Multitracking can be achieved with
analogue recording, tape-based equipment (from simple, late-1970s cassette-based four-track Portastudios, to eight-track cassette machines, 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. Multi-track 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. With the introduction of
SMPTE timecode in the early 1970s, engineers began to use computers to perfectly synchronize separate audio and video playback, or multiple
audio tape machines. In this system, one track of each machine carried the timecode synchronization signal. Some large studios were able to link multiple 24-track machines together. An extreme example of this occurred in 1982, when the rock group
Toto recorded parts of
Toto IV on three synchronized 24-track machines. This setup allowed for 66 audio tracks, using track 24 of each machine for time code, and leaving track 23 blank to prevent interference with the audio. In the late 1970s and 1980s, digital multitrack tape machines emerged, including the 3M and Mitsubishi X-800 32-track machines, and Sony DASH PCM-3324 and later the PCM-3348 machines, which allowed greater flexibility with more available tracks for recording. As well, in order to mix using automation on the console, analogue recorders generally required adjacent tracks to the time code track to be kept blank to avoid the time code signal interfering with the audio signals, which limited available tracks to 22 or 23 track at most. Digital multitrack machines had time code inserted elsewhere on the tape, and thus did not require allocating it to an audio track, which meant all tracks were available for recording. What's more, in the case of the PCM-3348, which doubled the number of tracks from the PCM-3324, both machines could use the same ½” digital tape, and also a 24-track reel first recorded on a PCM-3324 was able to be used on a PCM-3348 and have another 24 tracks overdubbed. For computer-based systems, the trend in the 2000s is towards unlimited numbers of record/playback tracks, although issues such as
RAM memory and
CPU available do limit this from machine to machine. Moreover, on computer-based systems, the number of simultaneously available recording tracks is limited by the number of
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 and can even blend one track with two instruments to vary the music and sound options available. 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 tracks 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 mixdown, a separate set of playback heads with higher fidelity are used. Before all tracks are filled, 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. In 1963,
the Beatles were using twin track for
Please Please Me. The 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'
self-titled ninth album.
The Beach Boys'
Pet Sounds also made innovative use of multitracking with eight-track machines of the day (circa 1965).
Motown also began recording with eight-track machines in 1965, before moving to 16-track machines in mid-1969. 2340, a popular early (1973) home multitrack recorder, four tracks on ¼ inch tape D888 eight-track digital recorder 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 by making additional
takes of songs or instrumental tracks. 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. 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. ==Flexibility==