Ampex and Mullin subsequently developed commercial stereo and multitrack audio recorders, based on the system originally invented by Ross Snyder of Ampex Corporation for their high-speed scientific instrument data recorders. Les Paul had been given one of the first Ampex Model 200 tape decks by Crosby in 1948, and ten years later ordered one of the first Ampex eight track "Sel Sync" machines for multitracking, (although when it arrived, it was still set up as an instrument recorder running at 60 inches-per-second and had yet to be converted for audio use). Ampex engineers, who included Ray Dolby on their staff at the time, went on to develop the first practical videotape recorders in the early 1950s to pre-record Crosby's TV shows.