How to set gain when recording your podcast.
I had a client send me a message recently. “We recorded 4 people with multiple microphones, and the gain must have been off because they're picking each other up."
And I thought firstly, "That's probably not what it was", and secondly, “People seem to be confused by this all the time, that’s a pretty darn good topic for a blog!”
So now here we are. Gain (in Vain)! What is it, how do you set it, why do you need it, how much protein powder should you… (not those type of gains). Now experienced audio folks probably need not apply for this one. But if you’re just getting started, or you need a refresher, read on.
What is Gain?
Gain, in the simplest terms possible, controls how loud the signal you record from your microphones (or other audio inputs) is. It's that simple.
You see, a microphone puts out only a teeny tiny amount of electrical current. It's not enough for a mixer, or an audio interface, or a recording device to use.
Instead, we need to run it through a pre-amplifier (more commonly called a ‘preamp’) to turn up that signal a little bit so that we can process or record it. By turning that preamp up and down, we can control the signal coming from our microphones to a sound level that works for recording. If you’re a photographer, you'll already know what I mean; a camera's ISO control is to light what gain is to audio.
Remember, this is different from the “volume” knob. "Volume" controls the loudness of the signal that you hear, not the one you record.
What's a 'good' gain level?
A good gain level is one where the sound is loud enough to get a nice strong signal. Not too loud, and not too soft. What's too soft? Well, let's do a little experiment, here. Turn your speakers or your headphones on if they’re off. If they’re on already, then hit pause on Spotify playing ABBA’s “Arrival” and listen. You hear anything? You shouldn’t.
Now I want you to crank that volume knob all the way up. (Be careful not to play anything otherwise you’ll blow your ears into your skull.) But do you hear that “hiss”? That’s what we call a “noise floor”. All audio gear has hiss, but the better ones have lower hiss (i.e. you have to turn it up more to hear it). You want your beautiful voice to be as loud as possible in relation to that hiss. That means we can turn the volume right down. We still hear your voice, but no hiss. You get me?
Excellent, so I just crank the gain all the way up, right? WRONG! You see, eventually the audio signal becomes TOO loud for your recorder or mixer to handle. You’ll hear it "breaking up", or “clipping”, or “peaking”, or “hitting the ceiling” or a gazillion other audio slang terms for the same thing.
If you want a VERY laboured analogy for this, think of trying to send a birthday cake to your friend. If you make the cake too big, the box will squish the writing so "HAPPY BIRTHDAY JANET" becomes "HBPIY BILATHY JNUT". Best to skip that third layer on the cake so it fits inside the box! That was terrible. Forget that, maybe just listen to this...
What level do I set my gain at?
Turn it up to eleven, right? No. Anyone who gives you a specific number to set your gain knob at clearly thinks you’re an idiot, and you shouldn’t be friends with them. Instead, you should spray them with a fire hose while yelling “YOU ARE INCORRECT! BE GONE, VILE AUDIO MISLEADER!”
It’s impossible to say “just set your gain knob to three” (which as any Simpsons fan knows, is medium-brown). Because there’s a crap-ton of variables that affect what your gain should be, including (but not limited to):
What type of microphone you’re using
How loud you are
Whether you’re recording to analogue or digital
What the room is like
If you use a pop filter
Whether or not you had breakfast, the phase of the moon, how long it’s been since you last watched an Adam Sandler movie... (maybe)
So you can see, it’s complicated. But not really. Turn that fire hose off and I'll teach you how to set that gain!
How do I set gain?
So see those VU meters on your recorder? Likely your recorder or recording software has one, either analogue with a bouncing needle, or digital with some LED lights or a "progress bar".
You may have seen it bouncing around and figured out that it goes higher when sounds are louder. As we heard earlier, it’s bad when this level is too low and it’s bad if this level is too high.
So here’s what you’re gonna do. You’re going to speak/play music/do your sound effect into the microphone. At the same time, adjust your gain knob so that the VU meter is peaking (on average), at a good level.
What's a good level, you say? Now some old-school folks will say you need to set gain as high as you can without clipping. This was true back in the old-school analogue tape days, for a whole bunch of complicated reasons I won’t get into here. But a couple of simple rules:
Some VU meters have a helpful little hash mark (#) or something to point a good level out to you. If that's the case, use that.
If your VU meter's top value (i.e. the highest number at the end of the scale) is zero, (like it is on most digital meters) then you should be aiming for around minus 12. You'll notice the hash mark (above) usually sits around here for most gear.
If you're recording with an older meter where the numbers go PAST zero (from -2, -1, to 0, +1, +2 etc) then you should aim to peak at around zero.
If you’re recording into something with no VU meter, (like my Focusrite 2i2) then you likely have one or more "idiot lights" to show your signal. I go by the “green light good, red light bad” mantra. If you’re getting green lights, it’s a nice strong signal. Red lights mean you’re approaching clipping.
Now none of this needs to be super accurate. Just set it to around the right level and forget it. If you go over, these levels will give you enough “headroom” so that loud sounds won’t clip, but enough signal so that you’re well above that noise floor. Setting gain is literally that simple.
So what if I am picking up unwanted sound in my recording. Is that a gain problem?
No it's not. If you have to turn the gain on your microphones up so much that you start hearing other people, then it’s time to start looking a few other things:
Make sure you get that microphone up close to your face. For most microphones around the width of your hand is a good starting point. This means you’ll get nice loud signal from the person talking in relation to the background noise.
Make sure that microphone is facing towards the person you want to pick up, away from the people you don’t. Microphones that say they have a “cardioid” (heart-shaped) pickup pattern are less sensitive from the back. So if you and your co-host are facing each other with the mics back-to-back, that’s the best solution.
Look at echos in your room. Even microphones pointing away from each other aren’t gonna reject sound that’s bouncing all over the place. Carpeting helps, soft furnishings help, well-placed couch cushions… all help!
Good headphones! Sometimes if you and your co-host use headphones, sound from yourself and your co-host can “bleed” out the headphones and get into your microphone, causing echos and crossover. Make sure your headphones fit you well, are “closed-back” type, and aren’t turned up too loud.
But remember, kids, unless you're recording in individual soundproofed booths, it's likely that you'll get at least some bleed of multiple people in each channel. Best just to try and minimise it and work with it as best you can!
Play it a-gain, Sam!
Gain is a really super simple concept that some people get really hung up on. People think not setting the gain to some mysterious “correct” setting is wrong. But using your VU meter will get that gain setting as correct as it can be, and from there you need to start looking at other places if you're still getting audio problems. Gain is a really super simple concept that some people get really hung up on. But as you can see, most of the problems that people think are caused by not setting the gain to some mysterious “correct” setting are actually caused by something else.