Short-versionMixing ITB vs mixing on an analog desk has similarities, yet there are different princippels for each. Thus, you should not confuse one with the other.
Recording/ trackingWhen recording audio into your DAW, make sure you're never above 0dbfs on your AD-converters. In the 24-bit converter world, getting a too low input level is less an issue, so as long as you above let's say -35dbfs you're ok.
Practically speaking I recommend:
- Peak-levels: Between -30 to -6dbfs
- Rms-levels: Between -35 to -12dbfs
MixingReaper uses 64bit floating point as default for internal processing. This means practically unlimited headroom. So technically speaking, using plugins that handles this (like ReaEq), anywhere between -100dbfs to +100dbfs is valid.
Practically, this is not recommended for 2 reasons
- Metering, faders -range: Metering, knobs, faders and other visual aspects are made for typically -30 to 0dbfs usage.
- Saturation and plugin-clipping: Some plugins are made for a specific sweetspot, much like analog gear. And some will clip above a certain point.
- -18dbfs rms is the sort of modern industry-standard
- Some plugins have a higher sweet-spot. Variety Of Sound-plugins comes to mind
- And some are configurable for gain of your choice.
(unless specific other needs)
Master-bus/ renderingAlthough Reapers internal gain-structure may go far above 0dbfs, this is not the case when leaving the master-bus (or any hardware output). This is about:
- DA-converters for you monitoring
- Rendered output when mixing down your song for an wav/mp3 or similar
- Make sure you're levels are below -0,5dbfs peak on the master output
- It's often wise to have a limiter as last fx on you master-channel (eg. MGA JS Limiter). But, be aware if it's actually limiting the audio or not. Ceiling -1,2 to -0,5dbfs.
- You can use your limiter threshold to adjust your monitoring-levels.
Looking a little deeper
RMS vs. peakSo, what is rms dbfs vs peak dbfs?
RMS: Is an average value over a set time-frame. We often use 300ms. RMS is often similar to analog VU db.
Peak: Is an absolute value of the highest point of your wave-form.
ISP: Note that a signal may have a peak-value below 0dbfs, yet have an ISP (Inter sample peak) above 0dbfs.
Gain and fadersSo, where do you set your faders?
Well, if your recorded audio is about -18dbfs rms, then starting out with faders at 0db for tracks and buses is a good idea. Then, lower the ones that needs to be quieter in the mix.
This will result in a level on masterbus that's maybe somewhere around -12dbfs rms to -6dbfs peak.
Now, adjust the threshold of your master-fx limiter to -3 to -6db, and things should be stellar.
But what if your recorded audio is everywhere but -18dbfs rms?
Well, there are different solutions:
- Use pre-fx volume envelope/knob
- Use a gain-plugin (anything with a volume-knob will do)
- Use a sophisticated gain-plugin, like TBProAudio AB_LM vst
- Normalize audio (Action > "Normalize item")
- Or, don't care that much.
Myself I tend to go with a mix between aiming for -18dbfs rms for recording, and don't care that much when mixing. But, I'm considering changing to a -18dbfs rms mix gain workflow with pre-fx vol or something like TBProAudio AB_LM :)