Gain Staging 101

Gain Staging: it may not be the most glamorous or the most thought of aspect to getting great sound, but it’s absolutely one of the most important. First, what is gain staging? Really, gain staging is just a fancy way to say “Where is the level of my signal being boosted or cut during my signal chain?” Lets follow our signal on a journey from it’s source (a microphone or line input) to it’s end (the speakers) and see where we might be adding gain and how to add it correctly.

First, a microphone converts an acoustic vibration in to an electrical signal, which then travels down the mic cable until it gets to your mixing board. The issue with this signal is that it’s usually very weak and we’re going to need to amplify it before the mixing board can really process it effectively. Knowing that, it makes sense that the first gain stage that the signal hits is the Microphone Preamplifier or mic pre. This is usually controlled by the knob on the top of the board that says “Gain”. By turning up the gain knob, we’re amplifying the signal from the mic as it comes in to the mixing board. It’s absolutely crucial to get this first gain stage right, because it effects all the later ones. What we want to aim for on a traditional analog board is to turn up our preamp gain until our signal peaks around 0 dB on our meter. On some boards, you might be lucky enough to have individual meters on each channel, or you may have a PFL button (which stands for Pre Fader Listen) which, when you press it, will show the level of just that channel on the master meter instead of the level of the whole mix. The reason we want our signal to peak around 0 dB is because a mixing board is calibrated to perform at its best when a certain level of signal is present, and typically that level right at 0 dB. When the signal is coming through with the correct amount of gain applied to it, your eq will sound better, any inserts will be receiving the optimal amount of signal, and you won’t have to try to add gain later with your fader.

So now we’ve got our preamp gain set…so what’s next? Usually either an EQ or a compressor, or your board may have an insert point where you could patch in a variety of outboard effects like a gate or an outboard effects processor. At this point, what we’re really trying to do is just to maintain the level that we achieved with the preamp (aka peaking around 0 dB) so what we have to do is to make sure that anything we add doesn’t increase or decrease the level too much. For example, if you have an EQ next in your chain, you want to make sure that you have enough headroom (headroom is the amount of signal that your board can handle before distortion occurs) that you can do your EQ boosts and cuts and not distort your signal. Typically the EQ on your board will provide plenty of headroom for you to make necessary EQ boosts without distorting the signal, but it’s important to listen when you’re EQing to make sure nothing bad is happening. So if you start with a nice clean sounding kick drum, but then you crank the bass 20 dB and it sounds like a fart…you may have used up all your headroom. For this reason, I prefer to use “subtractive EQ” whenever I can. Subtractive EQ means that I cut frequencies instead of boosting them. So if my vocal sounds muddy, I would first reach for my low and low-mid eq knobs and turn those DOWN rather than trying to boost my high eq. To my ear, this sounds a lot better, and I guarantee you won’t run out of headroom.

Next, let’s say your board has a compressor, or maybe you’re on a fancy digital board and you have a compressor plugin. The important thing to remember here is to equalize your level as it goes in and out of the compressor. So if your compressor is reducing the signal by 6 dB, make sure that your make-up gain is compensating for that loss in signal. Remember what we talked about in my Compression 101 article: the job of a compressor is to turn down the loud parts of a signal. So after that happens, we need to turn it back up to compensate. Always look at the input and output levels on your compressor to make sure there’s not too much of a difference between what’s going in and what’s coming out. A lot of times when people insert a compressor and think that it sounds good, really all they’re hearing is an increase in level, and our ear goes “louder is better!” and we think it’s good, but keep in mind that your goal in compression is NOT that the signal gets louder, but that it gets more full, punchy, and controlled.

So hopefully, now that our signal has passed through several gain stages, and you’ve staged them well, the level of our signal is still peaking right around 0 dB, so it’s time for the last stage before our individual channels get mixed together: the fader. The way I see it, the fader is there to mix with. Wait…that sounds way too simple right?? Actually no, that’s really all it does…assuming that you’ve had correct gain staging up to that point. So let’s talk first about what a fader does NOT do: it’s not there to provide a long term boost to your signal. If you’re constantly pushing your lead vocal to +12 dB with your fader to get it loud enough, chances are you’ve got something wrong earlier in your signal chain, OR your other instruments are too loud. Mixing is a continual balancing act. If you push your guitars really loud, suddenly you lose your lead vocal, so you turn that up…then your drums and bass get lost. It’s can become a vicious cycle of turning things up until eventually…you run out of up! The issue of running out of “up” can be solved like this: try to keep your faders at the 0 dB mark or below. If your vocal isn’t loud enough, turn other things down to build your mix, rather than trying to turn the vocal up. Sure, there may be moments during a song where things just get especially loud and you need to push the vocal past 0 dB so that it can be heard. That’s totally fine, it’s just something that happens with a live band. But if you consistently push levels past 0 dB, chances are your mix would be improved by turning other elements down instead.

Ok now what? We’ve set our input gain on the preamp, we’ve made sure to try to cut rather than boost our eq, our compressors and other effects have a consistent level coming in and out, and we’ve set our faders so they don’t really go over 0 dB which means we have plenty of headroom. Now our mixing board does what it’s name suggests: it mixes everything together. This can be one of the most frustrating gain stages if you’re not careful. The mix buss is additive, which means that the more you put in, the more you get out. So if you put in a bunch of loud signals, you’ll get an even louder signal coming out. This is yet another reason not to keep boosting things with your faders. Remember that optimal level of 0 dB? If you have a bunch of things pushed above that with your faders, you’ll run out of headroom on your master buss REALLY quickly and you’ll have distortion. In a perfect world, we would end up setting our master fader to 0, and the master meter would also display an output level of 0 dB, but this is the real world and that doesn’t always happen, so you may need to move your master fader a little bit to get it there. Also, we work in the church world with old people who complain about loudness, so we might have to use that master fader to bring the overall level down some to keep everyone happy.

Last but not least, our signal leaves the mixing board and goes out to the power amps before the speakers. Hopefully, we’ve got a mix with great gain staging and all the power amps have to do is increase the level of our signal loud enough to power our speakers, but once again we want to make sure that the level isn’t too high or low going in. Most power amps have an input and output gain with lights to tell when it’s receiving an appropriate level of signal. If it says it’s clipping, turn it down! If it says it’s not getting enough signal, turn it up! Then go back out in the room and listen to your epic (and perfectly gain-staged) mix!

Until next time, #CrankThatBass