Audio mixing (recorded music)

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Digital Mixing Console Sony DMX R-100 used in project studios Sony DMXR100.jpg
Digital Mixing Console Sony DMX R-100 used in project studios

In sound recording and reproduction, audio mixing is the process of combining multitrack recordings into a final mono, stereo or surround sound product. In the process of combining the separate tracks, their relative levels (i.e volumes) are adjusted and balanced and various processes such as equalization and compression are commonly applied to individual tracks, groups of tracks, and the overall mix. In stereo and surround sound mixing, the placement of the tracks within the stereo (or surround) field are adjusted and balanced. [1] :11,325,468 Audio mixing techniques and approaches vary widely and have a significant influence on the final product. [2]

Sound recording and reproduction recording of sound and playing it back

Sound recording and reproduction is an electrical, mechanical, electronic, or digital inscription and re-creation of sound waves, such as spoken voice, singing, instrumental music, or sound effects. The two main classes of sound recording technology are analog recording and digital recording.

Multitrack recording

Multitrack recording (MTR)—also known as multitracking, double tracking, or tracking—is a method of sound recording developed in 1955 that allows for the separate recording of multiple sound sources or of sound sources recorded at different times to create a cohesive whole. Multitracking became possible in the mid-1950s when the idea of simultaneously recording different audio channels to separate discrete "tracks" on the same reel-to-reel tape was developed. A "track" was simply a different channel recorded to its own discrete area on the tape whereby their relative sequence of recorded events would be preserved, and playback would be simultaneous or synchronized.

Monaural sound intended to be heard as if it were emanating from one position

Monaural or monophonic sound reproduction is sound intended to be heard as if it were emanating from one position. This contrasts with stereophonic sound or stereo, which uses two separate audio channels to reproduce sound from two microphones on the right and left side, which is reproduced with two separate loudspeakers to give a sense of the direction of sound sources. In mono, only one loudspeaker is necessary, but, when played through multiple loudspeakers or headphones, identical signals are fed to each speaker, resulting in the perception of one-channel sound "imaging" in one sonic space between the speakers. Monaural recordings, like stereo ones, typically use multiple microphones fed into multiple channels on a recording console, but each channel is "panned" to the center. In the final stage, the various center-panned signal paths are usually mixed down to two identical tracks, which, because they are identical, are perceived upon playback as representing a single unified signal at a single place in the soundstage. In some cases, multitrack sources are mixed to a one-track tape, thus becoming one signal. In the mastering stage, particularly in the days of mono records, the one- or two-track mono master tape was then transferred to a one-track lathe intended to be used in the pressing of a monophonic record. Today, however, monaural recordings are usually mastered to be played on stereo and multi-track formats, yet retain their center-panned mono soundstage characteristics.

Contents

Audio mixing techniques largely depend on music genres and the quality of sound recordings involved. [3] The process is generally carried out by a mixing engineer, though sometimes the record producer or recording artist may assist. After mixing, a mastering engineer prepares the final product for production.


A mixing engineer is a person responsible for combining ("mixing") the different sonic elements of a piece of recorded music into a final version of a song. He or she mixes the elements of a recorded piece together to achieve a good balance of volume, while at the same time deciding other properties such as pan positioning, effects, and so on.

Record producer Individual who oversees and manages the recording of an artists music

A record producer or music producer oversees and manages the sound recording and production of a band or performer's music, which may range from recording one song to recording a lengthy concept album. A producer has many, varying roles during the recording process. They may gather musical ideas for the project, collaborate with the artists to select cover tunes or original songs by the artist/group, work with artists and help them to improve their songs, lyrics or arrangements.

A mastering engineer is a person 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 streaming audio.

Audio mixing may be performed on a mixing console or digital audio workstation.

Mixing console electronic device for combining sounds of many different audio signals

In sound recording and reproduction, and sound reinforcement systems, a mixing console is an electronic device for combining sounds of many different audio signals. Inputs to the console include microphones being used by singers and for picking up acoustic instruments, signals from electric or electronic instruments, or recorded music. Depending on the type, a mixer is able to control analog or digital signals. The modified signals are summed to produce the combined output signals, which can then be broadcast, amplified through a sound reinforcement system or recorded.

Digital audio workstation electronic system designed primarily for editing digital audio

A digital audio workstation (DAW) is an electronic device or application software used for recording, editing and producing audio files. DAWs come in a wide variety of configurations from a single software program on a laptop, to an integrated stand-alone unit, all the way to a highly complex configuration of numerous components controlled by a central computer. Regardless of configuration, modern DAWs have a central interface that allows the user to alter and mix multiple recordings and tracks into a final produced piece.

History

In the late 19th century, Thomas Edison and Emile Berliner developed the first recording machines. The recording and reproduction process itself was completely mechanical with little or no electrical parts. Edison's phonograph cylinder system utilized a small horn terminated in a stretched, flexible diaphragm attached to a stylus which cut a groove of varying depth into the malleable tin foil of the cylinder. Emile Berliner's gramophone system recorded music by inscribing spiraling lateral cuts onto a vinyl disc. [4]

Thomas Edison American inventor and businessman

Thomas Alva Edison was an American inventor and businessman, who has been described as America's greatest inventor. He is credited with developing many devices in fields such as electric power generation, mass communication, sound recording, and motion pictures. These inventions, which include the phonograph, the motion picture camera, and the long-lasting, practical electric light bulb, had a widespread impact on the modern industrialized world. He was one of the first inventors to apply the principles of mass production and teamwork to the process of invention, working with many researchers and employees. He is often credited with establishing the first industrial research laboratory.

Emile Berliner German-born American inventor of the phonograph

Emile Berliner, originally Emil Berliner, was a German-born American inventor. He is best known for inventing the flat disc record and the Gramophone. He founded the United States Gramophone Company in 1894, The Gramophone Company in London, England, in 1897, Deutsche Grammophon in Hanover, Germany, in 1898, Berliner Gram-o-phone Company of Canada in Montreal in 1899, and Victor Talking Machine Company in 1901 with Eldridge Johnson.

Phonograph cylinder medium for recording and reproducing sound

Phonograph cylinders are the earliest commercial medium for recording and reproducing sound. Commonly known simply as "records" in their era of greatest popularity, these hollow cylindrical objects have an audio recording engraved on the outside surface, which can be reproduced when they are played on a mechanical cylinder phonograph. In the 1910s, the competing disc record system triumphed in the marketplace to become the dominant commercial audio medium.

Electronic recording became more widely used during the 1920s. It was based on the principles of electromagnetic transduction. The possibility for a microphone to be connected remotely to a recording machine meant that microphones could be positioned in more suitable places. The process was improved when outputs of the microphones could be mixed before being fed to the disc cutter, allowing greater flexibility in the balance. [5]

A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another.

Before the introduction of multitrack recording, all sounds and effects that were to be part of a record were mixed at one time during a live performance. If the recorded mix wasn't satisfactory, or if one musician made a mistake, the selection had to be performed over until the desired balance and performance was obtained. With the introduction of multi-track recording, the production of a modern recording changed into one that generally involves three stages: recording, overdubbing, and mixing. [6]

Overdubbing is a technique used in audio recording, whereby a musical passage is recorded two or more times. This practice can be found with singers, as well as with instruments, or ensembles/orchestras.

Modern mixing emerged with the introduction of commercial multi-track tape machines, most notably when 8-track recorders were introduced during the 1960s. The ability to record sounds into separate channels meant that combining and treating these sounds could be postponed to the mixing stage. [7]

In the 1980s, home recording and mixing became more efficient. The 4-track Portastudio was introduced in 1979. Bruce Springsteen released the album Nebraska in 1982 using one. The Eurythmics topped the charts in 1983 with the song "Sweet Dreams (Are Made of This)", recorded by band member Dave Stewart on a makeshift 8-track recorder. [8] In the mid-to-late 1990s, computers replaced tape-based recording for most home studios, with the Power Macintosh proving popular. [9] At the same time, digital audio workstations, first used in the mid-1980s, began to replace tape in many professional recording studios.

Equipment

Mixing consoles

A simple mixing console Mixing Console Discom2.jpg
A simple mixing console

A mixer (mixing console, mixing desk, mixing board, or software mixer) is the operational heart of the mixing process. [10] Mixers offer a multitude of inputs, each fed by a track from a multitrack recorder. Mixers typically have 2 main outputs (in the case of two-channel stereo mixing) or 8 (in the case of surround).

Mixers offer three main functionalities. [10] [11]

  1. Summing signals together, which is normally done by a dedicated summing amplifier or, in the case of a digital mixer, by a simple algorithm.
  2. Routing of source signals to internal buses or external processing units and effects.
  3. On-board processors with equalizers and compressors.

Mixing consoles can be large and intimidating due to the exceptional number of controls. However, because many of these controls are duplicated (e.g. per input channel), much of the console can be learned by studying one small part of it. The controls on a mixing console will typically fall into one of two categories: processing and configuration. Processing controls are used to manipulate the sound. These can vary in complexity, from simple level controls, to sophisticated outboard reverberation units. Configuration controls deal with the signal routing from the input to the output of the console through the various processes. [12]

Digital audio workstations (DAW) can perform many mixing features in addition to other processing. An audio control surface gives a DAW the same user interface as a mixing console. The distinction between a large console and a DAW equipped with a control surface is that a digital console will typically consist of dedicated digital signal processors for each channel. DAWs can dynamically assign resources like digital audio signal processing power, but may run out if too many signal processes are in simultaneous use. This overload can often be solved by increasing the capacity of the DAW. [12]

Outboard gear and plugins

Outboard gear (analog) and software plugins (digital) can be inserted into the signal path to extend processing possibilities. Outboard gear and plugins fall into two main categories: [10] [11]

Multiple level controls in signal path

A single signal can pass through a large number of level controls, e.g. individual channel fader, subgroup master fader, master fader and monitor volume control. According to audio engineer Tomlinson Holman, problems are created due to the multiplicity of the controls. Each and every console has their own dynamic range and it is important to utilize the controls correctly to avoid excessive noise or distortions. [12] :174

Processes that affect levels

These items discussed thus far affect the level of audio signal. The most commonly used process is level control, which is used even on the simplest of mixers. [12] :177

Processes that affect frequency response

There are two principle frequency response processes:

Processes that affect time

Before the advent of electronic reverb and echo processing, physical means were used to generate the effects. An echo chamber, a large reverberant room, could be equipped with a speaker and at least two spaced microphones. Signals were then sent to the speaker and the reverberation generated in the room was picked up by the two microphones, constituting a "stereo return". [13]

Processes that affect space

Mixdown

The mixdown process converts a program with a multiple-channel configuration into a program with fewer channels. Common examples include downmixing from 5.1 surround sound to stereo, and stereo to mono. In the former case, the left and right surround channels are blended with the left and right front channels. The centre channel is blended equally with the left and right channels. The LFE channel is either mixed with the front signals or not used. Because these are common scenarios, it is common practice to verify the sound of such downmixes during the production process to ensure stereo and mono compatibility.

The alternative channel configuration can be explicitly authored during the production process with multiple channel configurations provided for distribution. For example, a stereo mix can be put on DVDAudio discs or Super Audio CDs along with the surround mix. [18] Alternatively, the program can be automatically downmixed by the end consumer's audio system. For example, a DVD player or sound card may downmix a surround sound program to stereophonic sound (two channels) for playback through two speakers. [19] [20]

Mixing in surround sound

Any device having a number of multiple bus consoles (typically having eight or more buses) can be used to create a 5.1 surround sound mix, but this may be frustrating if the device is not designed to facilitate signal routing, panning and processing in a surround sound environment. Whether working in an analog hardware, digital hardware, or DAW "in-the-box" mixing environment, the ability to pan mono or stereo sources and place effects in the 5.1 soundscape and monitor multiple output formats without difficulty can make the difference between a successful or compromised mix. [21] Mixing in surround is very similar to mixing in stereo except that there are more speakers, placed to "surround" the listener. In addition to the horizontal panoramic options available in stereo, mixing in surround lets the mix engineer pan sources within a much wider and more enveloping environment. In a surround mix, sounds can appear to originate from many more or almost any direction depending on the number of speakers used, their placement and how audio is processed.

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 to mixing in surround was developed by surround mix engineer Unne Liljeblad.

Related Research Articles

Recording studio facility for sound recording

A recording studio is a specialized facility for sound recording, mixing, and audio production of instrumental or vocal musical performances, spoken words, and other sounds. They range in size from a small in-home project studio large enough to record a single singer-guitarist, to a large building with space for a full orchestra of 100 or more musicians. Ideally both the recording and monitoring spaces are specially designed by an acoustician or audio engineer to achieve optimum acoustic properties.

Surround sound

Surround sound is a technique for enriching the fidelity and depth of sound reproduction by using multiple audio channels from speakers that surround the listener. Its first application was in movie theaters. Prior to surround sound, theater sound systems commonly had three "screen channels" of sound, from loudspeakers located in front of the audience at the left, center, and right. Surround sound adds one or more channels from loudspeakers behind the listener, able to create the sensation of sound coming from any horizontal direction 360° around the listener. Surround sound formats vary in reproduction and recording methods along with the number and positioning of additional channels. The most common surround sound specification, the ITU's 5.1 standard, calls for 6 speakers: Center (C) in front of the listener, Left (L) and Right (R) at angles of 60° on either side of the center, and Left Surround (LS) and Right Surround (RS) at angles of 100–120°, plus a subwoofer whose position is not critical.

Dolby Pro Logic is a surround sound processing technology developed by Dolby Laboratories, designed to decode soundtracks encoded with Dolby Surround. Dolby Stereo was developed by Dolby in 1976 for analog cinema sound systems. The format was adapted for home use in 1982 as Dolby Surround when HiFi capable consumer VCRs were introduced. It was replaced by the improved Pro-Logic system in 1987.

Sound reinforcement system combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience

A sound reinforcement system is the combination of microphones, signal processors, amplifiers, and loudspeakers in enclosures all controlled by a mixing console that makes live or pre-recorded sounds louder and may also distribute those sounds to a larger or more distant audience. In many situations, a sound reinforcement system is also used to enhance or alter the sound of the sources on the stage, typically by using electronic effects, such as reverb, as opposed to simply amplifying the sources unaltered.

Aux-send

An aux-send is an electronic signal-routing output used on multi-channel sound mixing consoles used in recording and broadcasting settings and on PA system amplifier-mixers used in music concerts. The signal from the auxiliary send is often routed through outboard audio processing effects units and then returned to the mixer using an auxiliary return input jack, thus creating an effects loop. This allows effects to be added to an audio source or channel within the mixing console. Another common use of the aux send mix is to create monitor mixes for the onstage performers' monitor speakers or in-ear monitors. The aux send's monitor mix is usually different from the front of house mix the audience is hearing.

Panning is the distribution of a sound signal into a new stereo or multi-channel sound field determined by a pan control setting. A typical physical recording console has a pan control for each incoming source channel. A pan control or pan pot is an analog control with a position indicator which can range continuously from the 7 o'clock when fully left to the 5 o'clock position fully right. Audio mixing software replaces pan pots with on-screen virtual knobs or sliders which function like their physical counterparts.

Re-amping is a process often used in multitrack recording in which a recorded signal is routed back out of the editing environment and run through external processing using effects units and then into a guitar amplifier and a guitar speaker cabinet or a reverb chamber. Originally, the technique was used mostly for electric guitars: it facilitates a separation of guitar playing from guitar amplifier processing—a previously recorded audio program is played back and re-recorded at a later time for the purpose of adding effects, ambiance such as reverb or echo, and the tone shaping imbued by certain amps and cabinets. The technique has since evolved over the 2000s to include many other applications. Re-amping can also be applied to other instruments and program, such as recorded drums, synthesizers, and virtual instruments.

Digital mixing console

In professional audio, a digital mixing console (DMC) is an electronic device used to combine, route, and change the dynamics, equalization and other properties of multiple audio input signals, using digital computers rather than analog circuitry. The digital audio samples, which is the internal representation of the analog inputs, are summed to what is known as a master channel to produce a combined output. A professional digital mixing console is a dedicated desk or control surface produced exclusively for the task, and is typically more robust in terms of user control, processing power and quality of audio effects. However, a computer with proper controller hardware can act as the device for the digital mixing console since it can mimic its interface, input and output.

Stem mixing and mastering

Stem-mixing is a method of mixing audio material based on creating groups of audio tracks and processing them separately prior to combining them into a final master mix. Stems are also sometimes referred to as submixes, subgroups, or busses.

An audio signal is a representation of sound, typically using a level of electrical voltage for analog signals, and a series of binary numbers for digital signals. Audio signals have frequencies in the audio frequency range of roughly 20 to 20,000 Hz, which corresponds to the lower and upper limits of human hearing. Audio signals may be synthesized directly, or may originate at a transducer such as a microphone, musical instrument pickup, phonograph cartridge, or tape head. Loudspeakers or headphones convert an electrical audio signal back into sound.

Audio signal flow is the path an audio signal takes from source to output. The concept of audio signal flow is closely related to the concept of audio gain staging; each component in the signal flow can be thought of as a gain stage.

Harrison Mixbus is a digital audio workstation (DAW) available for Microsoft Windows, Mac OS X and Linux operating systems.

Focusrite British company

Focusrite plc is an English audio equipment manufacturer based in High Wycombe, England. Focusrite designs and markets audio interfaces, microphone preamps, consoles, analogue EQs and Channel strips, and digital audio processing hardware and software. Many, but not all, Focusrite products are manufactured for the company in China.

A sound card mixer is the analog part of a sound card that routes and mixes sound signals. This circuit receives inputs from both external connectors and the sound card's digital-to-analog converters. It selects or mutes, amplifies these signals, adds them together, and finally routes the result to both external output connectors and the sound card's analog-to-digital converters. Different mixing schemes are in use, but the ones implemented in most IBM-PC compatible computers today are variants of a scheme defined in Intel's AC'97 Audio Component Specification.

Matrix mixer

A matrix mixer is an audio electronics device that routes multiple input audio signals to multiple outputs. It usually employs level controls such as potentiometers to determine how much of each input is going to each output, and it can incorporate simple on/off assignment buttons. The number of individual controls is at least the number of inputs multiplied by the number of outputs.

Professional audio store

A professional audio store is a retail business that sells, and in many cases rents, sound reinforcement system equipment and PA system components used in music concerts, live shows, dance parties and speaking events. This equipment typically includes microphones, power amplifiers, electronic effects units, speaker enclosures, monitor speakers, subwoofers and audio consoles (mixers). Some professional audio stores also sell sound recording equipment, DJ equipment, lighting equipment used in nightclubs and concerts and video equipment used in events, such as video projectors and screens. Some professional audio stores rent "backline" equipment used in rock and pop shows, such as stage pianos and bass amplifiers. While professional audio stores typically focus on selling new merchandise, some stores also sell used equipment, which is often the equipment that the company has previously rented out for shows and events.

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