Mixing: What Is Gain Staging & Why Is It Important?


If you've been mixing for a while, you've likely heard of gain staging (that's why you've come to this article). The idea of gain staging has been around for a long time and continues to be an effective practice for achieving great, consistent results in both analog and digital recording and mixing.

What is gain staging, and why is it important? Gain staging is the process of feeding each audio device in a signal chain with optimal levels to avoid distortion or poor signal-to-noise ratios. In mixing, gain staging has added benefits of upholding proper headroom, “standardizing” track levels at given fader levels and helping with A/B tests.

In this article, we'll discuss gain staging as a practice and why it's so important when mixing music and audio.


What Is Gain Staging?

As mentioned, gain staging is the process of feeding each audio device in a signal chain with the optimal signal level.

Gain staging (in audio engineering) has been around, effectively, since the dawn of electrical recording (the 1920s).

Proper gain staging is necessary in the analog realm to achieve the best signal-to-noise ratios possible while avoiding distortion.

While noise isn't a major concern in modern digital environments, gain staging is still hugely beneficial in getting the best mixes possible today.

One example to raffle off is that mic level signals should be sent to mic level inputs, and line level signals should be sent to line level inputs.

In this example, sending a [lower-amplitude] mic level signal to a [higher-amplitude] line level input would cause significant noise. Because the line level input is expecting much higher signal levels, the input gain stage won't be able to apply nearly as much gain, and the gain that is applied is liable to increase the noise floor (along with the signal level) while also introducing its own noise to the audio.

On the flip side, sending a [higher-amplitude] line level signal to a [lower-amplitude] mic level signal is likely to overload the input. Because the mix level input is expecting much lower signal levels (it's not optimized to accept line level), we will very likely overload the circuitry and cause significant distortion.

The mic and line level example is my preferred way to explain gain staging and is important to consider when it comes to recording music.

However, for this article, we'll focus our efforts on mixing, looking at different inserts and processors and how gain staging works with each of them.

For more information on inserts, check out my article Audio: What Are Inserts? (Mixing, Recording & More).

So let's take a hardware compressor as another example. The compressor will likely have a “sweet spot” input level where its circuitry will perform optimally. Many analog units will be designed and calibrated to perform their best at a set nominal/average audio signal level. This is often defined as 0 VU (Volume Units), typically calibrated to +4 dBu in professional analog equipment.

Of course, audio signals are typically dynamic (pure tones aren't very musical), so there will be variations in signal level. This variation often goes up to or above the “sweet spot” and, of course, below it. The idea here is to drive the unit, the compressor in this example, near or at its optimal level.

Driving the compressor too hard will cause distortion as the circuitry is overloaded. Conversely, driving the compressor with too weak of a signal will cause poor performance as the sidechain/gain reduction circuit will have a harder time reading with low-level control signals. Furthermore, the noise introduced by the circuitry will be relatively high compared to the signal level.

There are some instances where driving a processor “into the red” above the 0 VU mark sounds great. With professional analog audio, the maximum level is often set at +24 dBu, giving us about 20 dB of headroom above 0 VU (0 VU roughly equals +4 dBu). The harmonic saturation resulting from driving an analog processor above 0 VU (but below clipping the maximum) can yield sonically-pleasing outcomes.

We can drive the audio device with appropriate signal levels by adjusting the signal level sent to it. In this example, if the compressor is first-in-line, we'll rely on the gain of the channel strip (the volume fader is post-inserts). If the compressor is inserted after another processor, we'll set that processor's output level to send the appropriate signal level to the compressor.

Sticking with our compressor example, it's then on us to set an appropriate amount of makeup gain to ensure the compressor's output signal level is right for the next insert (if applicable), such as an EQ, for example.

Note that while track faders are post-inserts, we can effectively use track faders to control the signal level feeding the buses within a mix. Make sure you understand the signal flow before going about gain staging any processors in the mix session.

Now that we understand the basics of gain staging with analog equipment, it's worth considering its role in digital systems. While noise isn't a major concern in modern digital environments, gain staging is still hugely beneficial in getting the best mixes possible today.

Although many plugins can work well and sound great at a variety of different levels, there are some plugins–particularly those that emulate analog hardware–that do have “sweet spots” and will sound worse when driven too low (noise) or too high (distortion).

The hard maximum for digital audio is 0 dBFS (decibels full scale).

Although there's no set standard, we can assume either -18 to -20 dBFS as the nominal level for digital audio. Remember that it's the “optimal level”, so maintaining an average of -18 to -20 dBFS is recommended but not necessarily crucial.

To give more context to the -20 dBFS recommendation, we can look at the typical +24 dBu analog clipping point and the hard 0 dBFS digital clipping point. If we match these clipping levels and take +4 dBu as our nominal level, we have 0 VU = +4 dBu = -20 dBFS.

With this information, being “in the red” in the digital realm (when using plugins that emulate analog hardware, for example) would mean signal levels between -20 and 0 dBFS. Of course, many plugins will perform optimally at a wide range of levels. However, we should keep this in mind for those with level-dependent performance.

Refer to the specific plugin manual if you require such “sweet spot” information (if applicable).


Gain Staging In The Mix

Gain staging is important in both analog and digital mixing. Whether we're using an analog board or a digital audio workstation, we can benefit greatly from proper gain staging.

We've already discussed the proverbial “sweet spots” of analog equipment and how this translates to many digital plugins as well. Beyond minimizing noise and distortion, we should discuss the mix issues of headroom, standardized track levels, and equal loudness for A/B testing.

Gain Staging For Adequate Headroom

Let's begin with headroom. Headroom is effectively the difference between the maximum level of a given signal and the maximum level of the system.

The hard maximum in digital systems is 0 dBFS (even if we can monitor above that in 32-bit floating point). The maximum in most analog systems is about +24 dBu, which is 20 dBu above 0 VU.

So if we have a signal level that peaks at -20 dBFS in a digital system or +4 dB in an analog system, we'll have 20 dB of headroom.

Gain staging each individual track in a mix will help us prevent that track from exceeding the maximum of the system, giving us adequate headroom and preventing clipping distortion.

But this extends beyond the individual tracks. We must also ensure our buses and the mix bus don't clip either. These buses have multiple tracks routed to them and can quickly become overloaded if we aren't careful about sending proper levels.

Setting our gain staging to -20 dBFS (or 0 VU) at the track level is generally sufficient to avoid overloading our buses and mix buses. However, in denser mixes, we may need to bring our levels down further. In this case, I'd recommend setting lower fader levels to ensure we are still driving the track inserts properly (the inserts are pre-fader).

We'll discuss how to set up gain staging in the following section.

Maximizing loudness in mastering uses up this headroom, bringing the audio up in level without clipping it to make it competitive with other mastered audio. It's generally advised to leave some amount of headroom on the mix bus for mastering engineers to work with.

To learn more about headroom and buses in mixing, check out the following My New Microphone articles:
What Is Headroom In Audio? (Recording, Mixing & Mastering)
What Are Audio Buses? (Mixing, Recording, Live Sound)

Gain Staging For “Standardized” Track Levels

“Standardized” track levels, as I call them, are another big benefit of gain staging our mix.

By gain staging each track to the same level, we're not only able to drive our inserts optimally, but we also will find that when two tracks have faders at unity gain, they'll have the same approximate levels.

This, to me, makes mixing so much easier than having mismatched levels between our tracks.

For example, consider a kick drum, hi-hat, vocal and bass guitar. Before gain staging, we have the following levels with faders at unity gain (I'll use dBFS):

  • Kick: -8 dBFS
  • Hats: -30 dBFS
  • Vox: -20 dBFS
  • Bass: -12 dBFS

To get them balanced, we'd have to dial in the faders at a variety of different levels. At a glance, we wouldn't be able to see how each of these tracks is balanced by looking at the faders, as they'd be all over the place. Extend this across an entire mix, and things can get messy.

Furthermore, pre-fader sends will also become more difficult since we'll have to balance them according to different input levels for each track.

By gain staging correctly, we can have all the tracks at -20 dBFS when at unity gain. From there, we can easily see how the mix is balanced by looking at the faders. If a track's fader is relatively high, we'll know that that track is higher in the mix. Similarly, if a track's fader is relatively low, we'll know that that track is lower in the mix.

Gain Staging For A/B Testing

On the topic of matching our levels with gain staging, I also want to discuss the importance of A/B testing and ensuring equal loudness when A/B testing.

Put simply, A/B testing tests “thing A” against “thing B” to decide which option is better.

When it comes to A/B testing during our mixes, the most common and obvious test is to turn plugins/processors on (A) and off (B) to hear whether they help the mix or not.

So just like we set an ideal level for feeding an audio unit, we must also be aware of that unit's output level and whatever processor is next in line.

While there are no set standards, it's most often the case that plugin sweet spots will be around -20 dBFS, and analog unit sweet spots will be around +4 dBu. So matching our processors' input and output levels is generally the best bet for gain staging throughout the mix.

Furthermore, level matching is vital for A/B testing as it removes the loudness bias. The loudness bias is our natural propensity to prefer the louder option, even if it's not necessarily the best choice for the mix.

So level matching with gain staging helps with A/B testing and with gain staging throughout the signal chain. It also gives us the benefit of being able to automate the on/off of a processor throughout the mix without having unwanted jumps in signal level.

I talk about A/B testing in greater detail and offer what I believe are the 5 most important A/B tests to begin incorporating in your mixes in this video.

To learn more about A/B testing, check out my article A/B Testing & Its Importance In Mixing (With 5 Best Tests).


How To Properly Gain Stage The Tracks In Your Mix

Now that we understand what gain staging is and its many benefits in the mix, let's go through the process to understand how to gain stage our mixes properly.

First, gain staging is not adjusting the faders so that all the tracks are the same level. Remember that gain staging happens throughout the signal chain, and faders control levels after the tracks' inserts.

Adjusting the faders is about balancing the mix, and while it's an essential part of mixing, it's not technically gain staging.

Some people like using the clip gain of their tracks' audio files within the mix to achieve gain staging. This can be effective since it alters the levels before the tracks' inserts and even makes the audio waveforms look more uniform across the session.

However, we can only do this in channels that have audio (no buses, effects returns, etc.), and it can take longer to do than the method I would suggest.

Rather, when it comes to teaching gain staging, I always suggest utilizing a gain or trim plugin (or an analog channel's gain control) as the first insert to adjust the signal gain of whatever type of channel we're working with.

Furthermore, suppose we're dealing with processors that don't offer easy control over their output levels. In that case, we can also insert a gain/trim plugin immediately after and control the “output” that way before whatever else comes in line.

I'll be discussing the gain staging process as if we're using a DAW, though I'll use parentheses for analog gain staging as well).

Gain or “trim” plugins can be found stock in any digital audio workstation (channel gain controls are commonplace in analog mixers).

When it comes to gain staging, we'll start before we ever start touching faders to balance the mix. With all faders at unity gain, we'll insert a gain/trim plugin on each track.

Play the mix back and set the gain so that each track hits an average of about -20 dBFS (or +4 dBu in analog systems). When dealing with tracks that have wide dynamic ranges, you may want to err on the conservative side and hit -20 dBFS at the climax or, alternatively, hit higher at the climax to push processors into the red once you start processing.

Once each track is gain staged, go about getting the balance with faders and mix the material.

If you'd prefer a video, I have one dedicated to gain staging and its importance before mixing. Check it out here:

I hope that's been helpful. Gain staging is pretty straightforward, yet its power should not be underrated as a pre-mix process (and a process during mixing). If we want the best performance from our processors, an easy way to see the fader balance and A/B, and more consistency throughout our mixes, gain staging is an excellent first step to take!


This article has been approved in accordance with the My New Microphone Editorial Policy.

Arthur

Arthur is the owner of Fox Media Tech and author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or composing music for media. Check out his Pond5 and AudioJungle accounts.

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