TRUNKRTL User Guide

808 / Sub-Bass Designer · by GDP Audio · macOS & Windows

Download the PDF · TRUNKRTL product page · Release notes

Overview · Controls · Factory Presets · Support

Overview

TRUNKRTL gives your 808s and sub bass more weight, grit, and punch. Put it on an 808 or bass track: it finds the note you're playing, adds weight and harmonics so the low end comes through even on phone and laptop speakers, saturates it in four characters, tightens and monos the bottom, ducks it under your kick, and can even make it rattle like a car trunk. CAR CHECK lets you hear the track as if it were playing in a car.

System Requirements

Installation

macOS

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

Windows

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

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

Licensing

TRUNKRTL 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 TRUNKRTL there with the same license file. No internet connection is required.

Uninstalling

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

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

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

Controls

TAPE / 12-BIT / TUBE / CLIP — CHARACTER: the flavor of DRIVE. TAPE is warm and round with a soft top. 12-BIT is gritty and aliased (lower bit depth and sample rate, the classic sampler sound). TUBE is thick and adds even harmonics. CLIP is hard, loud, and flat-topped.

SUB — Weight. Up to 50% it boosts the 808's fundamental (up to +6 dB, following the note, glides included). Above 30% it also adds upper harmonics made from the sub, so the 808 is still heard on small speakers that can't play the low note itself. Range: 0–100%.

DRIVE — How hard the CHARACTER saturates. Level-matched: turning it up adds grit, not just volume. At 0% the sound is untouched. Range: 0–100%.

PUNCH — Hit versus tail. Turning it up brings out the attack of each note (up to +9 dB) and holds the tail steady, so the 808 knocks and sits at an even level. A steady sound is left alone. Range: 0–100%.

TIGHT — Cleans up the bottom. The low cut rises from 20 Hz to 45 Hz, removing rumble you can't hear but that eats headroom, and boomy low mids around 250 Hz are tamed (up to −5 dB). Range: 0–100%.

MIX — Dry to processed. 100% (the default) is fully processed; lower it for parallel processing. The dry signal stays time-aligned. Range: 0–100%.

MONO BELOW — OFF / 80 / 120 / 200 Hz. Everything below the chosen point is made mono, so the low end hits the same on every system and in clubs. Above it, the stereo image is kept. Default: 120 Hz.

DUCK — OFF / LIGHT / HEAVY. With your kick on TRUNKRTL's sidechain input, the 808 dips each time the kick hits (about 6 dB on LIGHT, 14 dB on HEAVY) and comes straight back up. The panel shows NO SIDECHAIN in red when DUCK is on but nothing is routed to the sidechain.

RATTLE — Click the button to switch the trunk rattle on or off; drag the bar inside it for the amount (0–100%). It adds the buzz of a trunk lid, panels, and plates shaken by a loud sub. It follows the 808: loud notes rattle, quiet ones don't. RATTLE is part of the sound: it's saved in presets and goes into your bounce.

CAR CHECK — Listening only: hear the track as if it were playing in a car (cabin boom on the lows, small-cabin resonances, a softer top, a little road noise, narrower stereo). It is never saved, is always off when the plugin loads, and lights up while it's on so you don't bounce with it.

LOW END DISPLAY — Live spectrum of the output from 20 to 250 Hz, with the detected note in Hz, the low-cut area set by TIGHT (CUT), and the MONO BELOW point. XMAX lights when the built-in limiter is working.

OUT METER — Output peak level, left and right.

BYPASS — Bypass with a short crossfade. Follows the host's bypass and stays in time with the rest of your session.

DSP Signal Chain

TIGHT → PUNCH → SUB → DRIVE (CHARACTER) → RATTLE → MONO BELOW → DUCK → MIX → XMAX limiter → CAR CHECK (listening only)

TRUNKRTL tracks the 808's note on its input, so SUB always boosts the note that's playing, even through glides. DRIVE runs oversampled, so its harmonics don't fold back as harshness; the exception is 12-BIT, which aliases on purpose like an old sampler. The last stage, XMAX, is an always-on look-ahead limiter that catches the biggest sub peaks and keeps the output under 0 dBFS. It only acts on hot peaks.

Oversampling and the limiter's look-ahead add about 3 ms of latency, which TRUNKRTL reports to your DAW so it can compensate automatically.

Ducking Under the Kick

Insert TRUNKRTL on the 808 or bass track, then use your DAW's sidechain routing to send the kick to TRUNKRTL's sidechain input, and choose LIGHT or HEAVY. The sidechain is only used by DUCK; everything else works without it. If DUCK is on and the panel shows NO SIDECHAIN, the kick isn't reaching the sidechain input yet.

Getting the Most Out of It

Start from a preset that describes the job (PHONE SPEAKER FIX, KICK MAKES ROOM, MONO SAFE), then adjust SUB and DRIVE by ear. Check the result with CAR CHECK, and on small speakers, where the harmonics from SUB do the work. If the low end feels loose, raise TIGHT before lowering SUB.

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/TRUNKRTL/ (macOS) or %APPDATA%\TRUNKRTL\ (Windows). Use SAVE to store settings, RENAME / DELETE to manage them.

Support

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