David Dintenfass kindly sent me an article from the October 1959 issue of Popular Electronics which says, in part, that RCA plans to have 65 titles in the stores in their new cartridges by Christmas 1959. Other manufacturers were shown to be making compatible players.

The article also heralded this as the saviour of tape, and talked about the “old” two-track format running at 7.5 in/s — the cartridges ran at 3.75 in/s (and on some models 1.88 in/s was also available). It goes on to say later that 7.5 in/s quarter track tapes are still a high-fidelity medium. The article referred to cartridges and quarter-track reels as the “one-two punch” against stereo records which seemed to take over from the two-track pre-recorded tapes. The open-reel tape at 7.5 in/s would be the “only choice for the quality-conscious stereophile” since the cartridges were only available in 3.75 in/s versions.

There was no mention of the later name “Sound Tape” in the article, but that appears to be the semi-official if not official name of this format. Thanks to Bill Schuh for that piece of information. Bill also provided a link to The Tape Place which specializes in out-of-print commercial tape releases. I have not used The Tape Place, so this is just being passed on, not a personal recommendation.

The Sound Tape cartridges used the standard 1/4-track interleaved format which prevailed for a decade as the consumer open-reel format.

Details about these formats can be found here and here in the Formats and Resources subset of this website.