a time? Every platform’s installers and zips are under Individual downloads on the Support page. Full manual on the Support page.

Questions about The ThirtySix

What is The ThirtySix modeled on?

The Alesis 3630 (unofficial), a classic budget rack unit with two VCA compressor/limiter channels and a gate on each. Both channels were measured on a real unit, and the model includes the hiss, which climbs as you push Output, just as the hardware's does.

What is different about this and the hardware?

Mostly convenience. The hardware already does Stereo, where channel A's settings drive channel B, and you can run Serial by patching A's output into B. Here those are a Mode switch with Dual, Stereo, and Serial, no cables required. On top of that, Gate Link ties the two gates together, the compressors and the gates each get their own external sidechain input, and you get presets, undo, and A/B.

How do I get a sidechain pump out of it?

Load one of the EDM Sidechain Pump presets, then route your kick to the plugin's Sidechain bus in your DAW. If External Sidechain isn't lit, or nothing is routed to the bus, it won't duck.

Can the gate be triggered from a different source than the compressor?

Yes. The gate has its own sidechain bus, independent of the compressor's, so a gated-reverb style patch can trigger the gate from a dry source while the compressor keys off the signal normally.

Is it really free, and what formats does it come in?

Free, no account, and no catch. VST3, AU, and AAX for Windows and macOS. The Six Walls Installer is the easiest way to get it and keep it updated, or you can grab individual installers from the Support page.

Disclaimer: Six Walls plugins are provided free of charge on an “as-is” basis — use them at your own risk, and always work on a copy of your session. Any comparison products are named for reference only; Six Walls is not affiliated with or endorsed by them.