True to their promise, the Philips I UK people have delivered to me a first sample recorder for their new DCC (Digital Compact Cassette) system. In the nature of these things, the recorder itself and the half-dozen pre-recorded cassettes delivered at the same time show signs of hasty preparation and I was warned that all the functions and display modes might not work according to plan. Making due allowances, and wasting a certain amount of time tracing lost Track start IDs and other idiosyncrasies, I was still able to assess the potential of this medium, as patient readers will discover.
There is absolutely no doubt in my mind that the future for home recorders and music playback systems of all kinds is digital rather than analogue. The burning question, not yet answered, is whether that future lies with discs or tapes or both. We have seen Cempact Disc take over the play-only 'market in less than a decade, eclipsing the 45-years-old vinyl disc in the process. Now the industry seems determined to replace the good old analogue tape cassette, which has been around for nearly 30 years as the preferred home recording (and playback) medium, with something digital. Unfortunately, for anyone with my tidy mind and desire for a quiet life, both disc and tape formats have been proposed and scheduled for launch this year.
Of the suggested magnetic tape formats, the DAT (Digital Audio Tape) cassette has so far proved too expensive and unattractive to the record companies as a carrier for prerecorded music, but has sold moderately well to professionals. Now we have the Philips answer, supported by Matsushita in Japan and a growing roster of other hardware and software companies: the DCC system, which carries on some of the features of the analogue cassette but adds the benefits of digital processing. I outlined the principles of DCC in my "DCC Update" article in our February issue and I propose to concentrate here on what it does rather than how it does it.
This first DCC machine, the Philips DCC 900 (£499.00) looks for all the world like a rather chunky cassette deck or CD player, but cheaper minis and portables are to follow soon. It is in the dark grey livery chosen for the current Philips 900 Series of hi-fl separates and has the same projecting bottom strip of controls and large circular 'drum' feet. The cassette compartment glides out like a front-loading CD tray. The cassette is simply laid inside, label upwards, and never needs to be turned over since the system is based on auto-reverse operation.
Commercial pre-recorded DCC cassettes have the CD-type Table of Contents encoded at the start, from which the machine memorizes all the necessary ID timings to provide quick access to any track (musical selection) on either Side A or B. The word "quick" is relative of course, since the tape has to be fast-wound and the tape head switched or flipped as necessary to search out the required track ID: the time this takes will depend on how far away the new track is but will be much longer than we expect from a CD. However, the large display mounted centrally below the cassette drawer offers a whole repertoire of user-friendly text information.
Loading the cassette produces a "Reading Text" display followed by the Album Title. Successive taps on the Text button change the display to Track Title, Artist name, total number of tracks and tape duration. Alternatively, the Time button will similarly cycle through Absolute Time, Track Time, Remaining Time and Counter mode (an old-fashioned four-digit tape position indicator). User-recorded DCC cassettes produce no text displays but will show track numbers and timings, and the usual track skip function allows easy access by recognizing gaps (tape silence, below –60dB) of at least three seconds.
A much-vaunted feature of the DCC system is its ability to play (but not record) conventional analogue cassettes. You load the cassette in the same way, with Side 1 upwards, and have the usual track search/skip facilities, but of course without the helpful text displays. In addition to all the standard controls the DCC 900 has the special controls and rear panel socketry associated with digital recording. There are input sockets for analogue source and digital source, coaxial and optical, as well as output (playback) sockets for the three types of connector, all selectable from the front panel. In fact the analogue output sockets are duplicated to provide a choice between Fixed level and Variable level playback via Volume up/down keys on the remote control handset.
Recording from a digital source, e.g. the digital outlet provided on most up-market CD players, is relatively straightforward, and of course the DCC 900 has the built-in SCMS (Serial Copy Management System) which legalizes home taping of copyright material, whilst inhibiting the digital dubbing of a digital copy—so you can record from CDs with a clear conscience. The musical sound level is simply cloned, as is the sampling frequency incidentally, so there is no need to fiddle with the recording level or even watch the level meter, except as a reassurance that all is well.
If you insert a wholly blank DCC cassette and press the Append key, the deck searches for the beginning of Side A, writes a buffer area (lead in) and Tape Begin marker, and goes into the Rec/Pause mode. This allows you to listen to the source, perhaps to locate a chosen start cue, and displays the signal level. Then simply pressing the Record key sets the recording in motion, with sequential track ID numbers encoded automatically as each new track is detected. Pressing Stop brings the recording to an end and writes a Stop marker. You can enter extra Start markers at any time during recording to provide personalized cue points, or enforce a side change by inserting a Next or Reverse marker, e.g. during Track 5 if you want Track 6 to begin either at the beginning or at the same point on Side 2.
When you load a partially recorded DCC cassette, the same drill is followed but the deck cleverly seeks out the end of the last recording on the tape, and plays the final 10 seconds, before going into the Reel Pause mode. There are slightly different drills for overwriting (erasing as you record) previous recordings or recording from specific locations of your choice. Naturally these operations can play havoc with the Track Number sequence but there is a very helpful Renumber facility which can be used at any time. This scans the whole tape from the beginning, checks the track numbers, changes them as necessary and revises the track listing in the Table of Contents at the beginning of the tape. The deck even displays "Renumber?" if you unload a cassette where renumbering might be advisable.
Recording from an analogue source retains most of these facilities but of course requires correct adjustment of the Recording Level knob, and Balance if necessary. The 16segment twin bargraph meter has a red –12dB marker to which average programme peaks should be set. This should be enough to prevent the loudest peaks from exceeding the OdB level and introducing nasty overload distortion.
Philips's PASC (Precision Adaptive Sub-band Coding) module, which reduces the bit-rate from CD's 1,536 kilobits per second to 384kb/s. The system claims the equivalent of 18-bit encoding, a dynamic range of 105dB and distortion below 0.0025 per cent, which is theoretically better than CD or DAT though this assumes that its rejection of signals below a dynamically varied threshold is indeed inaudible under all conditions.
The remote control unit duplicates all the important functions and in addition provides 0-9 keys for direct track number selection and volume up/down as already mentioned. There is also an ES! Bus connection which provides one-button operation and CD Synchro recording when the DCC 900 is used with other Philips 900 Series units.
Playback of ordinary analogue cassettes needs no special care. The tape type is identified and selected automatically by reference to the slots in the cassette shell, but the user must select Dolby B, C or off. The only tape position display is the four-digit counter. Auto-reverse operates as expected or there is the alternative of a Side A/13 switch if required. Using the Next/Previous buttons will skip to the next section of tape silence and, as we might also expect, go into side-reverse and play Side B if Next is pressed during the last item on Side A.
My operational checks were somewhat frustrated by the unready state of the player and cassettes. For example switching to Dolby C simply muted the output and the cassettes became fairly warm if left in the machine too long. I am told that this latter problem will not occur, as later machines will have the necessary ventilation holes added.
Technical performance, however, was impressive. I began by checking out the playback quality using the mixed bag of pop and classical DCC cassettes supplied. Very soon, repeating the sensations I had experienced with several DAT machines, my ears responded favourably to the wide frequency and dynamic ranges, the absence of background noise, distortion and wow: indeed I could hardly believe that I was listening to a magnetic tape. Philips had thoughtfully sent me their DCC Audio Performance Test cassette containing a selection of test tones and other response-checking signals. This enabled me to test the digital playback performance divorced from recording, and my results lined up pretty well with the maker's specification. Frequency response was flat from 201-lz to 20kHz, signal-to-noise ratio, channel separation and distortion were as claimed.
I have said that the listening tests were impressive, implying that DCC sound quality can be regarded as basically on a par with that of CD, despite the nefarious bit-rate reductions and psychoacoustic' contouring tricks that are necessary to squeeze digital audio signals on to a tape travelling at the regular cassette crawling speed of 4.76cm/s (see my February article). As it happens I had on my shelves the CDs corresponding to some of the DCC cassettes supplied. Synchronizing the start of the Charles Dutoit/Montreal CD and DCC of Bizet's Carmen and L'Arlèsienne Suites on Decca ((1) 417 839-2DH, 6/88), for example, with the levels precisely matched, enabled me to switch between the two sounds which a consumer might expect to hear from the two media. Differences, if there were any, were insignificant and most people would surely be happy with either. As on numerous other DCC demonstrations I have attended over the past year, I was left with a feeling that the acous tic ambience was larger and more open on CD, but only by the merest whisker.
Carrying out measurements on the record/playback performance again produced results which match or come very close to the machine specification. Channel separation exceeded the claimed figure of 85dB at lkHz and was still a full 82dB at 20kHz. Low-level linearity strayed a few decibels compared with the best CD decks but should not seriously degrade the sound quality. Certainly when I recorded from CDs of known high quality sound and balance, via the digital connections, and then compared the DCC dub with the original, any change in quality may be described as very tiny. Recording via the CD player's analogue output and the DCC 900 analogue input did appear to take some life out of the reproduction.
Analogue cassette playback was up to the standards we might expect from a decent mid-price cassette deck, which is to say well below CD quality. My WC calibration cassettes showed some response wobbles, perhaps because the review machine had not been so carefully aligned for analogue in the rush to get the digital performance up to scratch. Careful listening did reveal a constricted treble response, tape hiss of course, narrow stereo stage and less steady pitch. Nevertheless, depending on how well the DCC medium itself becomes established, and the catalogue of pre-recorded music expands in the coming months, I can see that buying a DCC deck like this well endowed example could be a sensible way to upgrade one's cassette system. The analogue recording facility is lost but the move to digital recording should be a vote catcher.