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Tascam MSR16S Multitrack

Having made its debut on the new generation of affordable 1" 24-tracks, Dolby S has now given a new lease of life to Tascam's MSR16S. Dave Lockwood explains why.



After the success of Tascam's first Dolby S-equipped machine, the MSR24S, it seemed only a matter of time before we would see other models in their range upgraded to take advantage of the remarkable qualities of the new standard in semi-pro noise reduction. So it has proved; the MSR16 1/2" 16-track is now available as the MSR16S.

Although identical in every other way to the original model, Dolby S will give it a significant performance advantage over a Dolby C-based machine (Fostex have already announced the G16S), and will certainly give a new lease of life to a product that, I felt, failed to achieve its deserved market position. This shortfall was, however, probably due in part to the deflection of interest caused by the subsequent announcement of the MSR24.

CONSTRUCTION



The MSR16S is a very attractive, compact machine, beautifully constructed, and finished predominantly in black and grey. Heavy-duty rack ears form an integral part of the substantial chassis side-panels. In comparison with many semi-pro recorders, it is built like a tank, and weighs considerably more than you expect for its size. Put simply, it has the feel of a recorder built to withstand the rigours (and abuse) of serious professional usage, day after day, without premature breakdown. The usual pressure tests around the headblock produced noticeably less effect than normal — this is a solid piece of engineering that should remain stable over an extended period.

The symmetrical transport uses a standard pinch-wheel/capstan assembly, with wide diameter roller bearings on all the major elements in the tape path, brushless DC reel motors, and phase-locked loop capstan drive. The large roller at the right-hand end of the headblock is the source of tach information for the real-time counter, employing a slightly ribbed contact surface for optimum adhesion. The tape tension arms are mechanically damped against excessive vertical pull, rounding off a transport that certainly inspires confidence.

Full logic, motion-sensing transport control is provided, resulting in optimal transition between modes, with the least possible strain on both tape and system. For a narrow-gauge, semi-pro format recorder, the G16S's tape handling really is excellent.

Below the head block (which is fitted with a retractable shield for the record/sync head), are the LED column meters, track-ready switching, and all other controls, with the large main transport buttons conveniently located at the bottom on the right. Although this whole section of the machine looks as if it is detachable (like recent Fostex models), in fact it only swings down to give access to the line-up presets behind it. (The channel amplifiers are actually on individual plug-in PCBs; great for maintenance. An extender card is even supplied.) Lining-up will, of course, be a 2-stage 'adjust-then-view' process, for the MSR16S, like most semi-pro machines these days, is only a two-head design (with just an Erase and a Record head; the latter also has to handle Sync and Repro).

On the rear panel there are connectors for AC input to the internal PSU (standard IEC thankfully, therefore no annoying fixed mains lead), and a 1/4" jack for the footswitch drop-in facility. All audio connection however, is via phonos, with signals therefore unbalanced, and at the -10dBV 'Tascam/Fostex operating level'. The remaining connectors are all concerned with synchronisation and external control, covering standard SMPTE/EBU, RS232, and a port for the dedicated wired remote (RC-416). A neat little 4-pole DIP-switch is also included, for setting the baud rate (speed of data transfer) of the serial interface.

Synchronisation to an external transport controller is possible via the External setting on the varispeed function; Fix and Variable are the other options. Varispeed read-out is available by means of the Display switch, which toggles the main counter display between 'real time' tape position, or varispeed percentage (this is nominally variable +/-15%, but the actual range is slightly wider). The red fluorescent numeric display, in my opinion, is simply not large enough, and in average lighting conditions, not really bright enough either. There is sufficient panel space for it to have been twice as big, to some operational advantage.

The accuracy of the tape counter, on which the automatic transport functions such as auto-drop are dependent, was very good for a non timecode-based system. Neither prolonged cycling nor long-distance winds produced excessive counter drift. Much is sometimes made of the unsuitability of a tach pulse-based counter for driving an auto-drop circuit, on the grounds that it cannot guarantee an absolutely fixed relationship between the tape and counter — ie. the counter may not always give an accurate reading of where the tape really is. In the most extreme instance, this could allow the machine to drop in at the wrong point.

In practice, you tend to set up the Rehearse function, listen to the in and out points, practise the part a couple of times, and then execute the Auto In/Out function to perform the actual drop. There simply isn't sufficient time or distance involved for the counter to go significantly adrift, unless you were to shuttle endlessly round the same part — but even then you would hear if it moved significantly. For normal music recording applications, the counter-based functions of the MSR16S can be relied upon more than most.

The drop-in performance of the MSR16S, whether in automatic or manual mode, makes it a delight to use. Timing circuitry is employed to eliminate the 'gap' that normally results when dropping out due to the distance between the erase and sync heads; a small section of tape will already have passed over the erase head before you hear the point at which you want to drop out. (Conversely, when dropping in, a small amount of 'overlap' is sometimes generated, ruining many an otherwise successful drop-in.) You still can't do the impossible and get in or out in the middle of a note (this is not digital crossfading after all!), but by staggering the timing of the switching on and off of the heads under microprocessor control, the MSR16S is able to perform conventional drop-ins to a very high standard indeed.

TRANSPORT FUNCTIONS



The MSR16S's on-board autolocate offers two instantly accessible memorised Locate points, and zero return. Auto-play is available (the machine will enter Play once it has located a point), and cycling between the two locate points is easily set up via the dedicated Repeat 1-2 key. Check and Clear functions allow the contents of the memories to be examined or reset.

Several Edit modes are available; the normal Edit mode disables the reel brakes and retracts the tape lifters so you can hear the signal as you move the tape manually across the head (by turning either of the hubs). You don't have to balance the tension between the two reels yourself; the motors do it for you automatically. Entering Edit with the tension arms in the down position (the right-hand arm carries the switch which disables the capstan motor) allows monitoring of tape being pulled across the head by hand, for ditching an unwanted section. Simultaneously selecting Edit and Play enters Dump mode, for performing the same job on longer sections of tape — the transport operates but the take-up reel remains static.

Edit can also be used as a 'cue' facility; pressing Edit during a fast wind operation retracts the tape lifters allowing a suitably HF-attenuated signal to be monitored at high-speed.

Spot Erase, for very localised cleaning-up jobs, is made easier by the facility to enter Record whilst in normal Edit mode — if the relevant track is pre-selected to Ready, you can enter and leave record whilst moving the reels slowly by hand (however, if you exit record when the tape is not moving fast enough, it may generate a click). This works very well, with a bit of practice, but with such a good drop-in performance and with the provision of the auto-drop circuitry, I actually find it quicker and more certain (it is always possible to misinterpret precisely where you are in a track when monitoring at very low speed) to use these facilities in preference to spot erase.

Finally, there is the Load facility, which allows you to create a 'marker' beyond which the machine will not wind, wherever you may subsequently set your zero, thus preventing accidental winding-off. There is also a Spool function, which permits limited-speed winding to ensure a neat tape pack for storage.

All in all, a comprehensive and very practical set of transport functions, of the sort we would at one time have associated only with fully professional machines.

MONITOR MODES



There are three monitor modes, designated All Input, Auto Input, and Insert. All Input is self-explanatory, whilst Insert sets up the normal overdub situation with monitoring following the track status, giving sync output until the machine enters record, whereupon it switches over to input.

It is good to see Auto Input included on a semi-pro machine; this gives input monitoring at all times other than when the transport is actually in Play mode. Effectively, it means that when recording or overdubbing (monitoring via the tape return path), you can maintain a dialogue with the performance area during all wind and stop modes, without the need for constant switching on the part of the operator.

Tracks are selected to Record via switches beneath their appropriate LED column meters; a status LED located just above each one flashes to indicate Ready mode, and remains on when you actually start recording. Metering is via 12-segment green/red LED bargraphs, calibrated to +8dB at the top of the scale with a PPM (fast rise/slow decay) characteristic. The MSR16S seems quite happy to be driven hard, with short-term peaking to full scale producing no discernible ill-effects. Whilst a little more conservatism might have been advisable with the dbx-based model, Dolby S works progressively less on signals as they get louder, reducing the potential for unwanted NR side-effects due to tape non-linearity at high levels.

The Dolby S circuitry, like the dbx of the original model, can be switched out in banks of 8 tracks, or on track 16 only for timecode use. Use of the Sync Lock function subsequently prevents accidental recording on track 16 — a very welcome facility.

IN USE



The question that most intrigued me was how well would Dolby S stand up to the extra demands made upon it by the narrower track width of the MSR16S relative to the MSR24S, which sounds truly excellent. In practice the system was no more taxed by 1/2" 16-track than by 1" 24-track — the MSR16S is basically a very clean and quiet recorder indeed, even before the Dolby S gets to work on it. The principal compromise of the narrower format, as you might expect, actually proves to be neither noise nor frequency response, but crosstalk.

With all 16 tracks recorded, with no input, a residual level of tape noise is evident, but with a spectral content discernibly shifted away from the subjectively more intrusive upper-middle and HF ranges — a dbx machine under the same circumstances would display effectively no noise at all until the signal started. However, a particular quality of the Dolby S system is that the noise level under quiescent conditions does not alter in the presence of signal, allowing masking to take its full effect without modulation of the noise floor to detract from it.

In spite of the relatively narrow track width, the MSR16S has a particularly clean, sweet top end (something the Dolby C-based machines could also lay claim to), and acoustic sources are handled with great delicacy and clarity. Where it loses out relative to a Dolby S 1" 24-track is in terms of the sheer weight available at the bottom end. This is not a criticism (indeed I would have been very surprised had this not been evident), but a simple function of the immutable laws of magnetic tape recording. A more valid comparison of this particular quality would be between three 1/2" 16-track recorders, using dbx, Dolby S, and Dolby C. Although such a side-by-side test wasn't possible, my experience of all three types of machine has them about equal in this area.

The inherent crosstalk level is subjectively as well controlled by Dolby S as it was by dbx, and it was never a problem of any practical significance during 'realistic' testing. Bouncing between adjacent tracks is possible at moderate levels, but is still better avoided — this shouldn't be a problem with 16 tracks to play with.

I performed the same blind listening test as I used on the MSR24S, with a CD running in parallel with its recording on a couple of MSR16S tracks. This time my informal listening panel were consistently correct in their identifications. The difference in sound was generally held to consist of a slight spectral shift at the bottom end (more 100Hz and less 40Hz perhaps?) and an inevitable small loss of transparency, although the performance was felt to be remarkable in view of the narrow track width involved and the fact that the source was the wide-band, complex signal provided by a 'mixed' programme. It may not sound identical to the input, but such alteration as there is will not be seriously detrimental to any particular type of source, especially in normal multitrack usage.

As on the MSR24S, transient performance is particularly impressive, and easily passes all the usual tests designed to catch out noise reduction systems. The half-speed option, which naturally compromises performance both in terms of noise and frequency response, was felt to be significantly more listenable than on the dbx-based version (there is some sense to this, considering how the two NR systems work) and the feature begins to look now like quite a shrewd inclusion.

Dolby S was always intended to be to some extent downwardly compatible with both Dolby B and C (it is also quite respectable when replayed un-decoded, with some obvious HF lift, but nothing in the way of excessive modulation to make it unlistenable). In the domestic market, cassettes encoded with Dolby S are intended to sound OK when played on machines with either B or C (but not vice-versa of course), and some noise reduction will even take place. Tapes originated on an MSR16S should in theory therefore be playable on a Dolby C-based B/E/G16, at least enough to get you out of trouble in the event of a breakdown.

CONCLUSION



16 tracks on 1/2" tape seems to have emerged as the de facto standard for semi-pro/domestic multitrack, simply through the sheer number of machines sold. For so long Fostex had this sector entirely to themselves, and when Tascam's eventual reply didn't exactly take the market by storm, it looked as if that was how things were destined to remain. The MSR16S may change that.

As a result of the rapturous reception given to the Dolby S-based 1" machines, attention has been focussed once again on the pivotal role of noise reduction in narrow-gauge multitracks. Fostex have had to follow with a Dolby S-based G16S (and an external Dolby C unit for continued compatibility with existing tapes, cleverly removing a primary disincentive for upgrading), at last giving format compatibility between Tascam and Fostex in this market. Users can now choose between models on the basis of factors other than a preference for a particular NR system; such as the sophistication of the control features, perhaps.

The MSR16S is, in many ways, a professional recorder sold at a 'domestic' price — only the track format stops it from being regarded as a pro machine. A high quality transport and head design, combined with the unique properties of Dolby S, extract the last drop of performance available from this track width. Half-inch 16-track doesn't come any better than this.

FURTHER INFORMATION

£5016 Inc VAT.

TEAC UK, (Contact Details).

MSR16S SPECIFICATIONS

Machine Format: 16-track, 1/2"
Head Configuration: 2 head system. Erase + Record/Play
Record Reference Fluxivity: 250nWb/m
Bias/Erase Frequency: 145kHz
Frequency Response (15ips) ref 0VU: 40Hz to 20kHz (+/-3dB)
(7 1/2ips) ref -10VU: 40Hz to 16kHz (+/-3dB)
S/N Ratio (A Wtd) (15ips): (with Dolby S) 92dB
(with no noise reduction) 68dB
(7 1/2ips): (with Dolby S) 90dB
(with no noise reduction) 65dB
Distortion: (@1 kHz — both speeds) <0.8%
Adjacent Chan, x/talk: Better than -70dB (NR On) (1kHz/0VU)
Record Amp Headroom: >28dB (1kHz/0VU)
Wow & Flutter (DIN Wtd) (15ips): +/-0.06% peak
(7 1/2ips): +/-0.08% peak
Impedances: Line In: 50kOhms, -10dBV, Unbalanced
Line Out: 220 Ohms, -10dBV, Unbalanced
Weight: 33kg


DOLBY S

Dolby S, although inevitably slightly less sophisticated than its illustrious counterpart, shares the professional Dolby SR system's unique ability to make optimal use of the characteristics of the human ear, whilst simultaneously conforming to the over-riding Dolby principle of "the least treatment is the best treatment" — if the ear cannot hear noise in a particular part of the spectrum, then any signal in that zone need not be processed.

High level signals remain virtually untreated, ensuring that the modulation effects and potentially compromised transient performance of simple broadband compander systems are avoided.

Dolby S consists essentially of five active elements, which can be sub-divided into high and low frequency stages, with a single fixed band operating at LF below 200Hz. The other four elements all operate from 400Hz upwards, with both fixed and sliding bands being simultaneously employed. Two 12dB companders, operating in series, with staggered thresholds, are used to form separate high and low level stages at HF. The fixed and sliding bands interact via a technique called Action Substitution which seeks to take advantage of the beneficial characteristics of both types, without suffering the disadvantages of either. Like Dolby SR, Dolby S produces a noise floor that is not only very low, but which is subjectively not apparently modulated by signal level or spectral content.

Other techniques, such as Spectral Skewing and Modulation Control, seek to mitigate the effects of tape saturation at the frequency extremes, and other potential problems such as transient overshoot in the compressor stages. The remarkable absence of discernible side effects attributable to NR operation demonstrates the practical effectiveness of these measures.

Like Dolby SR, it works; indeed it works wonderfully well. Dolby S is not just noise reduction, but a whole range of signal conditioning processes designed to overcome many of the inherent limitations of recording and recovering signals via magnetic tape. When you know exactly what is going on, you are almost left in awe of the technological achievement of it all. (For a more detailed description of Dolby S operation than present space allows, see my MSR24S review in February's issue of Sound On Sound.



Previous Article in this issue

Shape Of Things To Come

Next article in this issue

Patrick Leonard


Sound On Sound - Copyright: SOS Publications Ltd.
The contents of this magazine are re-published here with the kind permission of SOS Publications Ltd.

 

Sound On Sound - Aug 1991

Review by Dave Lockwood

Previous article in this issue:

> Shape Of Things To Come

Next article in this issue:

> Patrick Leonard


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