Reference 1: Larry Zide, "Will the Elcaset Make It," High Fidelity's Buying Guide to Tape Systems (1978), pages 28- 30
Reference 2: "Elcaset" Hi-Fi/Stereo Buyers Guide volume 13 (January/February 1978), pages 48, 82.
The Elcaset was a cartridge tape format introduced by several Japanese electronics firms in the late 1970s for use in high fidelity audio home systems.
"Basically, Elcaset is a king size cassette [i.e. Large cassette, hence the name] measuring about six by four inches, versus about four by two and a half inches for the Philips cassette. It is three quarters of an inch thick; the Philips is a half-inch thick. The Elcaset runs at 3 3/4 ips [inches per second]; the Philips at 1 7/8 ips. " [reference two]
The Elcaset was a compromise between the all-out performance of an expensive reel-to-reel deck and the convenience of a cartridge format. The machines were heavy, sturdy devices more like professional equipment in construction than most home tape recorders. Although the tape was stored in a plastic cartridge, when it was inserted in a player a loop of tape was drawn into the workings of the machine, where the precision mechanism pulled it smoothly past the tape heads:
"In the new format the tape transport is responsible for accurate movement of the tape past the tape heads. The tape is 'pulled' out of the Elcaset and moved between guides built into the transport. In the Philips system, tape movement accuracy is controlled by guides built into the cassette." [reference two]
The tape was divided into six tracks; four were used to store two stereo music programs, the other two were control tracks used to store cueing information. Machines used a form of Dolby noise reduction and some (like the TEAC AL 700) could use optional, external Dolby units to achieve slightly better performance.
Introduced at a time when ordinary audio cassettes could not meet reel-to-reel performance, the Elcaset seemed to have some appeal for serious home recording enthusiasts. However, the machines were more expensive than high-end cassette units ($650-1200) and record companies never offered a catalog of recorded Elcasets. The machines were pulled off the market within a couple of years, following slow sales.
Models actually offered for sale included the JVC LD-777 ($800), the Sony EL-5 and EL-7 ($630 and $880), the TEAC AL-700 ($1100), and the Technics RS-7500US ($650). Marantz announced a line of Elcaset recorders, but I have not confirmed that they actually were offered.
IEEE Center for the History of Electrical Engineering