A VU meter embedded in a Reaper track control panel, along with the settings used.
I’m a bit confused about conflicting advice I keep seeing about gain‑staging. Some people say to adjust the gain until the sound sits at ‑6dBFS, and others say ‑18dBFS. And then others say it doesn’t really matter at all any more, as long as you’re not clipping at the audio interface. Is there a right answer?
Jake Bowen, via Facebook
SOS Reviews Editor Matt Houghton replies:I’m not surprised you’re confused because all those statements could be right! The first thing to say — and I’m going to assume you’re working in a DAW here, rather than entirely in the analogue domain — is that the considerations for recording and for mixing can be slightly different. When recording, the bottom line is that you need to ensure you’re capturing a healthy signal (relative to the noise floor) without clipping your interface’s converters. Ensuring the peak signals hit around ‑6dBFS will certainly do that, but 6dB isn’t a huge amount of headroom, and as long as you’re recording through 24‑bit conversion (never mind 32‑bit), you don’t need to sail so close to clipping; the noise floor will be low enough that you can leave more headroom. In this context, the ‑18dBFS figure you mention would refer to an average (RMS) level, rather than the peak. The idea being that this leaves almost as much headroom as professional analogue gear does — which means you just don’t need to think about the peaks.
Let’s turn our attention now to mixing in your DAW. Assuming the DAW is operating with 32‑ or 64‑bit floating‑point processing, you won’t clip anything while working inside the DAW. So, on a purely technical level, gain‑staging inside the DAW is unnecessary — as long as the levels on channels routed to your physical audio interface outputs never exceed 0dBFS. (Even True Peak meters aren’t perfectly precise, so it’s good to keep at least a dB or two in hand there).
There are practical reasons why it’s good to be disciplined about the signal levels in your DAW.
Yet, there are still some practical reasons why it’s good to be disciplined about the signal levels inside your DAW. For example, if your signal levels are all over the place, then your DAW’s meters won’t serve any useful purpose. If you want to bypass plug‑ins to A/B compare with the unprocessed sound, or to swap out and compare different insert effects/plug‑ins, it’s handy to be able to do so without having to compensate for level differences every time. And if you’re working with plug‑in processors with a fixed threshold or that model the non‑linear behaviour of analogue gear, they might need the input signal to be at or around a particular level if you’re to get the intended results from them.
In this context, there’s little point thinking in terms of the sample peak levels — each process has the potential to change a signal’s peak level pretty dramatically, so matching output peak levels to input ones isn’t helpful. Better, if possible, to set your DAW meters to an RMS mode, or use a dedicated VU meter calibrated so that 0VU is indicated at ‑20, ‑18 or ‑16dBFS. Unless you’re integrating hardware gear into your system, it doesn’t much matter which figure you pick as long as you’re consistent. I configured my Reaper system with VUs on every channel, and set the 0VU reference to ‑18dBFS, with a peak LED at ‑6dBFS.
For a deeper dive into this topic, check out the in‑depth article I wrote back in SOS September 2013, which is free to read on our website (https://sosm.ag/gain-staging-in-your-daw).