Can a standard audio cassette running with Dolby S really form the basis of an 8-track recorder with a performance to rival open reel models? Dave Lockwood is surprised by the results of his own tests.

When Tascam launched the Dolby S version of the MSR24 one-inch 24-track to so much critical acclaim last year, a Dolby S version of the 238 seemed the obvious next step. After all, the Dolby S system was specifically designed to upgrade the performance of the humble compact cassette to the point where it would continue to be viable compared to the ever-widening range of digital consumer media. The original 238 model seemed to many people something of a technical marvel; the staggered, dual head configuration, and an extremely high quality direct drive transport allowed every last drop of performance potential to be squeezed from the limited track width. Add in dbx noise reduction, and the result was a nominal frequency response extending to a remarkable 16kHz, and a most impressive 90dB signal-to-noise ratio. Furthermore, the transport featured all the control interfaces of the most up-market Tascams of its generation — transport synchroniser and external computer control capability was already there, before most people were ready for it. This was quite obviously a serious machine, even capable of professional usage in, say, certain areas of the music-for-picture field. As a demo recorder it had all the advantages: compact, cheap to run (cassettes are an awful lot cheaper to buy than reels of quarter-inch or half-inch tape), and you couldn't spool off accidentally, no matter how careless you were.

However, the low tape speed (compared to an open-reel system) and narrow track width of the 238 obviously taxed the dbx system to the limit, and I have to admit that, subjectively, the Dolby S version results in an undeniably better sounding, although slightly noisier, machine.

External Adjustment

Externally, there is no change from the original model, apart from the addition of some holes in the top of the casing. These allow access to the internal Bias and Level calibration (line-up) presets, without having to dismantle the machine. Although Dolby S seems far more forgiving of machine response errors than, say Dolby A, accurate line-up is obviously a requirement for optimum performance of any NR system, hence the addition of the more convenient external adjustment facilities.

For those unfamiliar with the 238, the 8-track cassette transport is housed in a sturdy, well-built 3U rack-mount casing, finished predominantly in a sober matt black. To the rear are the fixed mains lead for the integral PSU, and 16 phono connectors for audio line ins and line outs at the nominal -10dBV interface level. A socket for the dedicated remote control unit (RC88), a footswitch drop-in jack, and the 'Accessory 2' serial interface complete the rear panel facilities.

With the cassette compartment to the left, eight 12-segment green/red LED bargraph meters occupy the whole of the right-hand side of the front panel. These have an easy to follow, fast, peak reading, peak hold characteristic. Beneath them, the track ready switches have confirmatory status LEDs, which is just as well, as the switches themselves are a little low on tactile feedback, with a very short throw.

Head Configuration

The cassette compartment door cover can be removed to give excellent access to the heads and tape path for the cleaning and demagnetising essential for optimum performance. Examination also reveals a good solid, cast base plate (no flimsy pressed or bent metal components here!). The unusual head configuration can also be clearly seen, with (moving from left to right) the erase head away on its own to the left, and then the adjacent pair of record/replay heads, with the first handling tracks 5, 6, 7, and 8, and the second tracks 1, 2, 3, and 4, interleaved between them, so that nominally adjacent tracks such as 1 and 2 are, in fact, separated by a track on the other head, in this case track 5. It is as well to bear this layout in mind when track bouncing, for whilst adjacent track bouncing is possible on the 238, with care, best 'bounce' results are obtained by bouncing from one head to the other, ensuring minimum risk of magnetic feedback (the very reason why the staggered configuration was developed).

Another surprising feature of the original 238 was the sophistication of the transport controls, and naturally these remain unchanged in the 238S. The standard line-up of soft touch controls (Rew, F.Fwd, Stop, Play, Pause, Rec) for the electronically governed direct drive transport are augmented by a two-point autolocate, 'Memo 1' and 'Memo 2', which can enter tape locations on the fly. These can then be directly located to via 'Loc 1' and 'Loc 2' buttons, which are independent of the present transport status. 'Repeat 1-2' automatically cycles between the two memorised points, to allow repeated rehearsal, without the hassle of having to constantly operate the transport. A useful 'Check' mode allows the memorised values to be interrogated via the display, without having to actually relocate the tape. The independent return-to-zero completes the impressive line-up of memory facilities.

Auto Drop-In

The programmable drop in facility is as easy to use as the memory system; after selecting 'Punch In/Out Rehearsal' mode, you simply execute your drop in (and out) at the relevant points. You are prevented from actually entering record whilst in Rehearsal mode, so you are quite safe even if you mess it up. About three seconds after the 'out' point, the transport automatically rewinds, and cues itself up at a sensible pre-roll distance before the 'in' point. You can then 'audition' the auto-drop by pressing Play; at the relevant points the monitoring will flip from tape to input, thus simulating the drop in. Should it prove unsatisfactory, you can activate 'Clear', and start again, but if all is well, you can enter 'Auto In/Out' mode, and the drop will be executed for real, using the programmed locations. In practice, the monitoring takes a little longer to flip over on the actual record pass than it does in rehearsal, so it sometimes sounds as if you have clipped the start of the following part, when in fact all is well when you play it back. You soon learn to make allowance for this. In general, allowing for the limitations of a slow linear tape speed (relative to a high speed, open reel transport), the drop in performance of this machine is very good, entering and exiting record status without introducing any audible side effects, provided you are not attempting the impossible, ie. punching in on the middle of a note!

"Whilst adjacent track bouncing is possible on the 238, with care, best 'bounce' results are obtained by bouncing from one head to the other."

The autolocate memories, and therefore the auto-drop system, do not, of course, have the benefit of a timecode track to work from, and are therefore dependent on the tach pulses used to drive the counter. Naturally, this is subject to a certain amount of inaccuracy due to tape slippage. I tested the same drop in point about a dozen times and found it remained remarkably consistent, but over the course of a whole session, with some three or four hours on the same song, with all the shuttling and rewinding that that inevitably entails, zero had drifted quite significantly. This is no surprise, however, for many a 'pro' machine is the same. Interestingly, you can reset zero on the 238 without losing the actual memory locations; these are recalculated to represent the same points on the tape.

Shuttle

The remaining transport facilities are the +/-12% varispeed control (speed control can be set to Vari, Fix, or External for use with a synchroniser such as a Tascam MIDIizer, or ATS500), and the Shuttle control. Entering Shuttle mode allows you to manipulate the transport via the Shuttle pot just as if you were rocking the reels of an open-reel machine. This is normally only done when editing, and splice editing is one thing that you certainly can't do on a 238!

I would imagine that it is intended to allow you to accurately locate the tape for clean starts; indeed the 238 transport picks up remarkably smoothly and quickly. I was sufficiently impressed with this aspect of the machine's performance to attempt to use it for 'flying in' some backing vocals (I had five simultaneous tracks to fly in, which would normally take three passes with a stereo, open reel machine). Even in the age of stereo sampling, so many of us still find flying in more convenient, especially if you can do it multitrack!

The Dolby S Factor

A few words about the inner workings of the Dolby S system might not go amiss here, as that represents the sole difference between the review model and the original version of this machine. You might well be wondering, at the moment, why Tascam would bother to go to all the trouble of releasing a rival to their own design!

Although Dolby S has been widely spoken of as the 'consumer version' of the professional Dolby SR system, it should perhaps more accurately be viewed as a further development of Dolby C, with an additional LF band, and a couple of the more sophisticated functions of SR thrown in. Although originally developed specifically to improve the performance of domestic cassette machines, the system, at present, has undoubtedly achieved greater prominence in the semi-pro recording field, via its excellent performance on one-inch 24-tracks and half-inch 16-tracks. However, the terms of the licensing agreement for Dolby S actually prohibit manufacturers from using the system on equipment deemed to be 'professional'. A more thorough description of the Dolby S principle may be found elsewhere in this issue.

The Acid Test

If you are a cassette 4-track owner, and you haven't actually heard one of these, you could be forgiven for thinking that eight tracks on cassette, notwithstanding Dolby S, must inevitably sound somewhat inferior to your machine. Well, forget any cassette multitrack you have heard before; the combination of a very superior cassette transport and innovative head design and electronics results in something that sounds much closer to open reel than cassette. A/B comparison against a one-inch 24-track was really quite alarming; you have to choose the source specifically to reveal the differences, which amount primarily to an inevitable curtailment at high frequencies, and a certain lack of real body to the sound at very low frequencies. Bass drum retains all its 'thwack' in the midrange, but loses a little of the weight that gives it real power. Cymbals and hi-hat become a little splashy as their real HF sparkle is rolled off; nevertheless, they still contrive to sound clean, provided they are not over-modulated — Dolby S has the Dolby C characteristic of sounding conspicuously clean at HF. However, if you have to go looking for limitations in order to hear them, they can't be that bad. Subjectively, there is no lack of top end on a 238S.

Dolby S does not rival dbx for its absolute degree of noise reduction; a dbx encoded tape, in the absence of signal, will be virtually silent. Nonetheless, an unweighted, 20Hz to 20kHz, signal-to-noise ratio of 64dB — for a single track, with Dolby S switched in — is still most acceptable. It does mean, however, that it is worth taking simple precautions against noise build-up in a whole mix, muting or gating any channels when they are not active and taking care to always record at the optimum level. To be realistic, with most sound sources, the off-tape noise level is not so much a factor of the tape machine or the type of noise reduction system but of the source itself.

It is essential with dbx that you do not overmodulate at the record stage, for tape saturation then compresses the signal still further and makes it impossible for the expander stage to reconstruct the original dynamics. This is one reason why many people complain of unsatisfactory results with dbx. Dolby S, like all the Dolby systems, in fact, applies less processing to the signal as its level rises, and this allows you to push the level on tape quite hard when you want to, without anything undesirable happening. Tape compression effects can be used quite creatively, but on cassette, particularly 8-track cassette, you do have to bear in mind the consequences of crosstalk onto adjacent tracks on replay from anything recorded at a particularly high level. In general, the crosstalk performance of the 238S is more than adequate, and provided you are not asking the impossible of it, you will not be disappointed.

Verdict

So what reasons are there left for choosing open reel in the budget 8-track sector? There is no denying that the advent of the 238S now allows the cassette system to compete more or less on equal terms. In opting for cassette you are compromising merely on the lack of splice editing, which in reality is far more of a drawback in a 2-track mastering system than on a multitrack, and (perhaps more significantly) on the accuracy of the drop in/out (especially out) performance, which is always a great deal faster at higher tape speeds. To set against this are the sheer convenience and portability of this package, the many advanced operating features, and the not inconsiderable saving in tape costs. The 238S is a serious alternative to quarter-inch and even half-inch open reel 8-track.

Just as Dolby SR undoubtedly extended the life of the analogue multitrack in the professional domain, I suspect that Dolby S may ensure that budget, narrow-gauge multitracks will be able to ward off their digital 'usurpers' for a while longer. In the 238S, second generation 8-track cassette will find some serious applications in A/V work, demo studios, and above all, perhaps as one of the neatest and most convenient ways of adding just a few high quality audio tracks to a sophisticated MIDI system (the 238's interfaceability, allowing software control, will be particularly welcome here).

The 8-track cassette is obviously here to stay, and with Tascam's usual impeccable attention to detail, and high quality finish and manufacture, the format couldn't have a better advertisement than the 238S. Thoroughly recommended.

Further Information
Tascam 238S £1,499 including VAT.

TEAC UK Ltd, (Contact Details).