Gain Staging: Understanding It’s Importance

3 VU meters used for gain staging

In the professional audio world, the term gain staging is incredibly common and a generally well-recognised concept. However, within the world of home studios and bedroom producers/musicians, it’s a concept that goes missed far too often. This is one of those really fundamental topics that everyone needs to get a handle on if they want to succeed in the recording/production world. Just like learning basic mixing is essential, understanding the importance of gain staging is equally paramount. This article dives into the concept of gain staging, how to keep a good handle on it, and where it applies in both the digital and analogue worlds.

So What Is Gain Staging?

Put simply, gain staging is taking control of the level between every process of your signal chain and adjusting it to prevent unwanted problems. When I say problems, I am referring to clipping (too loud) or noise floor (too quiet). If you’ve ever wondered why certain plugins or pieces of hardware have an output level control, you’ve just found your answer.

I know that to some of you that sound like a strange thing to wonder. However, the question “Why does it have an output volume control when I can just turn down the fader?”  comes up far too often. Let me take a second here to break it down for any of you that might be thinking along those lines.

The output control on an Empirical Labs Distressor

Gain Staging in the Analogue Realm

Between every plugin or piece of equipment, we have to have control over the transferring signal. For an analogue example, let’s think about a microphone going into a preamp. In this chain, our two processes are the microphone and the converters in our preamp. In order to control the level moving from our microphone to our converters, we have a gain knob. This allows us to implement gain staging by setting the level at which the sound moves between the two processes.

Why is this helpful? Well, not to mention the obvious point of being able to hear what’s happening, it allows us to control those problems we talked about earlier on. If we have no control over the gain, our microphone hits the converter too hot and we end up with potentially nasty distortion ruining our recordings. Inversely, if we hit the converters too soft there is likely to be electrical noise imparted on our signal. This means that when we turn it up in the mix to an acceptable level, it’ll sound fuzzy and generally unpleasant. You see now the importance of setting correct recording levels and having control!

So How About Digital Gain Staging?

Well, the sample principles apply when mixing in the box. Let us say your mixing that vocal you just recorded with perfect analogue gain staging. First up you decide to chuck in an EQ plugin to make a few boosts here and there. In doing so, you’ve increased the output level of the EQ process and potentially clipped your channel. If you were to immediately throw in a compressor afterwards to apply some gain reduction, you will probably see that the signal no longer passes 0dB and so all is well right?

An example of digital clipping over time

Not so simple I’m afraid. The signal that is passing from that EQ has already clipped. This means the signal itself is now permanently distorted. If you don’t turn down the output of the EQ plugin before the signal flows to the compressor, you won’t remove that clipping. Starting to see the importance of that output volume control now right? Equally, (although less common), noise floors can have the same effect. Typical digital applications have such little noise in them that it’s never an issue but let’s say you’re using an emulation of an older piece of hardware. The original noise flaws that this unit had will likely be combined into its digital counterpart. If you’re working too quietly in one of these plugins and then you use a second plugin to turn back up, all that noise is going to come up with it. Your music is going to start sounding like a broken TV pretty quickly.

Moving on to Mix Downs

I’m sure by now you’re starting to understand the important part that gain staging plays in the audio world. Another quick example that I want to cover is mixing down. This is especially important when it comes to preparing for mastering. You’re nearing the end of a mix session and everything is sounding really great. Beautifully clear high end and strong, punchy lows. However, your master fader is peaking around +2dB and distorting the track in places. No worries, just turn the master fader down 5/6dB and we’re all good right?

WRONG!

In a similar fashion to what we discussed earlier, if your processes (in this example, your processes are each individual channel) are flowing into the master and causing it to peak then simply turning down or compressing the signal only hides the issue and does not solve it. To rectify this problem, you need to turn every signal channel that feeds to the master down by 5/6dB. This brings the master down, eliminates clipping and creates plenty of headroom for that all-important mastering stage. Also, for any of you thinking a limiter will solve this problem, it will not! The same principle applies. If it’s already clipped before hitting the limiter, then it’s permanently clipped.

If you’re DAW is working at a 32-bit floating point, you can in fact just turn down the master fader to avoid clipping. With a floating point bitrate, the 0dB point can move around dependant on the signal in order to avoid clipping. Working this way means that we don’t have to adjust the level of each fader in a mix. Just remember that this only applies to the signal flowing inside the DAW. You will still need to turn down the master fader before bouncing. It’s always best to practise good gain staging when mixing, regardless of bit-depth.

Good gain staging with headroom before mastering

What Exactly to Aim For

I’m going to go out on a limb here and say that a large percentage of you reading this are working In The Box and don’t use much analogue outboard equipment. As such, I’m going to focus on metering levels and appropriate gain staging in the digital realm. Most of this can be applied in the analogue world as well. To be perfectly honest if you’re working analogue, you probably understand most of this already.

In order to ensure you’re in a good place in terms of headroom and that you haven’t got too much signal flowing between each process, you’ll need a good way to read it. All DAWs have got digital faders these days and they can be great for keeping an eye on things. However, your faders are always at the end of the signal channel in a channel so they are only ever showing the level of your signal after every process. This isn’t much help for knowing whether you’re too loud or too quiet between plugins. In order to keep an eye on this, I recommend using some form of VU Meter.

For those of you not familiar with the concept of VU, they are the original ammeter style of tracking loudness using the VU (Volume Unit) measurement signal. This style of metering has a ballistic design that operates on voltage as opposed to signal level. If you don’t have a plugin like this, I recommend checking out StereoChannel by Sleepy Time DSP. This handy free plugin is easy to use and has an adjustable nominal level. This means that if you suspect clipping somewhere in the chain, you can squeeze it in between two other processes and have a look at what’s going on.

A stereo VU Meter

Nominal Level?

When I say adjustable nominal level, I am talking about the number of decibels that 0VU is equal to. VU meters can be calibrated to provide any metering system you like. The most commonly recognised and used nominal level for the last 60 or so years is 0VU = -18dBFS. This means that if your VU meter is reading 0VU, your signal is at -18dBFS. Equally, if your VU meter reads at +6VU, you know your signal is -12dBFS as 1VU is equal to 1dB. Making use of this scale and utilising the standard settings means you can ensure perfect gain staging between each process without any serious problems. Happy days!

On a side note, an adjustable VU meter is a very handy tool for any of you who are sending your tracks off to be mastered. If you set your nominal level to -6dBFS, then you know that 0VU = -6dBFS. By doing this and chucking it on your master fader, you can make sure the loudest part of your mix peaks at -6dB with accuracy. As long as the needle doesn’t pass that 0VU mark, you’re all good to go!

TL;DR

Whether you’re working in the analogue or digital world, gain staging is incredibly important to ensure correct signal levels. Too much signal is going to cause clipping and distortion which can completely ruin your productions. Too little signal and you risk introducing a lot of noise into your tracks. You just won’t be able to get rid of that. Follow the tips in this article to ensure a consistent balance between each process you make.

Remember that gain staging is also key in routing. If when your tracks combine on your master channel they cause clipping, you must turn down the channels and not the master channel. Prevent clipping before it occurs and not afterwards. If you’re struggling to get a good idea of your gain staging and discover clipping issues in your signal chain, try using a free VU meter plugin. You can slot this in between any two steps in your chain to see what level the signal is outputting. This guarantees no clipping and perfect gain staging!

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