DAW gain-staging

From time to time newbies and more advanced users are confused and ask about gain-structure for mixing ITB (In The Box). Here I'll walk through the subject, first the short version, then looking a little deeper. I'll use Reaper as my example, but most points are valid across the board of DAWs

Short-version

Mixing 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/ tracking

When 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

Aiming for -18dbfs rms is a good practice.

Mixing

Reaper 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.

Advice: Aim for a gain-flow around -18dbfs rms
(unless specific other needs)

Master-bus/ rendering

Although 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

I'll not dwelve into mastering here, just  recommend:

• 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. peak

So, 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 faders

So, 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 :)