Gain Structure: 6 Steps To Get The Best Results

Why Gain Structure is important

The discussion on audio levels, Gain Structure, Gain Staging, etc. is a recurring and occasionally heated topic. Many individuals, especially beginners, struggle with uncertainties and are often confused about how to set audio levels. My observations of discussions through videos, forums, and blogs reveal many differing opinions on the subject. Some sources have a wealth of information yet lack practical application, while others offer specific advice for specific scenarios or have inaccurate information. Additionally, the guidance often fails to provide practical strategies for consistency across varying situations that you, as an Audio Engineer, come across.

Gain Staging is crucial. As an Audio Engineer specializing in Front of House (FOH), Monitors, and Broadcast (Live Streaming), my conviction, based on extensive research and hands-on experience, is that there is a standard approach to setting correct audio levels, across all scenarios.

Setting correct audio levels is arguably the most important aspect of mixing, yet it is the least talked about and understood aspect. Two things will destroy your mix, bad performances and audio levels. It is difficult to have a great mix with bad performances and when gain levels are not consistent. Every mixing console and audio interface has a “Gain” knob. This is the first thing your audio hits as it enters the device. There is a reason why it is first. Get that wrong and you will have problems mixing effectively. If you can consistently get good audio levels, then you can mix on any console or DAW and in any venue.

You have probably have heard that gain levels don’t matter anymore in the digital world. That may or may not be true. Yes audio equipment is better now than they used to be, but I would argue that gain levels still do matter. If you understand why it matters and set a standard, your mixes are going to be better.

History and Technical Details

It’s important to understand the history and technical aspects of audio. Knowing why things are designed the way they are and how equipment works is crucial. If you know the design then you will be better off. While it’s said that there are “no rules” for music, it’s essential to know the rules before breaking them. Know how something works and you will have the “why” to back what you’re doing.

In our context, audio is classified into two groups, Analog and Digital. Analog records sound as continuous waveforms, while Digital translates sound into numerical data. Analog tends to make audio sound warm and natural, which is generally more pleasing to listen to. Digital maintains the fidelity of the audio source, providing an accurate representation of the audio.

There are various ways to measure audio. I am only going to cover dBu, VU, RMS, and dBFS. While there’s more information you can get into, these are the basics:

dBu stands for Decibels Unloaded

Line Level is measured in dBu (measuring voltage) and it was determined that +4dBu is the measurement to have enough voltage for audio to be at Line Level for telephone use and radio broadcasts. ¹²

VU stands for Volume Units

A VU meter is designed to measure audio to make sure the signal is at line level. Its response is similar to how humans perceive sound. VU meters are commonly found in studios, radio stations, and as plugins in DAWs. The VU meter was introduced in 1940 and standardized in 1942 for use in telephone installations and radio broadcasts. The 0 on the VU Meter, when calibrated, would indicate that the signal was at +4dBu (Line Level). This measurement was particularly useful when working on an analog console, where hitting around 0 dB on the console indicated that the audio was at or close to line level. ³ ⁴

RMS stands for Root Means Square

RMS measures the average volume over a period of time and is closer to how humans perceive sound. This measuring tool is commonly found in a DAW.

dBFS stands for Decibels Full Scale

dBFS stands for Decibels Full Scale. Metering in dBFS was introduced with the advent of Digital Audio. It measures how loud an audio sample is in relation to the full scale of what digital audio can handle. dBFS metering is found in all DAWs and most Digital Consoles.

Even though some of these tools were not initially created for musical use, they are still being used by professionals today. Understanding why they exist can be helpful.

How does it Relate to Gain Structure

How do these measurements relate to one another for Gain Staging? You have heard that the measurements I just mentioned, measure audio differently and serve different purposes. Therefore, you cannot use these measurements as a substitute for each other. This is partially true. Yes, you cannot use different tools interchangeably, but there is a relationship between all of them, and if you know how to read measurements, you can use them effectively.

0 VU = +4 dBu

As mentioned before, in our musical context, to determine if audio was coming in at Line Level, the audio needed to be +4dBu. A VU Meter was calibrated so that when the needle hit 0 VU, the audio source was at Line Level. But what if you don’t have a VU Meter? If you are using a DAW, there is most likely an RMS meter.

RMS and VU Meters

“But Sal, VU and RMS meters are different!” I know. They are related if you know how to interpret the measurements. I have conducted several tests on this. The outcome depends on the audio source (e.g. Sine Wave, Pink Noise, Guitar, etc.), but the RMS measurement consistently showed around 2-4 dB less than what the VU Meter was indicating.

Both of these meter types register signal more closely to how humans hear audio. VU Meter is more sensative to Peaks than an RMS

dBFS and dBu

A dBFS meter measures audio differently than the other methods I’ve mentioned. We know that +4 dBu is Line Level. The purpose of a dBFS meter is to show how much headroom you have in Peak Value before the audio clips, which occurs at 0dBFS.

There is no universal standard for the maximum dBu level. In North America, the maximum is +24 dBU, while in other parts of the world it ranges from +18 to +24. So if we use simple math, 24 – 4 = 20. This means there should be approximately 20 decibels of headroom when you reach Line Level.⁵

Now, let’s transition into the Digital world. If the maximum level is 0dBFS and we have around 20 decibels of headroom in dBu, then we could estimate that -20dBFS is approximately +4dBu.

What Audio Levels Should You Aim For?

So we are trying to get audio to come in at Line Level which is +4 dBu, which measures 0 on a VU Meter, which is approximately -20dBFS, which shows around -22 to -23dB RMS. This is the audio level you are shooting for.

6 Steps for Proper Gain Structure

1. There is a Correct Way for Gain Structure

In my opinion, establishing the right gain structure is crucial. Following a musical performance, maintaining appropriate gain levels becomes critical in gain staging and achieving a high-quality mix. Low audio signal can result in introducing too much background noise (noise floor), while excessive gain introduces “low-resolution” mixing, even though the term isn’t technically accurate—it touches on another subject entirely. Properly managing gain from the start ensures downstream processing adjustments are minimal, as consistent input levels reducing the amount of effort needed to get consistently great mixes.

2. Aim for Line Level

When we are setting audio levels, our target should be Line Level. Why should we care about Line Level if we are in the digital world? It’s true that Line Level is traditionally associated with analog systems, however it remains the benchmark we should target. Every piece of gear is calibrated and is optimized for Line Level signal. Not only will aiming for Line Level make sure your equipment is functioning at its best, you will build consistency in your mixes, no matter the platform, whether you are on your own or you have a team of volunteers.

3. Each Instrument is Different

Previously, I mentioned we should be targeting -20 dBFS or -22 to -23 RMS. What I have seen online, this is where I see 99% of the people get this part wrong. They will suggest that peak levels should be -18 dB. However, there is a small amount of people that say to shoot for an average of -18 dB. While neither approach is entirely precise, I lean towards advocating for the average method. Each instrument response very differently than the next. Drums and Guitars are very different. Percussion instruments typically produce higher peak levels to maintain the same average volume as a guitar.

I’ve meticulously analyzed each instrument’s peak levels in dBFS to align closely Line Level. There is nothing else like this anywhere else, and it’s yours for free. Just sign up for the email list and the Gain Structure Guide is yours.

4. You are working in a Digital audio Workstation (DAW)

It doesn’t matter what DAW you work on. The application is the same. You should have a RMS meter that comes with your DAW. Your target is between -20dB to -23dB RMS

If you have or want to download a VU Meter, Calibrate your plugin to register 0 VU at -20dB. The default setting is -18dB, but changing the settings to -20 dB will give you extra headroom. This may take some adjustment if you are used to mixing loud, but your mixes will be better and more consistent.

5. Gain Structure on a Digital Console

Most Digital Consoles measures audio in dBFS. I am going to assume you do not have access to a VU or a RMS meter. So how do you know if audio is at Line Level. One advise you probably get is “don’t clip”, but that is not helpful since there are many factors you need to consider if you are mixing in a live environment for Front of House or Back of House. I will be producing more content about these factors. Metering audio is not as a simple as one size fits all. Sign up to the email list and the free Gain Structure Guide will have measurements to use with a console.

There are digital consoles that have Analog metering. This is different than dBFS although the principles still apply. Percussive instruments need to be between 5-10 dB’s above 0 dB where as other instruments need to be between 0-3 dB’s over 0. Remember these are Peak Levels, not average levels. I stress that point because you may have very dynamic vocalists and their peak level may be very high compared to their average level.

6. Gain Structure on an Analog Console

Almost all Analog consoles have metering that shows negative numbers ascending to +10dB. There is a 0dB mark that you are aiming for. However, this is not a VU meter but a peak meter. It reacts differently than a dBFS Meter but it’s still measuring peak levels. Signup for my mailing list to get the free guide to hit the correct audio levels every time.

Now you know the truth about how important audio levels and gain staging is to your mix. If you can internalize the levels in the Gain Structure Guide, you can go into any situation and get a great mix whether you know the console or not. I have been in many new environments where I had to test my theories and everything I have mentioned in this post has been proven true. I challenge you to set a standard in mixing and gain structure. You will be a better mixing engineer whether you are live or in the studio.