Using the Reaper Post-Fader System with Fiedler Audio Dolby Atmos Plugins

In the previous post, I introduced a custom script and JSFX plugin system designed to mimic post-fader inserts within Reaper. Now, let’s look at a practical and important application: using this system with object-based immersive audio workflows, specifically with the popular Fiedler Audio Dolby Atmos plugins.

(If you haven’t installed the Post-Fader system yet, please refer to the previous post/video for instructions and download links from the AudioIdeas GitHub Repo).

This video demonstrates how to integrate the Fiedler Audio Beam plugin correctly using the post-fader setup:

The Challenge: Atmos Beam and Pre-Fader Levels

When working with Dolby Atmos in Reaper using the Fiedler Audio plugins, you typically place the Dolby Atmos Beam plugin on tracks designated as objects. This plugin handles panning and sends the object’s audio data to the main Dolby Atmos Composer plugin (usually on the master track or a dedicated bus) for rendering.

The problem arises when Beam is used as a standard, pre-fader insert. Adjusting the track’s volume fader only affects the level going to Reaper’s main stereo output, if anywhere. It does not change the level of the audio object being sent from Beam to the Composer/Renderer. This makes the track fader effectively useless for controlling the object’s level within the Atmos mix, forcing you to rely solely on automation within the Beam plugin or input gain adjustments.

The Solution: Applying the Post-Fader System

Our custom Post-Fader Insert system solves this elegantly. By placing the Beam plugin between the Post Fader Start and Post Fader End JSFX plugins, we ensure its input level directly follows the track fader.

Here’s the step-by-step:

1. Activate the Script: Make sure the background script is running. Go to Actions > Show action list..., find Script: AudioIdeas_Post Fader volume control.lua, and click Run. (You only need to do this once per Reaper session).
2. Set Up Your Object Track: On the track you intend to use as a Dolby Atmos object:
   • Insert JSFX: AudioIdeas Post Fader Start.
   • Insert the Fiedler Audio Dolby Atmos Beam plugin. Configure its object settings as needed.
   • Insert JSFX: AudioIdeas Post Fader End.

That’s it! Now, when you move the track fader (or use volume/trim automation), the Post Fader Start plugin adjusts the gain before the Beam plugin. Beam receives the correctly leveled signal and sends the object to the Atmos renderer at the level dictated by your fader. The Post Fader End plugin ensures the track’s direct output level (if used) remains consistent with the fader position.

Workflow Tip: Save as FX Chain

Since you’ll likely be setting up multiple object tracks, it’s highly recommended to save this three-plugin sequence as a Reaper FX Chain:

• Select all three plugins (Post Fader Start, Beam, Post Fader End) in the track’s FX window.
• Go to FX > Save FX chain... (or use Cmd/Ctrl+Click drag).
• Give it a descriptive name like “Atmos Object Post-Fader”.

Now you can instantly add this entire calibrated setup to any new object track.

Conclusion

This specific application demonstrates the power of the Post-Fader Insert script system for integrating complex plugins like the Fiedler Audio Dolby Atmos Beam into a more traditional, intuitive mixing workflow within Reaper. It restores the expected functionality of the track fader for controlling object levels in an immersive mix.

Stay tuned for more use cases for this system! You can find the script and plugins at the AudioIdeas GitHub Repo.