Audio mixing (recorded music)
Encyclopedia
In audio recording, audio mixing is the process by which multiple recorded sounds are combined into one or more channels, most commonly two-channel stereo
. In the process, the source signals' level, frequency content, dynamics, and panoramic position are manipulated and effects such as reverb may be added. This practical, aesthetic, or otherwise creative treatment is done in order to produce a mix that is more appealing to listeners.
Audio mixing is done in studios as part of creating an album or single. The mixing stage often follows multitrack recording
and the final mixes are normally submitted to a mastering engineer
. The process is generally carried out by a mix engineer
, also called mixing engineer, or mixer, though sometimes it is the musical producer, or even the artist, who mixes the recorded material.
Prior to the emergence of digital audio workstations (DAWs), the process of mixing used to be carried out on a device known as an audio mixer, sound board, desk, or mixing console
. Nowadays, more and more engineers and independent artists are using a personal computer
for the process (commonly referred to as mixing in-the-box). Mixing consoles still play a large part in the recording process. They are often used in conjunction with a DAW, although the DAW may only be used as a multitrack recorder and for editing or sequencing, with the actual mixing being performed on the console.
However, as Chicarelli explains, sometimes limited budgets dictate that a producer takes care of the mixing as well.
, most notably the 8-track recorders that were introduced during the 1960s. The ability to record sounds into a multitude of channels meant that treating these sounds can be postponed to a later stage – the mixing stage.
In the 1980s, home recording and mixing began to take market share from recording studios. The 4-track Portastudio
was introduced in 1979. Using one, Bruce Springsteen
released the album Nebraska
in 1982. The Eurythmics
topped the charts in 1983 with the song "Sweet Dreams (Are Made of This)
", recorded by bandmember Dave Stewart
on a makeshift 8-track recorder. In the mid-to-late 1990s, computers replaced tape-based recording for most home studios, with the Power Macintosh
proving popular. At the same time, digital audio workstation
s (DAW), first used in the mid-1980s, began to replace tape in many professional recording studios.
, or mixing desk, or mixing board, or software mixer is the operational heart of the mixing process. Mixers offer a multitude of inputs, each is fed by a track from a multitrack recorder; mixers would normally have 2 main outputs (in the case of two-channel stereo mixing) or 8 (in the case of surround).
Mixers offer three main functionalities:
Common classes:
is very similar to mixing in stereo except that there are more speakers, placed to 'surround' the listener. The same mixing domains mentioned above are involved, but instead of stereo's horizontal panoramic aspects, and depth's front-back aspects, mixing in surround lets the mix engineer
pan sources within a much more two dimensional environment. In a surround mix, sounds can appear to originate from any direction.
There are two common ways to approach mixing in surround:
Naturally, these two approaches can be combined any way the mix engineer
sees fit. Recently, a third approach, or method of mixing in surround was developed by surround mix engineer
Unne Liljeblad.
Stereophonic sound
The term Stereophonic, commonly called stereo, sound refers to any method of sound reproduction in which an attempt is made to create an illusion of directionality and audible perspective...
. In the process, the source signals' level, frequency content, dynamics, and panoramic position are manipulated and effects such as reverb may be added. This practical, aesthetic, or otherwise creative treatment is done in order to produce a mix that is more appealing to listeners.
Audio mixing is done in studios as part of creating an album or single. The mixing stage often follows multitrack recording
Multitrack recording
Multitrack recording is a method of sound recording that allows for the separate recording of multiple sound sources to create a cohesive whole...
and the final mixes are normally submitted to a mastering engineer
Mastering engineer
A mastering engineer is one skilled in the practice of taking audio that has been previously mixed in either the analog or digital domain as mono, stereo, or multichannel formats and preparing it for use in distribution, whether by physical media such as a CD, vinyl record, or as some method of...
. The process is generally carried out by a mix engineer
Mix engineer
A mix engineer, also referred to as "mixing engineer", is a person who, once all instruments, voices, and sounds, etc., have been recorded, creates what is called the final version of a song, hence the term "mix engineer"...
, also called mixing engineer, or mixer, though sometimes it is the musical producer, or even the artist, who mixes the recorded material.
Prior to the emergence of digital audio workstations (DAWs), the process of mixing used to be carried out on a device known as an audio mixer, sound board, desk, or mixing console
Mixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
. Nowadays, more and more engineers and independent artists are using a personal computer
Personal computer
A personal computer is any general-purpose computer whose size, capabilities, and original sales price make it useful for individuals, and which is intended to be operated directly by an end-user with no intervening computer operator...
for the process (commonly referred to as mixing in-the-box). Mixing consoles still play a large part in the recording process. They are often used in conjunction with a DAW, although the DAW may only be used as a multitrack recorder and for editing or sequencing, with the actual mixing being performed on the console.
The role of audio mixing
The role of music producer is not necessarily a technical one, with the physical aspects of recording being assumed by the audio engineer, and so producers often leave the similarly technical mixing process to a specialist audio mixer. Even producers with a technical background may prefer that a mixer comes in to take care of the final stage of the production process. Noted producer and mixer Joe Chiccarelli has said that it is often better for a project that an outside person comes in because:"when you're spending months on a project you get so mired in the detail that you can't bring all the enthusiasm to the final [mixing] stage that you'd like. [You] need somebody else to take over those responsibilities so that you can sit back and regain your objectivity."
However, as Chicarelli explains, sometimes limited budgets dictate that a producer takes care of the mixing as well.
History
Mixing as we know it today emerged with the introduction of commercial multitrack tape machinesMagnetic tape sound recording
The use of magnetic tape for sound recording originated around 1930. Magnetizable tape revolutionized both the radio broadcast and music recording industries. It did this by giving artists and producers the power to record and re-record audio with minimal loss in quality as well as edit and...
, most notably the 8-track recorders that were introduced during the 1960s. The ability to record sounds into a multitude of channels meant that treating these sounds can be postponed to a later stage – the mixing stage.
In the 1980s, home recording and mixing began to take market share from recording studios. The 4-track Portastudio
Portastudio
The TASCAM Portastudio was the world's first four track recorder based on a standard compact audio cassette tape.When the original Portastudio 144 made its debut in 1979 it was a revolutionary creative tool...
was introduced in 1979. Using one, Bruce Springsteen
Bruce Springsteen
Bruce Frederick Joseph Springsteen , nicknamed "The Boss," is an American singer-songwriter who records and tours with the E Street Band...
released the album Nebraska
Nebraska (album)
-Themes:The album begins with "Nebraska", a first-person narrative based on the true story of 19-year-old spree killer Charles Starkweather and his 14-year-old girlfriend, Caril Ann Fugate, and ends with "Reason to Believe", a complex narrative that renders its title phrase into contemptuous sarcasm...
in 1982. The Eurythmics
Eurythmics
Eurythmics were a British pop rock duo, formed in 1980, currently disbanded, but known to reunite from time to time. Consisting of members Annie Lennox and David A...
topped the charts in 1983 with the song "Sweet Dreams (Are Made of This)
Sweet Dreams (Are Made of This)
-Personnel:*Annie Lennox – vocals, keyboards, synthesisers, flute*David A. Stewart – guitar, keyboards, synthesisers, programming, backing vocals-Additional personnel:*Robert Crash - Guitar/ E-Drums/ Synth/ Robotic vocals...
", recorded by bandmember Dave Stewart
David A. Stewart
David Allan Stewart , often known as Dave Stewart, is an English musician, songwriter and record producer, best known for his work with Eurythmics. He is usually credited as David A. Stewart, to avoid confusion with other musicians named "Dave Stewart".-Early life:Stewart was born in Sunderland,...
on a makeshift 8-track recorder. In the mid-to-late 1990s, computers replaced tape-based recording for most home studios, with the Power Macintosh
Power Macintosh
Power Macintosh, later Power Mac, was a line of Apple Macintosh workstation-class personal computers based on various models of PowerPC microprocessors that were developed, marketed, and supported by Apple Inc. from March 1994 until August 2006. The first models were the Power Macintosh 6100,...
proving popular. At the same time, digital audio workstation
Digital audio workstation
A digital audio workstation is an electronic system designed solely or primarily for recording, editing and playing back digital audio. DAWs were originally tape-less, microprocessor-based systems such as the Synclavier and Fairlight CMI...
s (DAW), first used in the mid-1980s, began to replace tape in many professional recording studios.
Mixers
A mixer, or mixing consoleMixing console
In professional audio, a mixing console, or audio mixer, also called a sound board, mixing desk, or mixer is an electronic device for combining , routing, and changing the level, timbre and/or dynamics of audio signals. A mixer can mix analog or digital signals, depending on the type of mixer...
, or mixing desk, or mixing board, or software mixer is the operational heart of the mixing process. Mixers offer a multitude of inputs, each is fed by a track from a multitrack recorder; mixers would normally have 2 main outputs (in the case of two-channel stereo mixing) or 8 (in the case of surround).
Mixers offer three main functionalities:
- Mixing – summing signals together, which is normally done by a dedicated summing amplifier or in the case of digital by a simple algorithm.
- Routing – allows the routing of source signals to internal buses or external processing units and effects.
- Processing – many mixers also offer on-board processors, like equalizers and compressors.
Outboard gear and plugins
Outboard gear (analog) and software plugins (digital) can be inserted to the signal path in order to extend processing possibilities. Outboard gear and plugins fall into two main categories:- Processors – these devices are normally connected in series to the signal path, so the input signal is replaced with the processed signal (e.g. equalizers).
- Effects – while an effect can be considered as any unit that affects the signal, the term is mostly used to describe units that are connected in parallel to the signal path and therefore they add to the existing sounds, but do not replace them. Examples would include reverb and delay.
Common classes:
- Processors:
- Faders – used to attenuate or boost the level of signals.
- Pan pots – used to pan signal to the left or right and in surround also back and front.
- Equalizers – used to manipulate the frequency content of signals.
- Compressors – used to manipulate the dynamic content of signals. Among many applications they can even the level fluctuations of a singer, or reshape dynamic envelopes of percussive instruments (e.g. adding attack to a snare).
- Gates – used mainly to attenuate low-level signals, for example, the kick spill on a snare recording.
- Effects:
- ReverbsReverberationReverberation is the persistence of sound in a particular space after the original sound is removed. A reverberation, or reverb, is created when a sound is produced in an enclosed space causing a large number of echoes to build up and then slowly decay as the sound is absorbed by the walls and air...
– used to simulate the boundary reflection created in a real room, but that adding a sense of space to otherwise 'dry' recordings. - DelaysDelay (audio effect)Delay is an audio effect which records an input signal to an audio storage medium, and then plays it back after a period of time. The delayed signal may either be played back multiple times, or played back into the recording again, to create the sound of a repeating, decaying echo.-Early delay...
– most commonly used to add distinct echoes as a creative effect.
- Reverbs
Mixing Domains
The process of mixing often accounts for a few mixing domains:- Level – concerned with the relative level between instruments and their dynamics.
- Frequency – concerned with the spectral content of the various instruments and the overall mix.
- Space – concerned with the spatial aspect of the various instruments. The space domain is often further subdivided into two sub-domains:
- Stereo – concerned with the horizontal panoramic (left/right) aspects of instruments.
- Depth – concerned with the front-back aspects of instruments.
Mixing in Surround
Mixing in surroundSurround sound
Surround sound encompasses a range of techniques such as for enriching the sound reproduction quality of an audio source with audio channels reproduced via additional, discrete speakers. Surround sound is characterized by a listener location or sweet spot where the audio effects work best, and...
is very similar to mixing in stereo except that there are more speakers, placed to 'surround' the listener. The same mixing domains mentioned above are involved, but instead of stereo's horizontal panoramic aspects, and depth's front-back aspects, mixing in surround lets the mix engineer
Mix engineer
A mix engineer, also referred to as "mixing engineer", is a person who, once all instruments, voices, and sounds, etc., have been recorded, creates what is called the final version of a song, hence the term "mix engineer"...
pan sources within a much more two dimensional environment. In a surround mix, sounds can appear to originate from any direction.
There are two common ways to approach mixing in surround:
- Expanded Stereo – With this approach, the mix will still sound very much like an ordinary stereo mix. Most of the sources such as the instruments of a band, the vocals, and so on, will still be panned between the left and right speakers, but lower levels might also be sent to the rear speakers in order to create a wider stereo image, while lead sources such as the main vocal might be sent to the center speaker. Additionally, reverb and delay effects will often be sent to the rear speakers to create a more realistic sense of space. In the case of mixing a live recording that was performed in front of an audience, signal recorded by microphones aimed at, or placed among the audience will also often be sent to the rear speakers to make the listener feel as if he or she is in the crowd.
- Complete Surround / All Speakers Are Treated Equally – Instead of following the traditional ways of mixing in stereo, this much less conservative approach lets the mix engineerMix engineerA mix engineer, also referred to as "mixing engineer", is a person who, once all instruments, voices, and sounds, etc., have been recorded, creates what is called the final version of a song, hence the term "mix engineer"...
do anything he or she feels like. Instruments can appear to originate from anywhere, or even spin around the listener. When done tastefully, interesting sonic experiences can be achieved, as was the case with James GuthrieJames GuthrieJames Guthrie was a U.S. Senator from Kentucky and served as Secretary of the Treasury in the administration of President Franklin Pierce.- Early life :...
's 5.1 mix of Dark Side of the Moon.
Naturally, these two approaches can be combined any way the mix engineer
Mix engineer
A mix engineer, also referred to as "mixing engineer", is a person who, once all instruments, voices, and sounds, etc., have been recorded, creates what is called the final version of a song, hence the term "mix engineer"...
sees fit. Recently, a third approach, or method of mixing in surround was developed by surround mix engineer
Mix engineer
A mix engineer, also referred to as "mixing engineer", is a person who, once all instruments, voices, and sounds, etc., have been recorded, creates what is called the final version of a song, hence the term "mix engineer"...
Unne Liljeblad.
- MSS – Multi Stereo Surround – This approach treats the speakers in a surround sound system as a multitude of stereo pairs. For example, a stereo recording of a piano, created using two microphones in an ORTF configurationORTF stereo techniqueThe ORTF stereo microphone system is a microphone technique used to record stereo sound.It was devised around 1960 at the Office de Radiodiffusion Télévision Française at Radio France....
, might have its left channel sent to the Left Rear Speaker and its right channel sent to the Center Speaker. The piano might also be sent to a reverb having its left and right outputs sent to the Left Front Speaker and Right Rear Speaker respectively. Additional elements of the song, such as an acoustic guitar recorded in stereo, might have its left and right channels sent to the Left Front Speaker and the Right Rear Speaker with a reverb returning to the Left Rear Speaker and the Center Speaker. Thus, multiple clean stereo recordings surround the listener without the smearing comb filtering effects that often occurs when the same or similar sources are sent to multiple speakers.