The Fidelipac cartridge was the first audio tape cartridge available commercially, based on the endless-loop tape cartridge design developed by Bernard Cousino in 1952, while Eash shared space in Cousino's electronics shop in the early 1950s. Instead of manufacturing the Fidelipac format himself after developing it, Eash decided to license it for manufacture to Telepro Industries, in Cherry Hill, New Jersey. Telepro then manufactured and marketed the format under the Fidelipac brand name.
Tape format
Fidelipac was originally a analog recording tape, two-track format. One of the tracks was used for monaural program audio, and the other being used for a cue track to control the player, where either a primarycue tone was recorded to automatically stop the cart, a secondary tone was recorded to automatically re-cue the cart to the beginning of the cart's program material, or a tertiary tone, which was used by some players to trigger another cart player or another form of external equipment. Later versions used three tracks, two for stereo audio, and the third for the cue track. The standard tape speed for Fidelipac carts used in the radio broadcasting industry is 7.5 ips, although some cart players and recorders can be set to record at other speeds, such as 3.75 or 15 ips.
Cartridge format
Unlike the later consumer-marketed 8-track cartridge developed later in 1964 by Bill Lear which had the pinch roller integrated in the cartridge, the Fidelipac cartridge had a hole in the right-hand bottom front corner of the cartridge, where the pinch roller, built into the player instead, would swing up into place to support the tape up against the capstan. While later machines from ATC, ITC, Harris, and others had machines where the pinch roller would automatically engage into the cartridge when the play button was pressed, early machines such as Sparta, Spot-matic, and others made the operator physically push or pull a lever to get the pinch roller in place before playback could begin. However, the 8-track was slower in speed and did not have adequate tape support pads, and thus were not "broadcast quality." The lower speed and narrower tracks in 8-track cartridges led to higher noise and poorer frequency response. The 8-track design also lacked a cue track. There were three sizes of Fidelipac carts available — the 4-inch-wide A size, which was a standard 8-track size cart with maximum minute playing time at 7.5 ips ; the 6-inch-wide B size, a larger cartridge designed for holding longer programs; and the even larger 8-inch-wide C size, often used for background music applications like the Rowe Customusic. The A size Fidelipac cartridge was later adapted by Earl "Madman" Muntz in partnership with George Eash in 1963 for his Stereo-Pak cartridge system, which differed in two ways — the number of tracks used, and the tape speed. Unlike the Fidelipac players which used a stationary head, the Stereo-Pak system used a moving headto go between the two programs.
