Mixing is performed to edit and alter the recorded tracks for a song with the aim to enhance its overall musicality and structure, usually with the result of compiling multiple tracks down a regular listening format. Mixing a song will usually include the application of EQ, compression, reverb and other effects in addition to volume level mixing for each channel in the track to make it sound dynamically balanced and musical.
Mixing a song usually compiles multiple channels/tracks down a single stereo (occasionally mono) or surround sound file. This can be done digitally in Digital Audio Workstations (DAWs), through analog consoles or through a combination of the two.
A song's mix is dependent on both the quality and tone of the recordings, and their arrangement with said processing and leveling. Mix engineers are the predominant operative during the mixing stage, although there can often be input and workings from the producer if they have separate roles in the project.
Mixing nearly always incorporates the use of stem mixing to assist and streamline the mixing process.
DAWs are used for most projects, with the exception usually being full analog processing where tracks are recorded straight to tape. DAWs still work with analog outboard gear and hardware with the assistance of Analog to Digital and Digital to Analog converters – commonly referred to as AD/DA converters. Mixing can also be performed with digital hardware or with in-the-box (ITB) practices, although this will often emulate analog equipment and sounds.
Recording and mixing processes have evolved drastically over time. As recording artists and music projects grew in popularity, recording facilities became more publically available. As technology progressed through to digital domains, recording processes developed into digital workflows and further away from analog and tape.
Since the development of working with DAWs, analog signal processing and recording techniques have been incorporated into all parts of the production process, aiming to bring the best sonic qualities to the project. It is at the discretion of the artist, recording engineer, producer, mix engineer and mastering engineer as to what form of processing to use and what suits their style and the project best.
The key to a successful mix is a combination of efficiently arranged, well-recorded material, a clear vision for the overall sound of the production and good communication between all parties involved in the process.