Multitrack Recording - Process

Process

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.