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. These tracks that are blended together are done so by using various processes such as equalization and compression. [1] Audio mixing techniques and approaches can vary widely, and due to the skill-level or intent of the mixer, can greatly affect the qualities of the sound recording. [2]

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.

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

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]

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]

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]

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 – such as an 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 this correctly to avoid excessive noise or distortions. Attacking this problem – of the correct setting for the variety of controls - can be accomplished relatively quickly. Holman refers to the scale of the control as a clue for the solution of this problem. With 0 dB being the nominal setting of the controls, many have a "gain in hand," which goes above 0 dB. This means that one can turn it up from the nominal setting to have something that sounds clear. Other controls, such as sub masters and master level controls, are used for slight trims to the overall section-by-section balance or for the main fade-ins and fade-outs of the overall mix. [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

Processes that primarily affect the frequency response of the signal are generally seen as second in importance to level control. These processes clean the audio signal, enhance interchangeability between other signals, adjust for the loudness effect, and generally create a much more pleasant or deliberately worse sound. There are two principle frequency response processes – equalization and filtering. [12] :177

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. [ citation needed ]

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. [19] 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.

References

  1. "Art of Mixing, Berklee College of Music" . Retrieved 2017-09-02.
  2. Strong, Jeff (2009). Home Recording For Musicians For Dummies (Third ed.). Indianapolis, Indiana: Wiley Publishing, Inc. p. 249.
  3. Hepworth-Sawyrr, Russ (2009). From Demo to Delivery. The production process. Oxford, United Kingdom: Focal Press. p. 109.
  4. Rumsey, Francis; McCormick, Tim (2009). Sound and Recording (6th ed.). Oxford, United Kingdom: Elsevier Inc. p. 168. ISBN   978-0-240-52163-3.
  5. Rumsey, Francis; McCormick, Tim (2009). Sound and Recording (6th ed.). Oxford, United Kingdom: Elsevier Inc. p. 169. ISBN   978-0-240-52163-3.
  6. Huber, David Miles (2001). Modern Recording Techniques. Focal Press. p. 321. ISBN   978-0240804569.
  7. "The emergence of multitrack recording". no publication date give. Retrieved June 17, 2018.Check date values in: |date= (help)
  8. "Eurythmics: Biography". Artist Directory. Rolling Stone. 2010. Retrieved March 20, 2010.
  9. "Studio Recording Software: Personal And Project Audio Adventures". studiorecordingsoftware101.com. 2008. Archived from the original on February 8, 2011. Retrieved March 20, 2010.
  10. 1 2 3 White, Paul (2003). Creative Recording (2nd ed.). Sanctuary Publishing. p. 335. ISBN   978-1-86074-456-3.
  11. 1 2 Izhaki, Roey (2008). Mixing Audio. Focal Press. p. 566. ISBN   978-0-240-52068-1.
  12. 1 2 3 4 5 6 7 8 9 10 11 Holman, Tomlinson (2010). Sound for Film and Television (3rd ed.). Oxford, United Kingdom: Elsevier Inc. ISBN   978-0-240-81330-1.
  13. 1 2 Rumsey, Francis; McCormick, Tim (2009). Sound and Recording (6th ed.). Oxford, United Kingdom: Elsevier Inc. p. 390. ISBN   978-0-240-52163-3.
  14. Levinit, Daniel J. (2004). "Instrument (and vocal) recording tips and tricks". In Greenbaum, Ken; Barzel, Ronen. Audio Anecdotes. Natick: A K Peters. pp. 147–158.
  15. Cabrera, Andrés (2011). "Pseudo-Stereo Techniques. Csound Implementations". CSound Journal. 2011 (14): Paper number 3. Retrieved 1 June 2018.
  16. Faller, Christof (2005). Pseudostereophony Revisited (PDF). Audio Engineering Society Convention 118. Barcelona. Retrieved 1 June 2018.
  17. Ziemer, Tim (2017). "Source Width in Music Production. Methods in Stereo, Ambisonics, and Wave Field Synthesis". In Schneider, Albrecht. Studies in Musical Acoustics and Psychoacoustics. Current Research in Systematic Musicology. 4. Cham: Springer. pp. 299–340. doi:10.1007/978-3-319-47292-8_10. ISBN   978-3-319-47292-8.
  18. Bartlett, Bruce; Bartlett, Jenny (2009). Practical Recording Techniques (5th ed.). Oxford, United Kingdom: Focal Press. p. 484. ISBN   978-0-240-81144-4.
  19. Huber, David Miles; Runstein, Robert (2010). Modern Recording Techniques (7th ed.). Oxford, United Kingdom: Focal Press. p. 559. ISBN   978-0-240-81069-0.
  20. "Archived copy". Archived from the original on 2012-04-02. Retrieved 2011-11-12.CS1 maint: Archived copy as title (link)
  21. "Surround Sound Mixing". www.mix-engineer.com. Retrieved 2010-01-12.