In the early days of recording studios, mixing was just something that happened at the end of the session, and was sometimes called the 'remix' because it was putting the instruments back together again that had been separated in the recording process.
These days however, mixing is seen as an art form it its own right. There are now specialist mixing engineers. It is common to spend one or two days mixing just one song, and, for a mix engineer at the very top of the profession, the fee – per song – may be as much as $2000.
Mixing used to be done using a mixing console, where each track of the multitrack recording would go through one channel of the console where EQ and compression would be added. The engineer would pan all of the tracks into the stereo image, blend the fader levels, and add artificial reverberation. Just understanding how to operate the console was a skill in its own right.
Today, all of this can be done in the home recording studio with digital audio workstation software, to exactly the same level of technical quality. However, the level of artistry required is, if anything, greater than it used to be before home studios became popular. The reason is competition in the industry. Now that everyone can easily have professional tools available, there is vastly more competition among mix engineers. Inevitably, those with the determination to achieve the highest levels of knowledge, skills and experience will succeed.
The process of mixing
The process of mixing starts with playing the song through many times to understand precisely what the producer was trying to achieve, and assess the potential of the track. This stage of listening and experimentation is essential in order to understand the song. Even if you are mixing your own song, that you performed yourself in your own studio, it is likely that it has hidden potential that can be unlocked, if you are prepared to put in the work that is necessary.
During this part of the process, it may be noticed that some tracks have faults. There may be unwanted noises, clicks, awkward-sounding breaths etc. that should be edited out. Some tracks might have equalization issues, such as an excessively boomy acoustic guitar for instance. These faults should be corrected before moving on.
It should be clear by this stage of the mixing process what the most important component of the recording is. It could be the rhythm for a dance-orientated track, or it could be the lead vocal for any other kind of music. It makes sense now to work on that track and get the absolute best sound out of it, using equalization, compression, reverb and effects as necessary. When satisfied, all of the other instruments can be balanced around this one most important track. Again, a combination of equalization, compression, reverb and effects will be used, and of course the pan controls and fader levels.
The aim is to create a mix that will satisfy your client and please the buying public. Although mixing is an art form in its own right, it is only commercial success that will truly determine whether or not a mix is great, or just not good enough to put across the song as well as the song deserved.