Multitrack recording of sound is the process in which sound and other electro-acoustic signals are captured on a recording medium such as magnetic tape, which is divided into two or more audio tracks that run parallel with each other. Because they are carried on the same medium, the tracks stay in perfect synchronization, while allowing multiple sound sources to be recorded at different times.
The first system for creating stereophonic sound (using telephone technology) was demonstrated by Clément Ader in Paris in 1881. The pallophotophone, invented by Charles A. Hoxie and first demonstrated in 1922, recorded optically on 35 mm film. Some versions used a format of as many as twelve independent monaural tracks in parallel on each strip. Each track was recorded one at a time in separate passes and were not intended for later mixdown or stereophony because each monophonic program was unrelated to the next - any more than one random album would be related to the next. Unlike with later half-track and quarter-track monophonic tape recording, the multiple tracks simply multiplied the maximum recording time possible, greatly reducing cost and bulk.
Alan Blumlein, a British engineer at EMI, patented systems for recording stereophonic sound and surround sound on disc and film in 1933. The history of modern multitrack audio recording using magnetic tape began in 1943 with the invention of stereo tape recording, which divided the recording head into two tracks. In 1948, Chicago's Armour Research Foundation announced that its staffer, physicist Marvin Camras, had produced a three-channel machine with "three parallel magnetic tracks on the same tape"."3-Dimensional Tape Recording Set by Camras." Billboard, 22 May 1948, 25.
The next major development in multitrack recording came in the mid-1950s, when the Ampex corporation devised the concept of 8-track recording, using its "Sel-Sync" (Selective Synchronous) recording system, and sold the first such machine to musician Les Paul.ARSC Journal, Sel-sync and the "Octopus": How Came to be the First Recorder to Minimize Successive Copying in Overdubs. Audio Engineering Society. However, for the next 35 years, multitrack audio recording technology was largely confined to specialist radio, TV and music recording studios, primarily because multitrack tape machines were both very large and very expensive – the first Ampex 8-track recorder, installed in Les Paul's home studio in 1957, cost US$10,000 – roughly three times the US average yearly income in 1957, and .
Affordable home multitrack recorders using magnetic tape were introduced in the 1970s. In 1979, the introduction of the TASCAM Portastudio presented a novel format of four tracks running in the same direction and doubled tape speed for the compact audio cassette as its medium, making good-quality four-track multitrack recording available to the average consumer for the first time. TASCAM and Fostex soon introduced reel-to-reel multitrack recorders that also boosted the number of tracks relative to the width of the magnetic tape, such as eight tracks on ¼-inch tape. By then, electronics companies were already introducing digital audio recording systems that used analog magnetic tape as storage media for the digital multitrack data.
By the 1990s, computer-based digital multitrack recording systems such as Pro Tools and Cubase were being adopted by the recording industry, and soon became standard. By the early 2000s, rapid advances in home computing and digital audio software were making digital multitrack audio recording systems available to the average consumer, and high-quality digital multitrack recording systems like GarageBand were being included as a standard feature on home computers.
Overview Stereo sound recording on tape was perfected in 1943 by German audio engineers working for the AEG corporation. Around 250 stereo tape recordings were made during this period (of which only three have survived), but the technology remained a closely guarded secret within Germany until the end of World War II. After the war, American audio engineer John T. Mullin and the Ampex corporation pioneered the commercial development of tape recording in the US, and the technology was rapidly taken up by radio and the music industry due to its superior sound fidelity and because tape – being a linear recording medium – could be easily edited, by physically cutting and splicing the tape, to remove unwanted elements and create a 'perfect' recording. Two-track tape recording was rapidly adopted for modern music in the early 1950s because it enabled signals from two or more separate microphones to be recorded simultaneously, enabling both twin-track mono recordings (with the voices on one and music on the other) as well as true stereophonic recordings to be made and edited conveniently, which in turn facilitated the rapid expansion of the consumer high-fidelity ("HiFi") market. Stereo (either true binaural two-microphone stereo or multimixed) quickly became the norm for commercial classical recordings and radio broadcasts, although many pop music and jazz recordings continued to be issued in mono sound until the late 1960s.
Much of the credit for the development of multitrack recording goes to guitarist, composer and technician Les Paul, who lent his name to Gibson's first solid-body electric guitar. His experiments with tapes and recorders in the early 1950s led him to order the first custom-built eight-track recorder from Ampex, and his pioneering recordings with his then wife, singer Mary Ford. But it was Patti Page who was the first vocalist to record her own voice, sound on sound, with a song called "Confess", in 1947: Bill Putnam, an engineer for Mercury Records, was able to overdub Page's voice, due to his well-known use of technology.
Mercury was not a large label at the time, and although tape recording had been adopted in Los Angeles earlier in 1947, studios in Chicago were not yet equipped with mono tape technology, let alone multitrack equipment. This session involved recording the orchestra and Page's 4th background vocal onto one lacquer in one pass, playing back the lacquer for her to sing over the top of that with the 3rd background vocal and so on with the main vocal being the last pass Ed Condit - History of Stereophonic Sound (1959) utilizing the same technique Les Paul had been experimenting with since the early 1930s.
Thus, although Page became the first pop artist to overdub her vocals on a song, the practice had been utilized with instruments for several years. This was months before Les Paul and Mary Ford had their first multi-voiced release. Paul was the first to make use of the technique of multitracking to record separate elements of a musical piece asynchronously – that is, separate elements could be recorded at different times. Paul's technique enabled him to listen to the tracks he had already cut and record new parts in time alongside them onto first disc and then tape. In 1963, solo jazz pianist Bill Evans recorded Conversations with Myself, an innovative solo album using the unconventional (in jazz solo recordings) technique of overdubbing over himself, in effect creating a two-piano duet of jazz improvisations.
Despite Ampex having created the first eight-track tape machines for Les Paul and Atlantic Records, multitrack recording was taken up in a more limited way in the industry via three-track recorders. These proved extremely useful for popular music, since they enabled backing music to be recorded on two tracks (either to allow the overdubbing of separate parts, or to create a full stereo backing track) while the third track was reserved for the lead vocalist. Three-track recorders remained in widespread commercial use until the mid-1960s and many famous pop recordings – including many of Phil Spector's so-called "Wall of Sound" productions and early Motown hits – were taped on 3-track recorders.
A great many of those utilized multiple 3-track sources with the basic band being recorded on the first three, that being mixed down to mono and "flown over" to a second 3-track, leaving two open. The process was repeated for sidemen, soloists, background singers and any number of other elements before the last track on the last recording stage was used for the lead vocal.
The next evolution was four-track recording, which was the studio standard through the mid 1960s. Many of the most famous recordings by the Beatles and the Rolling Stones were recorded on four-track, and the engineers at London's Abbey Road Studios became particularly adept at the technique called "reduction mixes" in the UK and "bouncing down" in the United States, described in the paragraph above. In this way, it was possible to record literally dozens of separate tracks and combine them into finished recordings of great complexity.
With modern digital sync technology, it is often possible to re-sync all these multiple stage tapes into something loosely resembling a modern 16-track or 24-track session and make it appear as if everything had been recorded onto the same tape, from which a new modern remix could then be performed.
By the mid-1960s, the ready availability of the most up-to-date multitrack recorders – which were by then standard equipment in the leading Los Angeles recording studios – enabled Brian Wilson of the Beach Boys to become one of the first pop producers to exploit the huge potential of multitrack recording. During the group's most innovative period of music-making, from 1964 to 1967, Wilson developed elaborate techniques for assembling the band's songs, which combined elements captured on both four-track and eight-track recorders, as well as making extensive use of tape editing.
By 1964, Wilson's increasingly complex arrangements had far outstripped the group's limited musical abilities – singer-guitarist Carl Wilson was the only group member who regularly contributed to these tracking sessions – so Wilson began frequently recording all the instrumental backing tracks for his songs using the team of top-rank professional studio musicians who came to be known as "The Wrecking Crew", but the band themselves still recorded the instrumental backing for certain songs. For the group's landmark Pet Sounds album in 1966, Wilson recorded all the album's elaborate backing tracks using The Wrecking Crew and other session musicians, while the Beach Boys were away touring, but on the song "That's Not Me", the Beach Boys themselves played on the instrumental backing; the session musicians typically performed these instrumental tracks as ensemble performances, which were recorded and mixed live, direct to a 4-track recorder.
When the other Beach Boys returned from touring, they moved to Columbia's Hollywood studio, which was equipped with the latest eight-track technology; by this time, Wilson and his engineers had 'reduced' the pre-recorded four-track backing tracks to a mono mix, which was then dubbed onto one track of the eight-track master tape; Wilson then recorded the vocal tracks, assigning one individual track to each of the six vocalists (including soon-to-be permanent member Bruce Johnston), leaving the eighth track available for final 'sweetening' elements, such as additional vocal or instrumental touches, and lastly, all these elements were mixed down to the mono master tape. Nearly all of the Beach Boys' four-track and eight-track masters from this period are preserved in Capitol's archive, allowing the label to release several expansive boxed sets of this music; The Pet Sounds Sessions (1997) includes nearly all the separate backing and vocal tracks from the album, as well as new stereo mixes of all the songs, while the nine-CD The Smile Sessions (2011) features a wide cross-section of the huge amount of instrumental and vocal material (totalling around 50 hours of recordings) that was recorded for the group's never-completed 1967 magnum opus Smile.