Mixing music and audio is a technical skill that requires certain tools and processes to be done correctly. Professional mixers are called “engineers,” after all, and all engineering professions are governed by processes and defined tools (processors) for the job.
What are the essential processes and processors of mixing music/audio? Beyond the necessary tools of a mixer/workstation (hardware or software) and monitoring system (headphone or speakers), mixing engineers require gain staging, volume faders, pan pots, equalizers, compressor/limiters, distortion/saturation, time-based (delay/reverb) and modulation effects, and more.
In this article, we'll touch briefly on the necessary base components of a mixing rig. However, our main focus will be on the craft of mixing and the processes that make mixing possible.
I'll be prefacing our conversation with the bare necessities and basic philosophy of mixing. If you'd like to skip ahead directly to the essential processes, please do so by clicking this link.
The Bare Necessities Of A Mixing Engineer
There are a few base-level tools a mixing engineer needs to mix before we can even begin to talk about the essential processes.
First, a mixing engineer needs a mixer. This could be a physical mixer (analog or digital) like those seen in live venues or broadcast centres, or mobile setups.
Related article: The Ultimate Audio Mixer Buyer's Guide
More commonly, today, this means a DAW (digital audio workstation). We also need a computer with adequate specifications to run a DAW properly.
Related article: Top 7 Best Digital Audio Workstations (DAWs) On The Market
The mixer/workstation is the central component that allows mixing to take place, so it's completely essential.
Second, a mixing engineer needs to be able to monitor the mix. This is generally a pair of studio-quality headphones and/or a pair of studio monitors (or multiple pairs of each).
For help choosing the best headphones and studio monitors, check out the following My New Microphone articles:
• The Ultimate Headphone/Earphone Buyer's Guide
• The Ultimate Studio Monitor Buyer's Guide
In addition to the mixer/workstation and monitoring system, mixing engineers also require interfaces, cables and a working environment. These are beyond the scope of this article.
Mixing is also enhanced by acoustic treatment, studio furniture, external hard drives and more (also beyond the scope of this article).
For my take on the best acoustic treatment and hard drive brands, check out the following My New Microphone articles:
• Top 11 Best Acoustic Treatment Brands For Home & Pro Studios
• Top 11 Best External Hard Drive Brands For Music/Audio
Now that we've covered the basics, let's dive into the art of mixing and consider the essential processes that go into crafting a high-quality mix!
Visualizing The 3D Space Of Mixing
A great stereo audio/music mix is dimension. Just as we hear sound natural in 3D space, so too should a mix be in 3D space. This means there are the following three dimensions we should be concerned with in a mix:
With this dimensional framework, we can better comprehend the importance of the essential mixing processes.
The Depth Dimension Of Audio Mixes
The depth of a mix refers to the virtual separating of elements based on the perceived distance from the listener.
Depth is created mostly with volume differences and reverb times.
EQ in the high-end also has an effect on perceived distance/depth since high-frequency sound waves lose energy much faster than low-frequency sound waves. Therefore, cutting the high-end with EQ can push an element further back in the mix.
Compression also has an effect on depth due to its effect on transients. Fast-attack compression can attenuate transients, moving elements further away from the listener. Slow-attack compression can have the opposite effect, moving sources closer by accentuating the transient.
The Width Dimension Of Audio Mixes
The width of a stereo mix refers to the differences between the left and right channels and the perceived soundstage from left to right.
Width is created mostly with panning, especially with double-tracked/over-dubbed elements.
Any stereo effect can have an effect on the width of a mix, including many modulation effects and stereo delay.
The Height Dimension Of Audio Mixes
The height of a mix refers to the range of frequencies, from high to low, that are present in the mix. A tall mix will cover most of the audible range from 20 Hz to 20,000 Hz (sub-bass to air/brilliance), while a short mix will have a more limited frequency range.
While height is largely a matter of arrangement, EQ plays a major role in this dimension.
Let's now focus our attention on the essential tools in a mix and how they affect each of the dimensions mentioned previously. I'll add links to more in-depth information as we go along!
The essentials for the art of mixing (excluding the necessary base-level equipment) include:
- Faders/Volume Control
Let's touch on each of these processes.
Channel faders control the volume of individual tracks and are necessary for balancing the mix.
A proper balance between the elements is the more critical aspect of a good mix.
Therefore, faders/volume control is an essential process for mixing.
Panning effectively places individual tracks (or buses) at an angle within the stereo field. Panning is the most basic method of creating width in a mix and provides separation between elements.
Compression is a super-powerful process, capable of many different tasks in producing a high-quality mix.
As the name suggests, compression is designed to compress the dynamic range of a signal (the difference between the “loudest” and “quietest” parts of the signal).
Compression is key for helping to maintain consistent levels on a mix's main elements (often the vocal). It's also invaluable in “gluing” a mix together, helping to relate all the elements together.
Compression is often used on individual tracks/elements, buses of tracks, mix buses and even during mastering.
Using serial compression (sending a signal through multiple compressors, one after another) is an important part of getting extra perceived loudness from a track. Note that this can be done by inserting a compressor on an individual track, another on that track's bus (if applicable), and another on the mix bus.
Beyond the basics of compression, this essential processor is the centrepiece of popular production techniques such as sidechain pumping and parallel compression.
To learn more about compression, check out these in-depth resources at My New Microphone:
• The Complete Guide To Audio Compression & Compressors
• The Ultimate Audio Compressor Buyer’s Guide
Limiting is like hard compression. Rather than reducing the dynamic range by reducing the level above a set threshold, a modern limiter will have an absolute cutoff level at which no additional signal level is possible.
Limiters help tremendously in preventing hard clipping in our DAWs and help increase the loudness of the mix and individual tracks within the mix.
Equalization (EQ) is another super-important process in mixing.
EQ allows us to boost (increase the volume) or cut (decrease the volume) of specific audio frequencies.
It plays a role in the height of the mix and also in the depth (particularly with the high-frequency bands).
EQ allows us to remove rumble, noise, resonance and harshness from individual tracks and the mix as a whole while also offering the ability to enhance the characteristic tone and timbre of the elements.
Furthermore, EQ helps in separating elements, providing yet another way to ensure each individual track is well-represented in the context of the greater mix.
Distortion is often given a bad wrap, especially in the digital age, where clipping distortion can quickly ruin the clarity and quality of an otherwise perfect audio signal.
However, distortion and saturation (the two are very similar) have been ubiquitous in many of the world's greatest mixes.
Distortion refers to any change in a waveform (typically excluding amplitude/gain). Any change in a waveform causes new frequencies in the resulting sound.
Saturation is a subtle form of distortion that adds pleasant-sounding harmonics.
Saturation and distortion are inherent in analog equipment, from tape to tubes, transistors to circuits, and even in cables (to some extent).
When people talk about the sterile, bright sound of digital, they're indirectly referencing the lack of saturation and distortion.
So, saturation is key for adding warmth to a mix. The added harmonics can also really bring out the sonic character of an element.
Additionally, distorting bass-heavy sources has the effect of enhancing the upper harmonics and providing a greater perceived level (our ears are much more sensitive to mid-range frequencies than bass and sub-bass frequencies).
As the name suggests, the delay effect delays a sound. It effectively copies a signal and plays it back after the original.
Delays happen naturally in acoustic spaces as reflections off surfaces. Therefore, delay can give a sense of dimension to a mix, particularly depth (the greater the delay time, the seemingly further the source).
Stereo delay or panned delay adds width to the mix as well.
This time-based effect is essential for adding dimension and realism to a mix.
Reverb is another time-based effect responsible for mimicking the reverberation of an acoustic space. Some reverbs are designed with algorithms based on real rooms, while others are based on plate and spring technology.
Reverb is especially important for the depth dimension, with reverb times and early reflection times playing a major role in placing the source at a distance from the listener.
Another huge benefit of reverb is that it can be used to glue an entire mix together. Bus individual tracks together into a reverb and give the mix a sense that everything belongs in a defined space.
Related article: 12 Best Reverb Plugins (Spring, Plate, Algorithmic, Convolution)
Okay, maybe modulation effects aren't essential, but they do offer plenty of sonic excitement to a mix.
Modulation effects include:
Related article: Complete Guide To Audio Modulation Effects (With Examples)
A send is effectively a secondary path for a track to be sent to. This process maintains the original track (being sent to the mix bus) and adds an adjustable send amount to another track (also sent to the mix bus).
Sends allow for parallel processing and allow for easier wet/dry mixing. Additionally, multiple tracks can be routed to the same send/aux track, where a single effect insert can provide the same effect/process on all tracks.
Sends/auxes are excellent for master reverbs and delay to help establish a cohesive space for the mix to reside.
Buses are similar to sends, except the original track is no longer sent to the mix bus.
There are other terms for this type of routing, though “bus” is the most common.
This way, we can have individual tracks (with their own processes) outputted to a common bus, whereby they can all be processed together. This frees up resources and helps with the cohesiveness of the mix with common processing.
There's a lot to know about mixing. These are the essential processes within the mix, though there are plenty of other processes that go on in the grand scheme of music production.
That being said, learning the processes mentioned above will undoubtedly give you the skills to produce high-quality mixes!