Every so often I discover a plugin that’s really different in a useful way. So the Luveler plugin is one.
The LUveler VST/LADSPA plugin is one such. Most of the limiters I have access to, use RMS level as the reference for setting the threshold. LuVeler is built to address the LU loudness scale, which is a modern ‘intelligent’ replacement for RMS level when calibrating loudness.
The cool thing about it for me is that you can set a floor, below which the input signal is left intact. Above that level it applies leveling to a target LUFS level.
A good discussion about LUFS vs other loudness measurements: What Are LUFS? The Complete Guide
I do mastering as a sideline, though I don’t promote that aspect of my practice as well as I might. But the Luveler is a good, free way to work on pre-mastering your own music.
Specific to Rack, even though most people’s go-to mixer, Mindmeld Mixer does a good job of soft-clipping overloaded signal, but if you really care about how your track sounds (and to leave some room for a mastering engineer to do their work) then you’ll mix so your stereo recordings have a fair amount of headroom.
My personal approach is to mix so that even the occasional stray peaks stay well below 0dbFS. That means that in order to sound ‘finished’ when compared to the usual standard levels for commercial release, you need to increase volume, and to some extent apply limiting to peaks. Even for pre-mastering - where a mastering engineer will eventually work on the final version for release - you want to get a healthy level, not to far off of broadcast standard.
My own standard is to pick the loudest section of a track, and adjust the limiting of that loudest section is -14LuFS and the True Peak never exceeds -1dB. That sounds, to my ears, close enough to finished to share with other people, but still leaves room for mastering.
Luveler makes it easy to achieve that kind of pre-master leveling. You have to add a LUFS meter after Luveler, since it doesn’t have it’s own metering. I use the MLoudnessAnalyzer, which is part of the MeldaProduction VST suite.
Since Luveler doesn’t affect audio signals below a set floor, it can be very transparent. It does enough limiting to sound good, but mostly it’s simply passing through the input, with a linear gain transformation.