Why Proper Gain Staging Is Crucial To Any Mix
Gain staging is one of the most fundamentally important elements in creating a professional-sounding mix. Without proper gain staging, your mix may suffer from unwanted distortion or excessive noise. In this blog, we’ll explain the basics of gain staging and how it can be used to improve the sound of your productions.
What Is Gain Staging?
Gain staging is actually a pretty straightforward concept—it’s the process of optimizing the level at every point in your signal chain to ensure a clean, clear sound. If the signal is too loud, it may clip, causing distortion. If the signal is too quiet, you may capture unwanted noise, especially from analog hardware.
It may seem simple, but with hundreds of gain stages in every session, it can quickly become overwhelming. Let’s take a look at a typical vocal signal chain.
A vocalist sings into a condenser microphone, where the gain is adjusted using a preamp. If the singer is too loud, you can engage the pad on the microphone to lower the level.
From there, you may process the vocal with an equalizer and a compressor before routing the signal through your console and capturing it on a tape machine. You may even send the signal to additional signal processors like reverb or delay and blend the returns in with the original on the mix bus.
Between all the inputs and outputs in that signal chain, that’s over a dozen gain stages just for a single vocal track—not to mention the rest of the tracks in the session. Unwanted noise can build up quickly with every link added to the signal chain. That’s why it’s so crucial to make sure you use proper gain staging to eliminate any unwanted noise.
To dial in the right amount of gain, you need to find the sweet spot in the signal-to-noise ratio, which measures the amount of noise in any given signal.
Analog circuits generate a small amount of noise, which acts as the “noise floor” of your track. In order to be heard clearly, the signal needs to be louder than the noise floor at all times. To achieve this, increase the input gain.
Just be sure to leave a little bit of “headroom” to prevent clipping. Headroom is the amount of space between the loudest part of your track and the point where clipping occurs.
So how loud should you strive to set each signal when recording or mixing? Well, that depends on the type of equipment you’re using.
Analog vs Digital Clipping
Arguably, one of the biggest differences between analog and digital recording is the way each system handles clipping. In the analog domain, clipping can actually create a very pleasant sound. Many engineers are familiar with the idea of “driving” an analog circuit, intentionally creating saturation or distortion to thicken up a sound or help it cut through the mix.
Increasing the input level too high causes the circuit to clip the signal. In the analog domain, this generates harmonic distortion that often enhances the sound of a track in small (or even large) amounts.
But in the digital domain, clipping almost always sounds terrible. Even if your track just barely pushes the meters into the red—in most cases, you’re introducing harsh digital artifacts into your mix. This is because digital algorithms are not able to replicate a signal above a certain point.
In order to properly measure the level of your tracks in both the analog and digital domains, you need to understand the difference between dBu and dBFS.
The dBu Scale
A decibel is a unit of measurement that’s used to measure many different things. Much like a “degree,” what you’re actually measuring depends on the scale you use.
dBu stands for decibel units which are used to measure the amplitude of analog audio signals. Based on the “volume unit” scale used in VU meters, the dBu scale is calibrated so that +4 dBU equals the nominal operating level of professional audio equipment—also known as 0 VU. Whether you’re dialing in the gain for a preamp, the input for an analog compressor, or the record level on your tape machine, +4 dBU is the ideal level.
Professional analog audio equipment typically begins to clip around +24 dBu, which means that even signals with loud transients like kick or snare drums shouldn’t cause clipping. Most tracks will peak around +12 dBu, giving you at least 12 dB of headroom before introducing distortion.
Most analog audio equipment has a noise floor of about -95 dBu, meaning you must ensure your signal is above this level at all times to remain audible.
The dBFS Scale
dBFS stands for Decibel Full Scale and measures the amplitude of audio signals in the digital domain.
Unlike the dBu scale, clipping occurs at the exact same point on all digital systems; 0dBFS. A signal cannot exceed 0dBFS— when you see a red "clip alert" at the top of your meter, that’s your DAW telling you it failed to recreate audio and is spitting out a garbled digital message instead.
That’s why it’s so important to make sure every track has plenty of headroom. The nominal recording level for digital signals is -20 dBFS, which is equal to +4dBU or 0 VU in the analog domain.
Thankfully, you have a little more space in the digital domain. The average noise floor of a 24-bit conveyer is -119 dBFS, meaning you can record tracks at a much lower level without the risk of capturing unwanted noise.
When in doubt, it’s best to err on the side of caution and record at a low level—you can always bring up the level later, but you can never get rid of digital distortion.
How To Properly Gain Stage
Regardless of which domain you’re working in, it’s important to remember that proper gain staging is one of the many secret ingredients to professional sounding mixes.
To adjust signals in the analog domain, you’re limited to the controls of the device, such as faders or knobs. In the digital domain, you can adjust the clip gain of a track to reduce levels at the source or use channel faders for post-processing control.
Most plug-ins feature dedicated input and output controls, but for those that don’t, you can use a trim control plug-in to manually adjust the levels of a track at any point in the signal chain. When in doubt, it’s always best to check your mix with a dedicated metering plug-in like LEVELS to help you identify any issues in your mix.