DCC AND MD: TECHNO-TOYS?

The home entertainment industry is about to undergo radical changes. By January, both the Philips Digital Compact Cassette (DCC) and the Sony MiniDisc (MD) should be widely available in this country. In addition, digital signal processing is poised to become the predominant technology in various audio and video control devices, as well as in a number of loudspeaker applications.

Both DCC and MD depend heavily on bit-rate reduction systems, which are but the first harbingers of similar data-compression systems that will be used in a broad variety of other audio and video products. For example, HDTV systems under consideration by the FCC use some form of data compression.

Needless to say, many people take a skeptical view of data compression, especially with respect to audio equipment; they believe that data compression will de grade sound quality. One main concern seems to be audibility of the Precision Adaptive Sub-band Coding (PASC) used in DCC recorders. Preliminary reports (mainly from Europe) on several DCC prototypes were rather mixed. The reviewers were careful to distinguish between what they thought would be acceptable to the public and what far more critical audiophiles would accept. In a comparison be tween a prerecorded DCC and a CD of the same program, there was general agreement that differences in sound quality were perceptible though "slight" or "subtle," with the CD sound having perhaps a shade "more openness and ambience." A few critics were less charitable. One stated that DCC was "clearly inferior to CD-the PASC is not transparent." Another said the opposite, claiming to be "surprised by the transparency of the PASC." DCC decks have backward compatibility-they can play standard analog cassettes-but at present they cannot record analog cassettes. The analog playback quality from these early DCC machines did not impress the reviewers, who in the main considered it "marginal." Sifting through the comments, I'd say it appears that only the hypercritical audiophile, with a high-resolution playback system will regard the Digital Compact Cassette as a sonically inferior format. Ironically, one digiphobe who has maligned the Compact Disc now speaks reverentially of the "wonderfully cohesive, smooth sound and musicality of 16-bit linear PCM CDs" as compared to DCC! Entry-level DCC recorders are expected to cost between $700 and $900, with 60-minute blank DCC tapes running about $8 to $9. This is obviously a bit pricey, but the anticipation is that the cost will be appreciably less in a relatively short time, as was the case with CD. As for prerecorded DCC tapes, there seems to be some confusion as to what they will cost. Philips had hoped to sell a DCC for less than a CD, and then it appeared that the prices would be the same. Some re ports circulated that a DCC recording would be more expensive than a CD, but I tend to discount this, as it would be a very significant obstacle to acceptance of the new format. All of the technology for Digital Compact Cassette tape duplication seems to be in place, with some 500 titles expected to be available.

The MiniDisc, with its Adaptive TRansform Acoustic Coding (ATRAC) data-compression system, permits up to 74 minutes of digital recording on its 2 1/2-inch disc, employing magneto-optical technology. Sony claims the MD provides sound of "near CD quality." The MDs allow a virtually unlimited number of record/playback/erase cycles and, like CDs, offer quick random access to program material. Targeted to the personal-portable Walkman/ Discman market, the MD format allows joggers to enjoy music virtually uninterrupted, since the Electronic Shock Protection (ESP) memory buffer now pro vides 10 S of playback for the laser to resume proper tracking, instead of the 3 S of the original design.

Sony's MD units will include the Model MZ-1, which will have such automatic recording features as track numbering, storage of both time and date of recording, and location of remaining blank disc space for quick recording plus a function for creating custom titles of recorded tracks or discs. It will have 10-key direct access and a two-line, 24-character, backlit LCD to show primary functions as well as disc title and artist name. The MZ-1 will operate from rechargeable battery, a.c., or car battery. With headphones, battery, a.c. adaptor, and other accessories, the unit will cost $749.95.

The Sony MZ-2P playback-only unit will have such features as shuffle play, random programmability, and the LCD panel for disc and track numbers. It will operate from the same power sources as mentioned for the MZ-1 portable recorder and, with the usual accessories, will cost $549.95.

Early next year, the MDX-U1 in-dash car stereo player, with AM/FM tuner and a built-in controller for a Sony Disc Jockey CD changer, will be available at $979.95.

MD-format licensees now include Denon, Hitachi, Kenwood, Matsushita, Mitsubishi, Onkyo, Pioneer, Sanyo, and Yamaha for hardware. For soft ware, some 300 prerecorded MD titles are expected from such labels as Angel, Atlantic, Capitol, Columbia, Denon, dmp, Elektra, EMI, Epic, Sony Classical, Virgin, and Warner Bros.

Cost should be similar to that of a CD, as MDs can be replicated in CD plants, using roughly the same technology. As for blank MDs, Sony's 60- minute MDW-60 is available for $13.99.

The 74-minute MDW-74 will follow in the spring. The battle lines are drawn. Though neither Philips nor Sony is promoting the idea that its system is a replacement for CD, the DCC and MD formats themselves can be viewed as competing digital recording systems. Both have their positive and negative aspects. Initially, DCC would appear to have the better sound quality, approaching that of CD in most respects.

But MD is not far behind, and it has the advantage of a no-wear medium and rapid random access-plus the undeniable portability afforded by ESP.

Many industry seers do not believe that DCC and MD can coexist. My own veiwpoint is that, clever and sophisticated as they are, I would question the formats' viability even in a normal economy. In the midst of a recession, I have strong doubts that either will make a significant impact in the marketplace. Both the DCC and MD introductory models are relatively high priced, and blank tapes and discs are considerably more expensive than the lowly analog cassette. And yes, any one can appreciate the noise-free attributes of both DCC and MD, and the unquestionably low distortion. But are consumers willing to pay for this? After all, recording off the air is hardly high tech. Recording pop tunes on a $2 analog cassette has appeal for many people; will they appreciate the superior sonics of a digital recording of the same program, at close to three or four times the expense? I may be an old mossback, but I do appreciate high tech audio developments that help re produce music ever more realistically.

Still, I feel DCC and MD are merely nifty new techno-toys that will enjoy an initial flurry of sales but then become relatively low-volume products. The CD, as it stands or embellished with Super Bit Mapping or other refinements, is still my choice--and not likely to be superseded until it's replaced by systems that record in solid-state memory, with no moving parts.

In the meantime, we have plenty of audio equipment that can benefit considerably from digital signal processing or new digital circuitry. Meridian and Celestion have pioneered in improving loudspeakers with digital technology, and several companies are working on other ambitious digital applications in speakers, mainly in the areas of crossovers and controlling frequency, phase, and impulse response.

A somewhat controversial development is the application of DSP to loud speaker/room equalization. This is a very tantalizing prospect and has the potential to bedazzle with what seems to be the ideal answer to some problems of the loudspeaker/room interface. There are pitfalls to this, with psychoacoustics playing a prominent role.

If DSP can become sufficiently powerful and cheap, it might help resolve some of the inherent problems. In the video realm, DSP will have a major impact. In the February issue, I reported on the new Dolby SR-D digital format for motion picture sound; more than a dozen theaters are now equipped to show SR-D films, and other theaters will be coming on-line.

More important from a home theater viewpoint is that Dolby Laboratories has developed the AC-3 Adaptive Transform Coding Algorithm, another form of data compression. The SMPTE Surround Standard, now designated the 5.1 surround system, specifies six channels: Left, right, center, left rear, right rear, and 100-Hz sub-bass (i.e., subwoofer). Using Dolby AC-3, the 5.1 system can be encoded at 64 kilobits per second per channel and still pro vide wide-range high-fidelity sound equal to that of AC-2's 192 kilobits per second per channel. The AC-3 system should enable the 5.1 surround signals to be accommodated on a videodisc.

Thus, not only will a new generation of videodiscs provide all the usual benefits of digital sound with respect to high S/N ratio, low distortion, and wide dynamics, but each of the channels in the surround field will be totally discrete! In closing, I offer a plea that unfortunately may fall on deaf ears. Many owners of home theaters have complained that after acquiring the usual library of blockbuster films, they are disappointed with the "surround sound." The music score is in surround, but few motional dynamics re late to the action. These people, and I count myself among them, would like to see videodiscs rated and labeled as "MS" for Music Surround and "AS" for Action Surround. I wish us luck!

(adapted from Audio magazine, Dec. 1992; Bert Whyte)

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