Gain staging is one of those magical terms that pop up everywhere in audio engineering. If something sounds noisy or distorted, the first thing someone will say is, “Oh, you must have gotten your gain staging wrong.”
Sometimes – maybe even often – they’re right, but it would help if you knew what gain staging even was, since that would help you fix it. Here’s a quick primer.
What's the purpose of gain staging in mixing and recording?
For each link in the audio chain, whether it’s a microphone or a preamp or a mixer channel or an audio interface or a plug-in, there is a sweet spot.
In this sweet spot, the signal is as strong as it can be in relation to the noise that the link creates.
The aim of proper gain staging is to maximize the signal-to-noise ratio (S/N) of each piece of our audio rig. Because then the signal gets passed along with the most possible good stuff and the least possible bad stuff. Remember, whatever bad stuff is there will only make things worse further down the chain!
What's a signal chain?
We refer to the path audio takes from the microphone to the recording medium as the signal chain. That’s not a bad analogy; we can think of each piece of gear as a link in the chain. But jumping to the old adage “A chain is only as strong as its weakest link” doesn’t really get us anywhere.
In a signal chain, it’s not just about ‘strong’ or ‘weak’ links; it’s about each link doing its best at what it was designed to do, so that the links that follow it benefit most from how it does its part.
The most important thing about gain staging
When we talk about distortion in a discussion like this, we’re not necessarily talking about fuzz, overdrive, or tube amp saturation.
We could be talking about anything that changes the audio in ways we didn’t intend, like a compressor that’s set to ruin a track’s dynamics or an EQ that’s bringing out a mic’s screechy highs – “distortion” as in “something’s twisted my audio out of shape and I don’t like it.” Okay?
Here’s the most important concept of the gain staging procedure: distortion is cumulative.
What that means is that if something early in the audio chain introduces distortion, that distortion will travel all the way through the signal chain along with the desired signal.
As it goes from link to link, it will encounter other forms of distortion, which will further distort the distortion, which will in turn be distorted even more at the next link in the chain, and so on, like a small snowball rolling downhill that turns into an avalanche.
In other words, 1 + 1 + 1 = 3 in math class, but in audio, 1 + 1 + 1 can equal 4, or 5, or 10, or 100…
For each link in the audio chain, whether it’s a microphone or a preamp or a mixer channel or an audio interface or a plug-in, there is a sweet spot. In this sweet spot, the signal is as strong as it can be in relation to the noise that the link creates.
You want to maximize the signal-to-noise ratio (S/N) of each piece of our audio rig.
This way, the signal gets passed along with the most possible good stuff and the least possible bad stuff. Remember, whatever bad stuff is there will only make things worse further down the chain!
4 easy steps to Gain Staging
Gain staging can involve some back-and-forth experimentation to get things as good as they can possibly be, but the basics are easy to apply.
1. Be methodical.
It’s tempting to jump all over the place to see if this or that does any good, but if you do that, you’ll never be really sure of what you’re fixing or making worse, and if things do get better, you’ll have no idea of how you did it.
2. Start at the beginning of the chain and work your way down.
If you’ve placed your FET condenser mic too close to the amp cabinet and it’s clipping, don’t try to fix your plug-ins! Pull the mic back or put a pad on it. Then move to your preamp and adjust it so the signal is loud but clean; most pres will suddenly add a lot of hiss at the top end of their range, so only push them so far and no more. And so on.
Here’s an easy test for you to try. Put a mic up on a source, then play with getting the best level with the least noise at the output of your mixer – but the only things you’re allowed to change are the preamp gain and the channel fader. What you’ll discover is that there’s a particular balance of gain and level that gives the cleanest signal at the desired volume. Usually you’ll want to get the most possible gain from the pre rather than pushing the fader all the way up.
3. There’s overload and then there’s overload.
Some signals are supposed to be overloaded, ever so slightly or all the way up. A tube microphone that’s hit hard produces even harmonics that sound good to our ears, so that’s a good thing. On the other hand, a signal hitting an audio interface too hard will be heavily clipped, and that’s a very not-good thing.
4. Getting clear audio into your DAW isn’t the finish line.
So you’ve got the very best S/N you can through your audio interface’s A/D converters and now it’s safe and sound in your software. We’re done here, right? Wrong.
Because we tend to see computers as ‘black boxes’ whose inner workings we don’t understand, we can assume that once audio’s in the box, everything’s going to be fine.
In fact, running digital audio through a DAW – mixing it, EQing it, adding effects – is just as prone to gain staging problems as what happened in the outside world… and digital distortion, where a signal is pushed above 0 dBFS and just clips, is anything but pretty. You have to be just as systematic and just as vigilant as you finalize your mix in your DAW.
5. Go back and check your work.
If there’s something that still sounds off, go back through the chain and test each link – gently, and one step at a time. Random messing around will undo all of your good work and leave you back where you started, or worse.
The principles of gain staging apply to other parts of audio production
You can probably see that these principles apply to many other parts of audio production: effective EQ, setting up a compressor or limiter for the sound you want, adding effects, and so on.
But in most cases, your audio will benefit most from getting your gain staging right – and it should always be where you start, because if your gain staging is off, nothing you try will fix things.
So now you know what gain staging is and how to deal with it. The last step is also the first: practice, practice, practice.
Every gain staging problem will be slightly different, and only building up skill will give you the confidence to re-attack the problem every time. But the more you practice, the more quickly you’ll get where you need to be.
Have fun, and remember: if the flashing red Peak LED is on something digital, you’re not giving it a little mojo, you’re using a chainsaw. Stop it.