What is Audio Mixing?

Cutting Factory provides music or an audio soundtrack for our video productions. A very important part of making a soundtrack is the audio mixing phase, which is what a sound engineer will do after a track is recorded, often with a producer. Mixing is quite a mysterious subject for people who don’t understand how music is made, so we thought that we could break down the subject a bit and try to demystify this very complicated process. In basic terms, a mix is the process undertaken in which literally dozens of linear individual tracks, each containing one sound (acoustic or electronic) are compiled into just two tracks – commonly referred to as stereo, which is what most of us can play. (Obviously there is 5:1 for cinema and other flavours as well). During that process, the whole piece of music is balanced and enhanced, as we have attempted to describe below.

It all begins with recording or production

When audio mixing for a piece of music or an audio soundtrack begins, it begins from the very first recording and production stage. First of all, you need something to mix, and whether that’s instruments, audio fx or samples for sample based music, this is where the first consideration for the mix down begins. Why, you ask? To put it simply, a badly recorded or produced soundtrack or piece of music will produce a bad mix, because a mix engineer can only work with what they have. (whether a mix engineer is the same as the recording engineer depends on the production and team involved, it’s not always a different person).

When recording an instrument, things to take into consideration, for example, are the proximity of a microphone to the instrument. If a mix engineer is working on a recorded track where all of the instruments are recorded at a distance from the microphone, the engineer will not have much scope to add acoustics to the track in the later stages of the production. Microphones are responsive like a human ear is, so when a sound is close to the ear, it appears closer, the same with a microphone. When you have presence to work with in a recording, you also have the possibility to take it away and be more experimental with the space the instruments fit in during the mixing stage, and vice versa.

Audio software and mixing environment

Recording instruments will take place in a studio, which also houses the software that it will eventually be recorded to, called a Digital Audio Workstation (DAW). Sometimes the track will be mixed in the same location, the recording studio, and other times moved to a separate production studio for the mixing stage of the process. This can often be determined by budget, as larger recording studios cost more, and can become unnecessary for the mix as one room is only needed. One of the most important parts of the mix down is the listening environment, so things to consider before you start anything is whether you have a well acoustically-treated room, ideally have two or three sets of studio monitor speakers at your disposal (at the very minimum, a set of monitor speakers which are a high enough spec enough so you can hear the full spectrum of the frequency range in great detail).

As well as the mixing environment, the mixing tools are also important, and most of the time a good mixing engineer will be using third-party audio plugins with the DAW. What this brings to the production capabilities is more possibilities, it very often allows the mix engineer to produce a better mix, as the third party software is specially designed to have greater processing than standard audio plugins that come with a DAW.

Audio mixing techniques

When it comes to mixing a full track, there are plethora of mixing techniques a mixing engineer will use to get a song sounding loud, well balanced and full of life, too many to mention in a short blog post. The mixing techniques are nothing without the preparation that has come before, so before you step into the mix down phase, it’s important to be well prepared, part of that involves arranging a recording session or produced track into something clear and easy to follow. It can even involve adding colours to the tracks so the layout is clear, and renaming tracks so that it’s completely clear what the engineer is mixing. It also requires fixing timing issues, and pitch issues, as they will complicate the mix down process and mean that the techniques applied are not as effective.

A good engineer will approach the mix in in groups, so will start will looking at the whole recorded or produced piece of work in major sections. So all the drums are going to one group, all the guitars to another group, all the atmospheres, sound fx, vocals, basses etc to their own groups. This not only helps the engineer with the arrangement visually, but it allows the engineer to work on each group separately.

Balance

After mixing techniques have been employed, so your mixing engineer has created a great sound across all groups, a good balance is needed among all individual tracks and groups in the mix project. Certain song elements have a dedicated placement in the song’s final balance and a good mix engineer will be able to balance multiple tracks to make this balance just right. Let’s give you one example, as the human ear is much more sensitive to higher frequency audio than it is to low frequency audio content, a mix engineer should balance a track so that instruments which have these qualities are in the correct place in the mix. A bass guitar, for example, has more low frequency audio content than high, so a bass guitar should be a louder in the mix than a ride cymbal or hi hat from a drum kit, which should be much lower in the mix. Even though, over all, these instruments will sound at a similar level to each other in the final balance, they won’t actually be.

Ready for mastering

Mastering is the final stage of a tracks production and it is very often a job taken on by a separate engineer, called a mastering engineer. The job of this engineer is to take the final mix down and process the track’s loudness and tone so that the track can be played on the radio, in a club, in the cinema or on TV. Not only does being a mastering engineer require a very different skill, it also requires very different equipment. They also don’t work with between 20 to 100 track, they will often only work with two, but their job is very important because it’s the very final stage of a track production, so the end listener will hear their work as much as the mix engineers. But with a mastering engineer, they can only do their job as well as the mix engineer has done theirs, as they can only work with what they have.

Example mixes

Describing the mixing process is useful to give you and idea of what the process is like, but some audio examples can help illustrate the process. Below we have two before and after examples of tracks before the audio mixing process and after.

Above is an unmixed version of the track “Kate Crying” for an animated video by Cutting Factory. After a track with instruments is recorded in the studio, and before the mix, here is an example of what the track sounds like. Notice how everything is there, all the instruments, but it sounds messy. There’s no balance, certain instruments stand out more than others and the whole thing lacks impact.

Above is a final mix of the track “Kate Crying” for an animated video by Cutting Factory. This is after a few session of mixing with a mix engineer, notice how you can now hear everything in the mix, and there is a good balance of all of the instruments.

Next we have an early version of a track called “Good Areas”. A production without instruments will generally go through a creation stage, similar to the recording stage for music with instruments, and the mixing stage after (as described above). So here is a cut from the track after it’s first version of the mix.

After a full mix you can hear that the track has so much more life. There’s a lot more extra bass in the kick drum, seeing as it’s a techno track, this is very important. There’ also more balance overall, and the higher frequency audio content is also lower in the overall mix to suit the balance that we need (as mentioned earlier in the blog).

When audio mixing is done well, it can transform a rough track idea or recording into something that’s ready to be listened to and enjoyed by an audience. Compare it to being a good chef, as a good chef will be able to take raw ingredients and mix it into something which can also be enjoyed, and the more experienced they are, the better they are able to prepare it.