Historically, with analogue recording, it was often necessary to set input levels as high as possible so the signal is just below (or sometimes exceeding, for effect) the maximum level that the recording medium (e.g. tape) can handle. This is done to try to offset the fact that tape has a fairly low signal-to-noise ratio, so quiet recordings can lose some detail as the track gets buried in ‘tape hiss’.
For example:
- Good quality tape machines tend to have a signal-to-noise ratio between 60-70dB.
- A Scarlett 2i2 2nd Generation interface has a dynamic range of 106dB (A-weighted), with an Equivalent Input Noise measurement of -128dB (A-weighted).
In practice, in digital recording (particularly at 24-bit) trying to record as ‘hot’ as possible is not particularly necessary, and it can make your track more difficult to balance later on.
Digital clipping is undesirable and if multiple tracks are recorded close to the maximum digital level (0dBFS) then the sum of these tracks exceeds this, causing unwanted distortion.
I have to set the gain high to get a good input level
Many of our microphone preamps (for example the Scarlett and Clarett ranges) apply between +10dB and +60dB of gain to the input signal. The gain required to obtain an acceptable signal level will depend on several factors, including:
- The input source (A loud drum vs a quiet acoustic guitar)
- The type of microphone (some microphones are less sensitive than others)
- The distance between the mic and the sound-source.
For example, signals with a high sound pressure level (SPL) like those from acoustic drums and guitar amplifiers aren't likely to require much amplification; it's normal to set the gain on the lower range. This is particularly true if a sensitive condenser microphone is utilised.
Quiet signals such as vocals or and acoustic guitar will require more amplification, particularly if used with a dynamic microphone or if the microphone is further from the source.
When you move the gain control, the gain change isn't linear, it is not consistent around the whole dial. Therefore, it is not unusual to require setting the gain at the high end of the dial's rotation to get a reasonable signal level.
What is gain staging?
The common misconception is that we should record all tracks as loud as possible. And, when mixing, try to get the peak level on our master buss as close to 0dBFS (without actually hitting that point) as we can to end up with a ‘loud’ mix.
Recording at high levels tends to make mixing quite tedious. If the mix is almost 0dBFS already, and you decide you’d like to raise the volume of one track slightly, this single mix change can send your master into the red. Instead, you need to lower the volume of all your other tracks to compensate for this.
Gain staging is the act of ensuring 'healthy' levels throughout each stage of the recording and mixing process. Too low, and you're not using the full resolution of the recording medium, and you might run into noise issues, too high, and you run the risk of overloads.
If each track is recorded well, with a sensible microphone for the application and through a good quality microphone preamp, there is no reason to try to push 0dFBS at the recording or mixing stages.
Instead, when recording, aim for a more conservative level (e.g. peaking around -12dBFS).
Recording at a lower level means there is some headroom available should the musician play a loud note.
When mixing, aim for a similar peak level at your master buss. This makes it far easier to decide later if a track needs to be turned up– since you’ve left headroom available to do that.
Why do commercially produced mixes sound louder than mine?
The step that tends to add the greatest increase in ‘loudness’ comes after the final mix down, in the mastering stage. When mastering, it's common to use compressors/limiters to reduce the dynamic range of the track, meaning that the difference between the peak level and the lowest level is decreased, resulting in a higher ‘average’ volume.