heads. This allowed Paul to play along with a previously recorded track, both of which were mixed together on to a new track. This was a destructive process because the original recording was recorded over. Professional 8-track recorders Ampex built a handful of multitrack machines during the late 1950s that could record as many as eight tracks on tape. The project was overseen by Ross Snyder, Ampex manager of special products. To make the multitrack recorder work, Snyder invented the Sel-Sync process, which used some tracks on the head for playback and other tracks on the head for recording. This made the newly recorded material be in sync with the existing recorded tracks. The first of these machines cost $10,000 and was installed in Les Paul's home recording studio by David Sarser. In 1967, Ampex responded to demand by stepping up production of their 8-track machines with the production model MM 1000. Like earlier 8-track machines of this era, it used 1-inch tape. 16 and 24-track recorders In 1966, Ampex built their first 16-track recorder, the model AG-1000, at the request of Mirasound Studios in New York City. In 1967, Ampex introduced a 16-track version of the MM 1000 which was the world's first 16-track professional tape recorder put into mass-production. Both used a tape transport design adapted from the video recording division. The 16-track MM-1000 quickly became legendary for its tremendous flexibility, reliability and outstanding sound quality. This brought about the "golden age" of large format analog multitrack recorders which would last into the mid-1990s. MCI built the first 24-track recorder (using 2-inch tape) in 1968 which was installed at TTG Studios in Los Angeles. Later machines built by Ampex starting in 1969 would have as many as 24 tracks on 2 inch tape. In addition to this, the introduction of SMPTE time code allowed studios to run multiple machines in perfect synchronization, making the number of available tracks virtually unlimited. By the 1970s, Ampex faced tough competition from the Swiss company Studer and Japanese manufacturers such as Otari and Sony (who also purchased the MCI brand in 1982). In 1979, Ampex introduced their most advanced 24-track recorder, the model ATR-124. The ATR-124 was ruggedly constructed and had audio specifications that nearly rivaled the first digital recording machines. However, sales of the ATR-124 were slow due to the machine's high price tag. Ampex sold only about 50 or 60