AFTER the car wireless came the radio cassette; after the stereo cassette came the compact disc unit. Soon, you will have an even greater choice of in-car audio entertainment. Two new digital recording formats, specifically designed for music on the move, are about to hit the high street.

Digital Compact Cassette (DCC) is seen by Philips as the logical successor to the tape cassette it invented 30 years ago. Also just launched is Sony's MiniDisc (MD), a tiny CD wrapped in a protective cartridge smaller than a computer diskette. A Sony MD car player is in the shops now, while prospective car-borne DCC buyers, won over by Philips's mega-spend on television advertising for the new cassette, will have to wait another three months. Prerecorded DCC tapes and MiniDiscs are already stocked at major record stores.

Tape cassettes have held sway in car players since Philips saw off the continuous-play cartridge more than 20 years ago. Worldwide annual sales of prerecorded cassettes peaked a few years ago at 640 million, predominantly bought for use in cars or personal stereos. The cassette's convenience is what Philips seeks to preserve in the DCC format as conventional cassette sales decline under critical aural comparison with CD.

CDs enjoy a certain vogue in cars where scanning glitches have been ironed out. Prices have tumbled to pounds 300 for a first-class CD tuner, no more than the cost of a top-flight radio cassette player. CDs have penetrated car-makers' standard-equipment lists: top models from Ford and Vauxhall, for example, sport disc machines; others have them as options.

But CDs are not cheap, cannot - yet - be recorded, and too easily suffer handling damage, while being none too easy to juggle in a car. If there is one thing that Philips and Sony agree on, it is that CDs will not assume the global mass-market status of compact cassettes.

Philips posited that the logical successor should be digital but cosily familiar. Hence DCC is tape, the cassette is the same size although a protective door covers the innards, and it is recordable on a domestic digital player (already on the market) direct from CD. Even smarter, DCC decks play all your old tapes, so there is a strong loyalty built in.

Sony started with a cleaner sheet, developed a means to cram as much digital data on to a tiny disc as is on a conventional CD (DCC needs similar compression), and wrapped it in a protective jacket. What is more, Sony developed a recordable MiniDisc using magneto-optical properties discovered about a hundred years ago. Squeezing MD into a car audio unit was no problem and, just in case rough roads do jiggle the laser, there is a four-megabyte memory - the music plays on while the scanner picks up where it broke off.

For car users, MD has many conveniences. The packs take up little space and are fully protected from scratching, dirt and sticky fingers. An autochanger player, when it leaves the drawing-board, will not be much bigger than a box of After Eights, easily fitted in the glovebox or under a seat. Access to, and repeat of, favourite tracks is rapid. DCC still suffers from mechanical winding sloth. Both formats have the added fun of album, artist and track title displays, an extra trick up the digital sleeve.

Auditions of both formats - DCC on a domestic unit and MiniDisc on the road - reveal the tremendous clarity, precision and dynamism that, hitherto, were the province of CD alone. However, MD has yet to prove to keen ears that it has the firmest grasp on stereo imaging.

Even more off-putting to less sensitive ears are the launch prices. Sony's MDX-U1 RDS car unit costs pounds 850, before adding competent amplifiers and speakers - double the cost of a comparable CD tuner. The Philips car machines will launch at prices from pounds 350 and include amplification. Prerecorded tapes and MiniDiscs cost about the same as full-price CDs - around pounds 13. Blank DCC tapes are about 10 per cent dearer than best-quality metal cassettes, but recordable MiniDiscs (maximum 74 minutes) are a telling pounds 9.

Prices may tumble and car- makers are already goggling at the potential for new digital audio equipment fitted at the factory. Right now you should, perhaps, consider your purse and review in a kinder light the familiar, if just a little imperfect, sounds of your very economical radio-cassette player.

(Photograph omitted)

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