As an alternative mastering format, DAT is now a fact of life and, for better or for worse, seems likely to remain so for the forseeable future. Perhaps only the development of genuinely commercially viable, erasable optical disk systems will challenge its unique position as a digital system embraced by consumer and professional alike. To see the 'pro' audio industry so readily accepting such an essentially 'domestic' format has left at least this observer more than a little surprised.

During the early development stages of Sony's PCM F1 (perhaps the first digital unit to cross the pro/consumer boundary), one was prepared to accept the many quirks and failings of the system, simply for the benefits of 16-bit digital sound at an affordable price — the video transports were inherently complex and unreliable, you were obliged to work to the -10dBV standard, and you couldn't edit (in fact, you couldn't even start or stop with any degree of precision, or without putting an audible glitch oh tape).

If it had been suggested then that the next significant development would be to miniaturise the helical scan rotary-head system, reducing the tape cassette itself to the size of a matchbox, and using an effective track width of less than the thickness of a human hair, I think everybody would have found the idea laughable. In some ways, I am not so sure that we still shouldn't!

And yet, of course, it works, and very well in most cases. DAT is significantly superior to F1 in a number of ways that reflect the technological advances made in the intervening years, particularly both in terms of operational convenience and data handling.

PRO DAT

Although many first generation DAT machines may have had fairly obvious 'domestic' status, being denied 44.1kHz sampling, we are now seeing an ever increasing number of models potentially qualifying for the accolade of 'pro' status. The latest of these, the DA30 from Tascam, is typical of the breed, in offering switchable 44.1/48kHz Sampling rate (32kHz from a digital source), oversampling D/A conversion, a choice of digital interfacing, and balanced +4dB operating level for the analogue in/out circuitry.

However, the DA30 does not offer a timecode track facility, nor does it offer a four-head digital off-tape monitoring system, which surely must eventually become the standard setup for the 'pro' DAT machines of the future.

CONSTRUCTION

The DA30's 3U rack-mount casing has an all black fascia, relieved only by three large silver control knobs. The unit is neither excessively deep, nor abnormally heavy, in comparison with other rackmounted DAT machines. An entirely conventional looking set of transport controls are placed to the left of the fascia, beneath the tape drawer. 'Skip', 'Standby', and 'Rec Mute' are the only controls that might not be immediately obvious in function — Skip forward or reverse are the simplest of the automatic location facilities, enabling the start of the next or previous track to be located automatically. Multiple presses facilitate skipping any number of tracks in either direction, with Skip functions being available from any mode. Standby does not refer to power status, but to a function that causes the DA30 to go into Pause mode, rather than Play, after an autolocate function. Record Mute writes a four-second 'silence gap' to tape, activated either from Record/Pause, or normal recording mode.

There are effectively two input monitor modes. Record Ready, accessed through Record/Pause, activates the head drum, setting up the machine for a near instant start, and giving input monitoring, presumably through the convertors. Normal input monitor, activated just via Record, from Stop, gives line in signals at the outputs, without the head drum contacting the tape. The DA30 is programmed to automatically drop out of Record/Pause mode after a rather generous eight minutes, as a means of protecting against unnecessary head/tape wear. Curiously, it is not possible to activate normal input monitor from the supplied remote control unit in exactly the same way as on the machine itself (just by pressing Record) — you are obliged to press Stop and Record together. I suppose this is of no operational significance whatsoever, but it does seem strange nonetheless.

The DA30 uses individual input level controls for the two channels. Unusually, the large knurled control knobs are mechanically interlocked for easy stereo operation. If you want to override the interlock, you can do so easily by holding one knob whilst turning the other. Output levels are set from a single stereo control.

CONNECTIONS

The DA30's rear panel is populated by a mixture of phonos and XLRs, plus remote control connectors. The supplied remote, perhaps surprisingly, is not an infra-red unit but connects via 15 feet of cable. Whilst this may seem somewhat less convenient than a cordless system, it has its compensations both in inherent reliability and the fact that you don't have to point the remote at the deck in order to use it. The remote is an essential part of the system, for not all of its functions are duplicated on the front panel of the DA30 itself.

A 15-pin D-sub connector is also provided for customising the external control options using simple contact closure switching. The basic transport functions, plus some sub-code routines, can be placed under the control of external devices, such as fader-start switches or event controller relays. Some pins are used to output voltages for status indication.

Analogue audio connection, in and out, is via standard electronically balanced 3-pin XLRs at +4dBm (1.23V). Alternatively, phonos (RCA jacks) are provided for unbalanced connection at -10dBV (0.316V). There are actually two sets of phono outputs, one with output level variable from the front panel control, and the other fixed. The XLRs follow the level control, with a maximum output level of +22dBm.

There are two digital connections available, providing both AES/EBU and SPDIF (Sony/Philips Digital Interface Format) facilities. Balanced XLRs are provided for AES/EBU (one in and one out, of course, as the two channels' information is interleaved), the termination conforming to the agreed professional digital protocol (CP340 Type 1). Gold-plated phonos are provided for the 'consumer' 75 Ohm coaxial digital interface. Data format conforms to the CP340 Type 2 EIAJ protocol, and is described as "largely compatible with the SPDIF format".

The only connection made via the front panel is the stereo headphone socket. This has its own volume control, giving plenty of clean level into 600 Ohm headphones, and will also handle low impedance types.

DISPLAY WINDOW

The DA30 employs a single large information window to display levels, counter, and anything else worth knowing about the process currently taking place. The orange-on-black display is very bright, and can be read from further away than most other displays. In fact, there is a neat little facility on the remote for setting the display brightness to one of four different levels.

The fine resolution multi-segment audio level meters operate in conjunction with the Margin facility. This is a digital peak-hold meter indicating the remaining headroom before the digital saturation point is reached. Like all digital systems, there is no margin for error as digital distortion crunches as soon as you run out of bits — there is no equivalent of the analogue quality of gently sliding into tape saturation, which can actually be quite useful on some material. Like F1, I found that the system is actually reasonably forgiving of a very short-term overload, but even this is better avoided.

Margin displays the highest reading since Margin Reset was last pressed, facilitating easy level optimisation. Maximum modulation would result in a 0dB Margin display, but if the zero is flashing, it indicates that the meter overload point was reached, and that the recording is potentially distorted. I say only potentially, as I think the Tascam system 'plays safe' just a little, for I encountered some warning flashes on recordings that subsequently proved perfectly 'clean' to my ears. Nevertheless, I would be inclined to stick within the advised limits for serious work.

Unlike analogue tape, digital dynamic range is not frequency dependent at all, and you can no more 'get away with' anything at low frequencies than you can at the top end of the spectrum.

The DA30's counter facilities are governed by the Counter Mode switch, which toggles around the following options: Absolute Time (position on the tape with respect to the start), Program Time (position within the track), Remaining Time (time to end of tape), or normal counter mode (distance from the last reset zero).

A comprehensive range of the usual Skip/Search sub-code index functions are provided, as expected. Start IDs and Program numbers can be assigned automatically, in Auto ID mode, or inserted manually. Position Mode allows these to be placed with great precision to within an accuracy of five frames, which represents 150ms of audio, up to a limit of one second in either direction.

Position does not work by moving existing IDs — you must first erase a wrongly positioned ID, and replace it using the Position facility. Removing a Start ID, via Erase ID, also deletes the Program number pertaining to that piece, which will leave the Program numbers on the tape out of sequence. The usual Renumber operation can be carried out to restore the sequence whenever Start IDs have been deleted or inserted. Skip IDs, allowing the automatic omission of defined sections (unwanted mixes, incomplete takes, etc), can be written or erased with the same ease as Start IDs.

The usual automatic location functions are present. These include searching for a specific Program number, and End Search, which finds the end of the 'formatted', or previously used, sector of the tape. A number of Repeat Play options are available, allowing individual tracks, the whole tape, or a preprogrammed sequence of Programs to be replayed repeatedly, up to a maximum of 16 times. Up to 50 Programs can be used in a sequence, with a simple entry procedure, but editing the sequence is not so convenient — you have to re-enter all entries programmed to follow the one you want to change!

"The sub-coding offers considerable operational convenience, and the machinery seems altogether robust and reliable."

REMOTE CONTROL

The RC30D remote control unit duplicates all the transport functions and adds a numeric keypad and several buttons dedicated to additional programming functions, such as the Repeat Play, Skip Play, and Sequence Play facilities. Unusually, these extra facilities are accessible only via the remote, with no duplication of their controls on the front panel of the DA30 itself.

The numeric keypad is used for direct entry of Program numbers, or Step numbers, for pre-programmed sequence playing. Clear is used to cancel number displays, relating to any status, which have been entered from the keypad. Stop M is an additional location aid which establishes a temporary memorised location in either Record or Play. Subsequent fast winding in either direction will stop at that point. A second press of Stop M cancels that location.

Skip Play mode, which causes the machine to automatically wind on to the next Start ID upon encountering a Skip ID, is also accessed solely by means of the remote. Intro Check causes the tape to play the first 10 seconds of every piece with a Start ID throughout the tape. Pressing Play during one of the intros will cancel Intro Check and enter normal Play mode.

Finally, there are Forward and Reverse Search buttons which give monitoring at nine times normal speed for as long as the switches are held. The audio signal is naturally heavily glitched at this speed, but it is still perfectly adequate for establishing where you are on the tape, when you are between ID points. This differs slightly from pressing Rewind or Fast Forward whilst in Play, which, like the equivalent facility on many CD players, outputs similarly glitched audio, but at about three times normal speed for more precise cueing.

THE SUBJECTIVE TEST

The DA30, as any 16-bit, 44.1 kHz sampling unit should, sounds very much like the input signal. Provided you do not clip it, or seriously under-record, it sounds as clean and accurate as you could reasonably ask for.

Comparison (highly subjective and unscientific comparison, I freely admit) with a Sony PCM F1 and a Casio DA2 showed the DA30 to be marginally preferable to both. This conclusion was unsurprising to all involved, bearing in mind the developments in coding and error-correction since the design of the venerable old F1, and the Casio unit's slightly compromised data format.

Comparison with analogue tape (1/4", 15ips with noise reduction) shows just why DAT has such a strong appeal to the middle ground of the audio market — no contest really (unless you happened to be specifically seeking a bit of typical analogue bottom-end lift).

Comparison with a 1/2" analogue machine at 30ips with no noise reduction was not possible during my comparatively brief acquaintance with the DA30, but from the results of a similar comparison between 1/2" and F1, I would extrapolate only the following: of the two, the digital format undoubtedly sounds the more like the input signal, but what changes there are to the sound from the 1/2" analogue machine are not always necessarily inherently undesirable, depending on the programme content — sometimes the bass is a little warmer, sometimes a bit of 'squash' makes the top-end sound a bit harder. However, DAT is demonstrably the more operationally convenient format (apart from the lack of a varispeed function), and has only one major drawback — the lack of an editing facility.

Razor-blade editing used to be one of the fundamental skills of the audio industry, now you find engineers in studios who have never had to do any at all! Like video editing, DAT editing will require two machines, with a specific editing interface and some sort of dedicated controller. Until that is widely available, DAT will remain a non-editable medium.

You can, however, make compilation copies with reasonable precision. Anyone who has struggled for years with the instability of startup on an F1 (to say nothing of the counter that displays time to the nearest 10 seconds!) would welcome the performance of the Tascam DA30 in this area. I generated not a single click or glitch during a simulated assembly-copy session. Startup speed was impressive at under one second, and the entire operation seems altogether predictable and consistent.

ERROR-CORRECTION

The weakest link in any DAT system is undoubtedly the tape itself. The narrow track width must place immense demands on the error-correction system, particularly as machines begin to age and their ultra-precise mechanisms start to drift out of alignment — DAT machines are not readily user-maintainable. Tape errors may not be audible as a full glitch, but ever-increasing amounts of interpolation may be taking place at a level which degrades the sound, imperceptibly at first, and then perhaps more seriously. Regular 'cloning' via digital copying is probably the only way to ensure the long-term safety of valuable material.

I am already aware of degradation in the performance of some of my older Sony F1 masters, and whilst DAT error-correction and concealment is superior and, I would think, the system is unlikely to be subject to random, replay-only, 'phantom' glitches to the same extent, there must be cause for some concern at the headlong rush to accept the new format.

Notable by its absence on the DA30 is any form of error-correction rate display. This would perhaps enable the operator to be aware of the point when either the tape or machine performance begins to seriously degrade, and to therefore take the necessary action. Surely this should be standard equipment on any machine wishing to call itself a 'Pro' DAT?

IN CONCLUSION

Tascam's DA30 is an impressive machine which goes some way to answering the charge, voiced in certain sectors of the industry, that 'Pro' DAT will just be consumer DAT with a higher operating level and a price tag to match.

The DA30 certainly has the 'feel' of a professional recorder. It has large, clear switches and displays, rather than the function-laden look of the more consumer-oriented models, with most of its peripheral functions 'hidden' on the remote. The sub-coding offers considerable operational convenience, and the machinery seems altogether robust and reliable. This is a recorder that I would be happy to take on a location recording session — it would certainly be a lot easier than carrying two Betamax video machines around (F1 owners always use two videos, not because one of them is guaranteed to break down before the end of the session, although that may also be true, but to guard against the system's highly destructive random tape errors by running two recorders in parallel).

Apart from the lack of an error-rate display, any criticisms I might have relate to the DAT format in general, rather than to the DA30. Just because you can make something small, does not necessarily make it a good idea to do so. The tiny 2000 rpm DAT head drum has less inertia than a bigger one would have had, a wider tape/track width would allow for more data redundancy, and the DAT tape and box are just too small to carry all the written information usually found on an important master.

More positively, DAT undoubtedly gives access to a level of performance not previously approachable at this sort of price and, irrespective of any longer-term reservations, is now well established as a format for audio mastering, archiving, cartridge machine emulation and other broadcast usage, as well as being particularly suited (by its long recording time) to live performance recording. Interchange of tapes between machines without having to worry about azimuth, correct line-up, EQ, and noise reduction is certainly welcome, and whilst some reservations are in fact beginning to emerge regarding interchangability, I believe these primarily concern some of the less standard, 'budget' machines on the market.

In conclusion, Tascam's DA30 provides a significant number of professional features, such as 44.1 kHz sampling as standard, 8x oversampling D/A, AES/EBU digital interfacing, and balanced +4dBm audio connection, all at the affordable price of £1356. If you don't need timecode, and you want a 'professional' DAT recorder, then the DA30 has got to be considered a frontrunner among the contenders.

FURTHER INFORMATION

£1356 inc VAT.

Teac UK Ltd, (Contact Details).