The First Leg Of The Stool: Volume
Mixing Music: Controlling Levels
If you haven’t read the intro post in this series called Mixing Is A Three Legged Stool or the first post on how to listen like a mix engineer, you may want to start there. Otherwise, let’s get started.
Let’s take a look at the first leg of the stool, which is volume. For the purposes of mixing, I’m going to define volume as “the loudness of a track or specific frequencies in it relative to the other tracks in a mix.” At this stage of the game, we don’t care how many LUFS it is or anything like that. For mixing, you usually only care if you want the vocal or the synth, for instance, to sound more prominent, and thus, higher volume. It’s worth noting that volume is absolutely the most powerful tool you can use when mixing.
Volume or loudness in audio is cumulative. When you play two tracks at the same time, their volume sums and so both together are louder than either. That’s obvious enough and probably goes without saying, but, it’s important for building a conception of what you’re trying to do when mixing for volume.
Mixing is basically about fitting sounds into a three-dimensional game board:
Amplitude: how loud a sound is, typically depicted on your spectrum analyzer’s y-axis
Frequency: how high or low a sound is, typically depicted on your spectrum analyzer’s x-axis
Time: when a sound happens, shown on your DAWs timeline
In the intro post for this series, I said that many problems people try to fix in mixing aren’t mix problems at all: they’re production or arrangement problems. Many of these problems fall into the time dimension. For instance, if a kick drum and a bass synth don’t ever play at the same time, then you don’t need to mix them at all. If you mix enough songs, you’ll see this a lot: two singers singing at the same time, guitar and synth battling it out for space, and so on.
Remembering to avoid unnecessary battles in mixing your own music is an important step in the process of making great mixes, and it often ultimately serves the song better, by giving the listener a clearer idea of what you really want them to pay attention to. This is where a lot of beginners get turned around, but it happens to pros too. Stay focused and you’ll be golden.
When you are starting your mix and trying to balance the volume of all the parts, your goal is to fit all the sounds within the available amplitude (-∞ to 0 dB, after which the sound will clip) and available frequencies (generally about 20 Hz to 20 kHz, for human listeners) over time.
Concepts And Tools For Controlling Volume In A Mix
There are many tools available for mixing, but in reality, most of them are a distraction. While there are many great people and companies making plugins and hardware, you are likely not missing out on much by keeping your workflow simple and focused, especially if you’re just starting out or feeling like you’ve hit a wall in your progression. When the vocal gets swallowed by the guitars, you’re not dealing with a compressor problem. You’re dealing with a volume and frequency balance problem.
The Recorded Audio and Gain
You recorded some audio, and you recorded it at some level. A good guideline for initial recording and gain staging is to record where the peak levels are hitting about -6 dB and most of the audio is hovering around -12 dB. You can adjust clip gain in your DAW to change the pre-fader levels of this audio file. This adjustment essentially makes the waveform you recorded bigger or smaller. This is the first part of every track in a mix, and it’s always worth investing the time to make sure you’re happy with the base recordings you’re making.
Gates/Expanders
Gates are tools that only allow sounds over a certain threshold to pass through. A common use for these would be on drums or cymbals that have a long decay. You may only want the loudest, most impactful part of a long cymbal hit to play. A gate will automatically shut off the cymbal sound once it reaches the threshold. Gates operate abruptly. Expanders can be smoother and do the same thing. You can operate an expander in an upward or downward fashion. Upward expansion (which isn’t terrifically common in mixing) increases the difference between loud and soft sounds above the threshold, and downward expansion turns down sounds quieter than the threshold. An expander is essentially the inverse of a compressor.
Equalizers
An equalizer, or EQ, allows you to boost or cut the volume of specific frequencies, and many have high or low pass filters that allow you to eliminate all the sounds above or below a cutoff point. Use an EQ to remove volume from frequencies you don’t want to feature (or filter them out entirely) or to add emphasis to certain parts of a sound. Generally speaking, it’s often best to do corrective (subtractive) EQ before you compress, so that you don’t wind up making the sounds you don’t want louder before you remove them.
Compressors
Compressors are essentially an automatic volume knob. They typically have four main controls: threshold, ratio, attack, and release.
The threshold is the volume at which the compressor says, “this is too loud!” and begins turning down the volume. So, if you set the threshold to -12 dB, a compressor will completely ignore any sounds quieter than -12 dB (relative to input level), and will only act on sounds that meet or exceed -12 dB.
The ratio of the compressor determines how aggressively the compressor works to keep the volume under the threshold. At a 10:1 ratio, anything 10 dB over the threshold gets reduced so it only ends up 1 dB over. At a 3:1 ratio, 3 dB over becomes 1 dB over.
The attack on a compressor is the setting for how quickly the compressor reacts to sounds that exceed the threshold you’ve set. A short attack clamps down on transients while a longer one does not.
The release on a compressor is the setting for how quickly the compressor turns the volume back up after the sound has stopped exceeding the threshold. A short release will let the volume spring back quickly but a longer one will not.
Many compressors also have a setting called knee, which is really commonly misunderstood by people when they’re learning how to use compression. The knee is just how quickly or slowly the compressor’s ratio ramps up in response to sounds that cross its threshold. A hard knee operates the compressor immediately and at the full value of the compression ratio you set, whereas a soft knee is smoother and ramps up the ratio over a short period of time. A softer knee is great when you want more transparent compression and a hard knee is useful for when you want more control.
One of the easiest ways to learn how a compressor works is to make a repeating MIDI pattern of repeated quarter or half notes, played on a basic sound, like a saw wave. Play the note over and over and adjust the compressor’s settings until you get a feel for how your compressor works and sounds. To start, set a very high ratio with a medium attack and decay time so you can really hear the compressor working.
A limiter is just a compressor with an infinite ratio, so it never lets any sound exceed the threshold. A multiband compressor is essentially a series of compressors that work together with phase-coherent crossovers, to let you compress different frequency bands of the same sound differently.
Many compressors also have what’s called makeup gain, which is applied after compression. Because compression makes sounds quieter, makeup gain allows you to bring back some of the volume you’ve lost (or add more).
Clippers
Essentially, clippers chop off the loudest parts of sounds. There are hard clippers (which make aggressive, square cuts) and soft clippers (which make smoother, rounded cuts). Clippers are typically used to eliminate the extremities of transients in a mix. If you load up a clipper onto a snare drum track, for instance, you will often find that you can remove many decibels from the transient attack of the snare drum without audibly changing its sound. While clipping can be used to create distortion effects, in mixing, it’s more often used to eliminate extraneous sonic information that provides little to no value to the listener, because oftentimes, transients peaks contain 3 to 6 dB (or more!) of sound that has very little energy or duration.
Transient Shapers
Transient shapers operate similarly to compressors, but the user doesn’t set a universal threshold. They detect transient spikes algorithmically and are level-dependent per transient. Transient shapers are best used to shape the character of a sound, for instance, when you have a drum sound with a sharp transient attack and another sound that plays at the same time, like a bass. Using a transient shaper on the bass can put a little space between the transient of the drum and the bass without changing their timing, which will allow both to be heard more clearly.
Saturators
Saturators are typically about changing timbre, but some can help with loudness when used subtly. One saturator that’s notably useful for mixing is the Sonnox Oxford Inflator. The Inflator is a nonlinear waveshaper that increases perceived loudness by adding controlled harmonic density—essentially a psychoacoustic saturator. Other tools like the Black Box HG2 can also boost perceived loudness, but you have to be careful not to change your sound when using them. When not pushed hard enough to add grit to sounds, saturation increases perceived volume by adding harmonic density to sounds. Saturators are most effective when you don’t want to sacrifice headroom in a mix but you want a certain sound to come forward in the mix. Additionally, saturators can be highly effective at boosting loudness when mastering.
The Channel Fader
The channel fader in your DAW acts like a voltage controlled amplifier, or VCA. It can make the waveform you’ve recorded louder or quieter without adjusting the gain of the recording. Generally speaking in a DAW, you want to be using this to reduce the volume of tracks.
Final Thoughts On Mixing And Track Levels
I know this is a lot to take in, but mastering control of levels is non-negotiable if you want your music to sound professional. If you can shape volume without damaging sound, you can mix confidently in just about any situation. I’ve met audio production school graduates who couldn’t succinctly and correctly explain the functions, uses, and differences between compressors, transient shapers, and clippers, so if you can really absorb and master these concepts and skills, you’ll be well on your way.
Get volume right and everything else becomes easier. Space and timbre are up next.
See you next time.
