Oh, no question they required a different player. And not just because of the size of the cassette. Like most R-to-R machines, Sony's Elcaset machines had 3 heads, where most cassette decks of the time had only two (until Nakamichi ushered in the era of truly high-fidelity cassette decks). Plus the tape was wider, and ran at a higher speed. And like they did with the Betamax VCR decks, the tape was mechanically withdrawn from the cassette body and stabilized on capstains and rollers inside the guts of the deck, so as to reduce wow and flutter. That way the quality of the recording and playback process wasn't as the mercy of a potentially poorly made tape shell mechanism. That was an admirable effort, but I lost count of how many times I had a Betamax machine crap out on me with a tape inside of it, with no way to eject the cassette.