DUBX User Guide

Feedback/VCA Bus Compressor · by GDP Audio · macOS & Windows

Download the PDF · DUBX product page · Release notes

Overview · Controls · Factory Presets · Support

Overview

DUBX is a bus compressor inspired by a classic American VCA compressor. It reproduces that classic feedback/VCA topology — fast, punchy gain reduction with program-dependent (auto) release — using a stereo-linked RMS detector, a fixed fast attack, an auto release that lengthens with the depth of gain reduction, and an optional soft knee.

System Requirements

Installation

macOS

Run the DUBX macOS installer (the .pkg file you downloaded) and follow the on-screen steps. The installer places files at:

Windows

Run the DUBX Windows installer (the .exe file you downloaded) and follow the on-screen steps. The installer places files at:

Most DAWs find DUBX automatically on their next plugin scan. If it doesn't appear, rescan plugins from your DAW's plugin manager.

Licensing

DUBX runs in demo mode until a license is activated. In demo mode a brief noise burst plays approximately every 45 seconds — all controls remain fully functional.

To purchase a license visit gdpaudio.com.

To activate:

1. Click the UNLICENSED - CLICK TO ACTIVATE pill in the plugin footer.
2. Paste the full contents of your license file into the text box.
3. Click Activate. The pill will change to LICENSED TO followed by the name on your license.

Your license file carries the name it was issued to, and the pill shows it (shortened if it is long). A license that carries no personal name simply shows LICENSED. Either way it unlocks the plugin in full.

Your license is stored at:

Using another computer — activate DUBX there with the same license file. No internet connection is required.

Uninstalling

macOS — open DUBX Uninstaller.app from your Applications folder and follow the prompts.

Windows — go to Settings → Apps → Installed apps, find DUBX by GDP Audio, and choose Uninstall.

Both remove the plugin files and your user presets. Your license file is kept, so reinstalling DUBX later doesn't require re-activation.

Controls

THRESHOLD — Level above which compression begins. Range: −40 dB to 0 dB.

COMP (Ratio) — Compression ratio, from 1:1 (no compression) up to 20:1. Displayed as X.X : 1.

OUTPUT — Makeup gain applied after compression. Range: −12 dB to +12 dB.

SOFT KNEE — Toggles the soft knee. On = smooth transition into compression. Off = hard knee for a snappier, more obvious onset.

STEREO / MONO — Routing mode. STEREO processes L and R independently through the linked detector. MONO sums both channels before the detector and spreads the result to both outputs.

BYPASS — Hard bypass. All gain reduction is skipped.

GAIN REDUCTION METER — Analog-style needle meter showing the current amount of gain reduction, 0–20 dB.

DSP Signal Chain

Routing → Stereo-Linked RMS Detection → Threshold / Knee Comparison → Program-Dependent Auto Release → Gain Computation → Output (Makeup) Gain

The detector measures a short (~4 ms) RMS envelope of the summed L/R signal so both channels receive identical gain reduction — avoiding image shift on a stereo bus. Attack is fixed and fast (~2 ms), matching a feedback/VCA topology. Release is not fixed: it is program-dependent, stretching from about 60 ms up to 700 ms as the depth of gain reduction increases. This is what gives DUBX its “glue” character — small overshoots recover quickly, while heavier reduction settles more slowly instead of pumping.

Soft Knee

With SOFT KNEE engaged, DUBX blends into compression across a 10 dB window centered on the threshold using a quadratic curve. With SOFT KNEE off, the compressor uses a standard hard knee: no gain reduction below threshold, full ratio applied immediately above it.

The difference is deliberately subtle and is most audible when the signal hovers around the threshold; under heavy compression the two settings sound nearly identical.

Parallel Compression

DUBX is well suited to parallel (New York-style) compression: route a copy of a kick, bass, or drum bus to an aux track, drive DUBX hard (4:1–6:1, several dB of gain reduction), and blend the heavily-compressed signal back under the original. The uncompressed transient stays intact while the parallel path adds sustain and low-end weight. See the FAT LOW END, PARALLEL KICK, and PARALLEL BASS presets for a starting point.

Factory Presets

24 factory presets are included. Click the preset name in the plugin header to open a list of every preset and pick one directly, or step through them with the < and > arrow buttons. Presets you save yourself appear at the bottom of the same list.

User presets are saved to ~/Library/Application Support/DUBX/ (macOS) or %APPDATA%\DUBX\ (Windows). Use SAVE to store settings, RENAME / DELETE to manage them.

Support

Support: support@gdpaudio.com · Release notes: gdpaudio.com/dubx-release-notes

GDP Audio and the names of our products are trademarks of GDP Audio LLC. All other product and company names mentioned in this guide are trademarks of their respective owners. They are used only to describe the character of a sound or for compatibility, and do not imply any affiliation with, or endorsement by, those companies.