Recording Studios: Multitrack Recording
The next major development in recording studios was multitrack recording, in which the tape is divided into multiple tracks parallel with each other. Because they are carried on the same medium, the tracks stay in perfect synchronization. The first development in multitracking was stereo sound, which divided the recording head into two tracks. First developed by German audio engineers ca. 1943 in German recording studios, 2-track recording was rapidly adopted for modern music in the 1950s because it enabled signals from two or more separate microphones to be recorded simultaneously, enabling stereophonic recordings to be made and edited conveniently in recording studios. (The first stereo recordings, on disks, had been made in the 1930s, but were never issued commercially.) Stereo (either true, 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 monophonic sound until the mid-1960s.
Much of the credit for the development of multitrack recording goes to guitarist, composer and technician Les Paul, who also helped design the famous electric guitar that bears his name. 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, were 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 taped and record new parts in time alongside them. This was quickly adopted by recording studios.
Multitrack recording was immediately taken up in a limited way by Ampex, who soon produced a commercial 3-track recorder. 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 Ampex 3-track recorders. Engineer Tom Dowd was among the first to use multitrack recording for popular music production in recording studios while working for Atlantic Records during the 1950s.
The next important development was 4-track recording. The advent of this improved system gave recording studios and musicians vastly greater flexibility for recording and overdubbing, and 4-track was the studio standard for most of the later 1960s. Many of the most famous recordings by The Beatles and The Rolling Stones were recorded on 4-track, and the engineers at London’s Abbey Road Studios became particularly adept at a technique called “reduction mixes” in the UK and “bouncing down” in the United States, in which several tracks were recorded onto one 4-track machine and then mixed together and transferred (bounced down) to one track of a second 4-track machine. In this way, it was possible to record literally dozens of separate tracks and combine them into finished recordings of great complexity.
All of the Beatles classic mid-1960s recordings, including the albums Revolver and Sgt. Pepper’s Lonely Hearts Club Band, were recorded in this way. There were limitations, however, because of the build-up of noise during the bouncing-down process, and the Abbey Road engineers are still famed for their ability to create dense multitrack recordings while keeping background noise to a minimum.
4-track tape also enabled the development of quadraphonic sound, in which each of the four tracks was used to simulate a complete 360-degree surround sound. A number of albums were released both in stereo and quadrophonic format in the 1970s, but ‘quad’ failed to gain wide commercial acceptance. Although it is now considered a gimmick, it was the direct precursor of the surround sound technology that has become standard in many modern home theatre systems.
In a professional setting today, such as a studio, audio engineers may use 24 tracks or more for their recordings, using one or more tracks for each instrument played.
The combination of the ability to edit via tape splicing and the ability to record multiple tracks revolutionized studio recording. It became common studio recording practice to record on multiple tracks, and bounce down afterward. The convenience of tape editing and multitrack recording led to the rapid adoption of magnetic tape as the primary technology for commercial musical recordings. Although 33⅓ rpm and 45 rpm vinyl records were the dominant consumer format, recordings were customarily made first on tape, then transferred to disc, with Bing Crosby leading the way in the adoption of this method in the United States.