Gain staging is paying attention to your levels at every stage of the tracking and mixing process. Or, from Wikipedia: “Gain staging is the process of managing the relative levels in a series of gain stages to prevent introduction of noise and distortion.”
Paying attention to your gain structure will result in better dynamics and a balanced signal to noise ratio.
Let’s first look at tracking considerations, then look at gain staging in the mix.
Impedance
Without getting too technical, pay attention to impedance outputs and inputs. In most cases, microphones and mixers are low impedance; instruments and amplifiers are high impedance.
A good interface will have a Hi-Z or instrument input. If your interface only has balanced XLR inputs, consider using a direct box between your instrument/amp and interface input.
If you plan on processing your microphone through an amp or an effect pedal, you can use a transformer to convert from low-impedance to high-impedance. A balanced XLR input with an unbalanced ¼” jack output is an example of this transformer.
Mic Placement
Pay attention to your mic placement. Adjusting your mic to your source sound is a first gain stage step.
Research mic techniques used on a variety of instruments and vocalists. It all depends on your project and goals.
A good vocalist can make a mixer’s job of handling dynamics easier by working the mic closer on quiet passages, or modulating, or backing off during loud passages, etc. Brass players can do the same. More obviously, a guitar cabinet is static, and it probably doesn’t make sense to have an assistant adjusting mic placement during a take that contains a wide range of dynamics.
If you’re recording in a room with a buzzing fridge, unplug that buzz before you record. Or else, get your mic as far away from the fridge as possible and as close to your sound source. The further away your mic is from your source, the more ambience will be picked up with it. If you’re tracking in a nice church or studio, maybe picking up that room ambience is desirable; but if you’re tracking in the basement next to a buzzing fridge, or droning air-conditioner, or obnoxious oscillating fan...
Mic Placement as EQ
Mic placement has EQ implications.
A mic placed directly up to the mouth of a male with a low register is going to result in audio with proximity effect, a boost in the lows.
Experiment with your mic placement and listen back to hear how your mic is responding to your source. Experienced engineers talk about solving EQ issues with mic placement. Your mic placement choices will make your job mixing either easier or more difficult.
Not Too Hot
In tape and analog recording, it’s important to keep distracting hiss and hum to low levels so that the signal is clearly in focus without the distraction of a loud noise floor.
When recording digitally, you don't need to push a channel into the red for a good signal level. Even the best converters, when pushed hard, may not sound as good as if you were to record at more conservative levels. You should have plenty of headroom between your peaks and 0dB. Don't over-think it. Just allow yourself some headroom, because when all the channels in your session are summed, and plugins are added, you're gonna need it.
In ProTools, aim for recording just below the yellow line, around -18db to -15db. The waveform isn't that big, but it's not a big deal. You don't need to hit the preamps any harder than this. Especially if you're a drummer.
-18dB is about where the top of the green line is in a PT mix. Having levels in this range prior to mixing is a good idea. It's just about looking for averages to work with. But If things sound good at -6dB, it's not important to get technical about it; you can always use clip gain or a trim plugin to attenuate.
Again, if you’re recording to tape, record as hot as possible without distortion so that your signal is well above the noise floor of tape and gear. If you’re recording digitally, you don't want to get close to digital clipping when capturing a source (unless you have some noise project or intentional effect you’re going for). In the digital realm, there’s no information to capture above 0dB.
Metering
Before you start your mix, make sure no tracks or busses are clipping. If you paid attention to levels during tracking there should be no worries here.
Use Pre-Fader metering while recording to ensure you're not recording too hot. Uncheck the Pre-Fader monitoring when you go to mix and add plugins.
LSR has a free VU meter. It’s preset is set to the standard -18dB reference.
Jacquire King has a tip for getting the kick and bass sitting nice together: using a VU meter, he gets his kick sitting at -3dB on a VU meter when soloed, and he gets his bass at -3dB in the same way (using -18dB as a reference on the meter). When the kick and bass are played back together, their levels sum to 0dB. If you’re dealing with drums and bass in your mix, this can be a good point of reference for your gain staging, and it can give you confidence that your kick and bass are sitting together sonically. After setting your bass and kick levels in this way, if the bass sounds too loud, there’s probably a monitoring issue you should investigate.
Trimming Inputs and Outputs
It’s common to have trim plugins before any other plugin on a channel. If there’s a channel or console plugin you’re fond of using at the top of your chain, there’s usually an input knob that can be adjusted for the same purpose.
For tracks recorded fairly hot, consider using a trim plugin to lower levels down to -10dB. If there’s a channel plugin you use, try it with no EQ or compression added, and just bring down the output of the plugin until you’re working with a level with more headroom.
Conversely, for quiet tracks, use a trim or channel plugin to raise a quiet track to -18dB or taste. +12db can be the max boost on plugins, so if you need more, just add a second trim plugin to boost. If you’re having to really boost your source audio in this way, you may just want to re-track, if you’re able to.
Remember, clip gain in Pro Tools is pre-insert as well as pre-fader, and can be used to attenuate or boost a track in the same way. Mixing with your eyes isn’t recommended, but with quiet tracks, it can help visually if you boost a clip/region with clip gain. If you have lots of clips/regions in a track, consolidating them can make for easier adjustments to an entire track.
Analog Emulations
You’ll find that a lot of plugins held in high regard emulate high-end analog gear, imparting pleasing color and harmonics to your signal. Keep in mind that these plugins often use a VU type meter and can have a sweet spots anywhere from -10dB to -20dB, depending on what gear the plugin is actually emulating.
Some producers like to hit favorite plugins hard because they like the way a plugin responds to a hot signal. Just be deliberate. If you hit these plugins too hard, your input signal will be overloaded and saturated from the start, affecting any plugins or processing down the chain.
When you load up a bunch of analog plugins on a channel, pay attention to their inputs and outputs. If your signal is too hot, or even too quiet, use a trim plugin to attenuate, or boost, the signal input.
It’s one thing if you’ve made a deliberate decision to overload an input for a desired distorted or clipped sound; but if it’s not intentional, introducing distortion into your signal affects every other plugin that comes after it, which can result in a loss of clarity.
The larger your session is, and the more plugins you use, the easier it is to get lazy and overlook overloaded plugins. So double-check and pay attention to every plugin’s input and output to preserve the integrity of your signal.
Manual Compression
Add gain and level rides before they hit the compressor. This will help your compressor’s workload.
If you use ProTools, try using clip gain and clip gain automation to make adjustments to levels before they hit the compressor. Again, clip gain is pre-insert. If you use clip gain for this type of manual compression, you can save your channel volume for your mix levels.
If you’ve created a comp of many different takes on one track, listen to how they play when assembled. Are some clips/regions quieter while others are blurting out? Instead of demanding your compressor to level the differences out, make your own gain adjustments before they hit the compressor. The compressor won’t have to work as hard to glue the separate takes together.
Use this type of manual compression to remove plosives or "ess's" in a vocal, improve a performance, and fix a track’s balance.
Magic Plugins
There are plugins like VocalRider that achieve a sort of level-riding, but riding a fader by hand or sculpting volume automation will most likely yield more convincing and musical results.
A plugin doesn’t know what’s best for your music--you do.
Then again, if a plugin like VocalRider helps you achieve what you’re after, use it. Just don’t use a plugin like this out of laziness. There’s no magic-mix plugin (plugin developers might sell you otherwise).
Summing Up
When all the channels in your mix are summed, try aiming for peaks hitting at -10db, but don’t freak out if they hit as high as -6dB. Remember, peaks can be attenuated easily in early mix stages.
Gain stage your plugins! When you bypass the plugin, unless you’re going for a different dynamic or effect, the input and output volume levels should be the same or similar.
When EQ is boosted, your judgement can get off, simply because the output is louder. Hear a one-to-one volume comparison so you can tell if you're making good EQ moves. And, if you’re boosting EQ, you’ll want to lower the output of the plugin to compensate for the boost; if you're cutting EQ, you'll want to raise the output to compensate for the cut.
If your mix is too quiet, turn up your headphones or speakers. Be careful with headphone levels and protect your ears!
Unless you’re going for Iggy Pop on the faders of “Search and Destroy," and maybe even then, being conservative with levels in a digital environment isn’t a bad thing.
Leave some headroom for mastering, if that’s the end goal.
Regardless of the genre and type of mix you’re trying to achieve, paying attention to and understanding your gain staging will only help in the process of getting it right.
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Thanks for reading.
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