- Multitrack recording
Multitrack recording (also known as multitracking or just tracking for short) is a method of sound recording that allows for the separate recording of multiple sound sources to create a cohesive whole. Multitracking became possible with the idea of simultaneously recording different audio channels to separate discrete "tracks" on the same tape—a "track" was simply a different channel recorded to its own discrete area on tape whereby their relative sequence of recorded events would be preserved, and playback would be simultaneous or synchronized.
In the 1980s and 1990s, computers provided means by which both sound recording and reproduction could be digitized, revolutionizing audio distribution. In the 2000s, multitracking hardware and software for computers was of sufficient quality to be widely used for high-end audio recording. Though magnetic tape has not been universally replaced as a recording medium, the advantages of non-linear editing (NLE) and recording have resulted in digital systems largely superseding tape.
Multitracking can be achieved with analog recording, tape-based equipment (from simple, cassette-based four or eight trackers to 2" reel-to-reel 24-track machines), digital equipment that relies on tape storage of recorded digital data (such as ADAT eight-track machines) and hard disk-based systems often employing a computer and audio recording software. Multitrack recording devices vary in their specifications, such as the number of simultaneous tracks available for recording at any one time; in the case of tape-based systems this is limited by, among other factors, the physical size of the tape employed. Some of the biggest professional analog recording studios used a computer to synchronize multiple 24-track machines, effectively multiplying the number of available tracks into the hundreds. The rock group Toto recorded their fourth album on four computer-synced 24-track machines, for example.
For computer-based systems the trend is towards unlimited numbers of record/playback tracks, although issues such as memory and CPU available will in fact limit this from machine to machine. Moreover, on computer-based systems, the number of simultaneously available recording tracks is limited by the sound card discrete analog or digital inputs.
When recording, audio engineers can select which track (or tracks) on the device will be used for each instrument, voice, or other input.
At any given point on the tape, any of the tracks on the recording device can be recording or playing back using sel-sync or Selective Synchronous recording. This allows an artist to be able to record onto track 2 and, simultaneously, listen to track 1, 3 and 7, allowing them to sing or to play an accompaniment to the performance already recorded on these tracks. They might then record an alternate version on track 4 while listening to the other tracks. All the tracks can then be played back in perfect synchrony, as if they had originally been played and recorded together. This can be repeated until all of the available tracks have been used, or in some cases, reused. During mix down a separate set of playback heads with higher fidelity are used.
At any given point in the recording process, any number of existing tracks can be "bounced" into one or two tracks and the original tracks erased, making more room for more tracks to be reused for fresh recording. Beatles producer George Martin used this technique extensively to achieve multiple track results, while still being limited to using only multiple four-track machines, until an eight-track machine became available during the recording of the Beatles' White Album. The Beach Boys' Pet Sounds also made innovative use of multitracking with 8-track machines of the day (1965–66).
Multitrack recording also allows any recording artist to record multiple "takes" of any given section of their performance, allowing them to refine their performance to virtual perfection. A recording engineer can record only the section being worked on, without erasing any other section of that track. This process of turning the recording mechanism on and off is called "punching in" and "punching out". (See "Punch in / out".)
When recording is completed, the many tracks are "mixed down" through a mixing console to a two-track stereo recorder in a format which can then be duplicated and distributed. (Movie and DVD soundtracks can be mixed down to four or more tracks, as needed, the most common being five tracks, with an additional Low Frequency Effects track, hence the "5.1" surround sound most commonly available on DVDs.)
Most of the records, CDs and cassettes commercially available in a music store are recordings that were originally recorded on multiple tracks, and then mixed down to stereo.
In some rare cases, as when an older song is technically "updated", these stereo (or mono) mixes can in turn be recorded (as if it were a "submix") onto two (or one) tracks of a multitrack recorder, allowing additional sound (tracks) to be layered on the remaining tracks.
During multitracking, multiple musical instruments (and vocals) can be recorded, either one at a time or simultaneously, onto individual tracks, so that the sounds thus recorded can be accessed, processed and manipulated individually to produce the desired results. For example, after recording some parts of a song, an artist might listen to only the guitar part, by 'muting' all the tracks except the one on which the guitar was recorded. If one then wanted to listen to the vocals in isolation, one would do so by muting all the tracks apart from the vocals track. If one wanted to listen to the entire song, one could do so by un-muting all the tracks. If one did not like the guitar part, or found a mistake in it, and wanted to replace it, one could do so by re-recording only the guitar part (i.e., re-recording only the track on which the guitar was recorded), rather than re-recording the entire song.
If all the voices and instruments in a recording are individually recorded on distinct tracks, then the artist is able to retain complete control over the final sculpting of the song, during the mix-down (re-recording to two stereo tracks for mass distribution) phase.
For example, if an artist wanted to apply one effect to a synthesizer part, a different effect to a guitar part, a 'chorused reverb' effect to the lead vocals, and different effects to all the drums and percussion instruments, they could not do so if they had all been originally recorded together onto the same track. However, if they had been recorded onto separate tracks, then the artist could blend and alter all of the instrument's sounds with complete freedom.
Multitracking a song also leaves open the possibilities of remixes by the same or future artists, such as DJs. If the song was not available in a multitrack format recording, the job of the remixing artist could be very difficult, or impossible, because once the tracks have been re-recorded together during the mixdown phase, they are inseparable. Theoretically, one could use frequency selective filters for this, but in reality this has not been done with any great degree of success because of the multi-harmonic (having many frequencies) nature of many musical instruments and voices.
The process was conceived and developed by Ross Snyder at Ampex in 1955 resulting in the first 8-track machine which used 1-inch tape. This 8-track recorder was sold to Les Paul for $10,000. It became known as the "Octopus". Les Paul, Mary Ford and Patti Page used the technology in the late 1950s to enhance vocals and instruments. From these beginnings, it evolved in subsequent decades into a mainstream recording technique.
In the 2000s, many performers have recorded albums using only a personal computer as a tracking machine. The computer must have an analog to digital interface, and multitrack recording software must be installed. As well, a microphone is needed to record the vocals of a singer or any other sources of sound or a line-level input to accept analog signals from other equipment.
Alternatively, a standard personal computer sound card can be used to capture sounds, albeit with less fidelity. This is done simply by attaching either a microphone to the microphone input jack if a vocal track is to be recorded, or a stereo cable from the electronic device (such as a synthesizer or a guitar amplifier) to the line input of the sound card. Computers with appropriate software and hardware can record multiple audio tracks at once. This audio interface hardware sends audio signals to the computer and may interface with the computer via a PCI card, USB or FireWire connections. There are a range of audio interface options available. Popular brands include Apogee Electronics, Digidesign, Echo Digital Audio, MOTU, RME, M-Audio and Presonus. The instruments and singers' voices are recorded as individual files on the computer's hard drive, and function as tracks as per traditional multitracking. Effects such as reverb, chorus, and delays can be applied by the computer software. When the musicians are happy with the sound, the multiple tracks are mixed down onto two clean tracks, again within the multitracking software. Finally, the final stereo recording can be burned to a CD, which can be copied and distributed.
Multitracking software for a personal computer includes: Adobe Audition, Pro Tools from AVID, Pyramix from Merging Technologies, Digital Performer from Mark of the Unicorn, SONAR from Cakewalk, Samplitude from Magix, Nuendo, Cubase from Steinberg, FL Studio from Image-Line, and Logic from Apple. Mixcraft from Acoustica, Inc., REAPER from Cockos and n-Track Studio from FASoft are affordable alternatives to high end multi-track software. Audacity and Ardour are popular open source programs for multi-track recording. Jokosher (open source as well) is quite new, but seems to be gaining popularity among Linux users.
For beginners, there are several free multi-track audio recorders available online, including but not limited to Audacity and Acid Planet. While these downloadable programs lack the depth and sophistication of their more professional counterparts, they are useful for the novice, or part time artist.
Order of recording
In most modern popular songs, drums and percussion instruments are the first instruments to be recorded. There are various reasons for this. The drums are usually the rhythm leaders; it is much easier for musicians recording later tracks to keep to the common beat of the drums, also due to the precise attack of drum sounds. A drummer might find it very difficult to play along with a backing track recorded without percussion, due to the likely variations in the musicians' tempo. Furthermore, in order to accurately keep to a pre-established rhythm, a drummer would need the sound of the other instruments to be very loud to compete with their drum kit; apart from the possibility of the drum microphones picking up the sound of the other instruments from the drummer's headphones, prolonged exposure to such volume would damage their hearing. Also, it allows the drums to be recorded for a few seconds, then looped. Click (metronome) tracks are also often used as the first sound to be recorded, especially when the drummer isn't available for the initial recording, and/or the final mix will be synchronized with motion picture and/or video images. Another practical reason refers to the song key. While having the basic rhythmic track laid down, musicians can experiment with the song key (e.g. C or D). This turns useful at the writing period or when songs are meant to be performed by a not yet defined singer (e.g. music producer searching for a jingle singer).
Also, though the drums might eventually be mixed down to a couple of tracks, each individual drum and percussion instrument might be initially recorded to its own individual track. The drums and percussion combined can occupy the largest number of tracks utilized in a recording. This is done so that each percussion instrument can be processed individually for maximum effect. Equalization (or EQ) is often used on individual drums, to bring out each one's characteristic sound.
The last tracks to be recorded are usually the vocals (though a temporary vocal track might be recorded early on either as a reference or to guide subsequent musicians; this is sometimes called a "Guide Vocal", "Ghost Vocal" or "Scratch vocal"). One reason for this is that singers will often temper their vocal expression in accordance with the accompaniment.
For classical and jazz recordings (particularly instrumentals) where multitracking is chosen as the recording method (as opposed to direct to stereo, for example), a different arrangement is used; all tracks are recorded simultaneously. Sound barriers are often placed between different groups within the orchestra, e.g. pianists, violinists, percussionists, etc. When barriers are used, these groups listen to each other via headphones.
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