The Art of Mixing A Song

Mixing is the start of the post-production process, where separate tracks within a song are combined into a single audio file. A mixing engineer shapes and balances the different tracks in the session to sound good when played together with tools like EQ, Compression, Panning, Reverb and other FX. Mixing engineers tweak the frequency and spatial clashes between instruments, tighten grooves within frames of music and emphasize essential elements and song structures. In some cases, they might layer additional drum samples or mute parts they consider redundant.  

A Brief History

Before the advent of multi-track recording, all sounds and effects that are part of a song had to be performed live. Musicians were arranged by distance to a microphone, which was considered the most vital part of the “mix”.  If a musician made a mistake or the mix wasn’t satisfactory after playback, the selection had to be performed once again. With the advent of multi-track recording, the production of a song increased to three stages: recording, overdubbing and mixing. 

Production is the most vital and influential part of how a record will end up sounding. This means the selection and arrangement of songs and instruments, how the instruments are recorded and the takes and overdubs that make the final track. However, decades ago, post-production in the form of mixing or mastering was literally an afterthought. The differentiation between mixing and engineering only started occurring in the 1980s. Until then, the idea of hiring a separate engineer who just mixed the song was considered ridiculous. 

In the 1970s, as bands started getting more experimental with delays and reverbs, the idea of musical sound began to be created. Psych-rock bands made full use of these effects by incorporating them into the song structures. Over time, sound manipulation became a core idea of musical production. Most genres today wouldn’t be what they are without a definitive sound. Would Cher’s ‘Believe’ be the same without AutoTune? Or Daft Punk’s ‘Harder, Better, Faster Stronger’ without the vocoding? Over time, mixing has led itself to become the arrangement and customization of sound itself. 

Mixing engineers such as Bruce Swedien (5 Grammy Awards for his work with Michael Jackson) and Geoff Emerick (4 Grammy Awards, most famously with The Beatles) revolutionized engineering and mixing with their creative manipulation of sonics. Both these legends who passed away in the last couple of years paved the way for much of what we see in the area of mixing today.  

The Process

Looking at the process as part of the musical arrangement gives us a better understanding of what mixing is today. Clarity, depth, width, dynamics, frequency range and tone, are all aspects that are vital to a modern song and key to how a listener hears something for the first time. Mixers need to consider how their decisions serve the arc of a song, i.e. making the chorus hit hard enough by having the pre-chorus slightly darker and/or softer, for starters. 

Once a producer finishes a song, it is sent to a mix engineer as a full session in Pro Tools or a folder of individual stemmed out tracks. This can be a small session with eight tracks or a 100+ track session complete with vocal and instrumental doubles, multi-part harmonies and other background vocals/instruments.

A chunk of an engineer’s job in the early part is organizational in nature – labelling and colour-coding tracks, ordering them to their preference and creating instrumental groups and sub-mixes (i.e. all drums, all bass etc.). Once this is done, a mixer can move on to the more creative tasks of using the tools at their disposal, mentioned earlier, to allow the separate tracks to blend well together. Depending on the state of the song after production, a mix can take anywhere from a few hours to days. This extended time investment and critical nature of the work requires mixing engineers to develop a routine/template to keep focus and avoid ear fatigue. 

While a fully acoustically treated room that one is familiar with is great for a mix engineer, it is not as vital a requirement for mastering. Many mixers sideline as engineers and producers, moving from one studio to the next with artists. To ensure a mix translates well across different sources, they will also switch between different speakers, monitors, headphones, laptops and even cars to get different perspectives and figure out tonal balance issues. 

Equipment

Mixing may be performed on a console; however, most mixes are done either entirely or in some part on a digital audio workstation in the modern era. The tools at a mixers disposal can be broken down into four general sub-categories; affecting volume (faders, compressors and limiters), affecting frequencies (EQ and filters), affecting time (reverbs and delays) and affecting space (panning and modulation). The tools that perform these tasks can either be outboard audio processing units (i.e. analog) or audio-based plugins (i.e. digital). These processes are combined to make each element within a song and the song as a whole as audible and sonically appealing as possible. 

Most mixers work in Pro Tools, using plugins and outboard gear from a wide variety of manufacturers. Universal Audio, Soundtoys, Fabfilter and Izotope are some of the plugin manufacturers creating a new landscape with their software. Many mixers still prefer mixing on consoles, with large format SSL, Neve or API boards being preferred during a mix due to the qualities of the built-in channel strips that allow for a high degree of sonic manipulation and routing. 

Mixing to a stereo track is standard and commonplace; however, mixing to surround sound has started to gain traction over the past few years. Mixing in surround is very similar to mixing in stereo, except that there are more speakers than just left and right. In addition to the usual left and right available in stereo, mixing in surround sound lets the mixer pan wider and in a more enveloping environment. A sound can appear to originate from many more directions depending on the number of speakers used (i.e. 5.1, 7.1 etc.), their placement and how the audio is processed. However, surround sound mixing for music is not commonplace due to most, if not all, listening environments still being stereo. 

Conclusion

Once a mixer has done their work on a track and all the parties involved have approved it (i.e. artist, producer, label etc.), it is sent to a mastering engineer. We will examine and talk about mastering in the next edition of this series.