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Soundtracs MR Mixer

Multiple output devices like drum machines and sequencers are placing new demands on mixer manufacturers to come up with increased input channel desks. One of the first to respond are Soundtracs with a new range of recording consoles. Dave Lockwood tries out the 24/8/2/model.

The application of multitrack sequencers, drum machines and sync-to-tape in the modern recording process calls for a greater number of input channels on mixers. Soundtracs have borne this in mind on their MR Series and targeted them at the burgeoning 16-track market. We asked freelance engineer Dave Lockwood to put one to the test and report his findings.

The new Soundtracs MR Series of multitrack consoles are available in two mainframe sizes, accommodating either 24 or 32 input channels, with an 8 subgroup output/master section equipped with 16 monitor channels and a host of useful additional features. The unit is very substantially constructed from heavy gauge materials, but in a desk of this size (the 24 channel review model measures just over 4½ feet in length), this is certainly both necessary and desirable to achieve the rigidity essential for reliable operation over an extended period.

The back edge of the stylish console houses an integral meter pod, creating an ideal viewing angle for the attractive array of LED bargraph meters. The ten element displays, turning from green to yellow at 0VU, offer adequate resolution for most purposes (3dB steps), and facilitate the metering of up to 16 group/tape return signals, as well as the master outputs and solo buss, plus a switched option to read the auxiliary busses. In addition to displaying a tastefully illuminated Soundtracs logo, the meter panel also gives discrete confirmation of the presence of the correct supply and 'phantom' voltages from the heavy-duty external power supply unit, which connects to the rear panel of the desk via a short multicore cable fitted with latching six-way XLR connectors.


The input channels are very comprehensively equipped, and contain all the features that one would consider necessary in a multitrack console designed for use in a professional environment. The channel input gain control can be varied over a 40dB range (+20 to +60dB), and operates, on the mic input, in conjunction with the 20dB 'Pad' switch, to ensure optimum signal level through the channel. The mic inputs utilise the only XLR connectors to be found on the rear panel (all other signal connections being quarter-inch jacks of one format or another), and are low impedance, balanced (wired Pin 2 'hot', Pin 3 'cold', Pin 1 ground), with an individually switchable 48 volt 'phantom' supply for the remote powering of condenser mics or, increasingly these days, phantom powerable 'active' DI boxes.

The channel Line input (10kOhm input impedance, quarter-inch jack) is, like all the other line level connections to this desk - unbalanced. Although more sophisticated balanced or differential line level inputs and outputs obviously can offer theoretical advantages in minimising noise and interference, in practice, I have never actually encountered problems of this type with unbalanced line level signals, even in relatively hostile electronic environments, provided that decent quality cables and connectors are used throughout the system.

A 'Phase' switch, offering the facility of phase-reversal on both mic and line inputs, enables unwanted phase cancellation to be avoided when a number of mics are used in close proximity to each other, or indeed sometimes, for such cancellations to be deliberately created, either as an effect or in an effort to reduce certain elements of microphone crosstalk or 'spill'. Phase reversal of one of a pair of mics can also be advantageous when miking a small open-backed combo amp from in-front and behind simultaneously, or a drum from both above and below.


The MR Series input channel features a comprehensive equaliser, with an 'EQ In/Out' switch enabling easy comparison of the 'flat' signal with the EQ'd sound, and also taking the equaliser stage out of circuit when not in use.

A low frequency (high-pass) filter can be switched in, independently of the EQ status, to create a 12dB per octave roll-off below 100Hz. The filter slope and chosen frequency seem subjectively just about right for tightening up signals with no very low frequency content without unduly affecting the low midrange.

The main equaliser consists of a shelving low frequency control (the term 'shelving' implies that all frequencies beyond the nominal operating frequency are also boosted or cut to the same degree) offering +/-15dB to 50Hz, a similar shelving high frequency control (+/-15dB) operating at 12kHz, and two mid-frequency controls of the 'sweep' or quasi-parametric variety. In a true parametric equaliser all three parameters are variable: frequency, gain, and 'Q' (bandwidth). However, that level of sophistication is rarely required on a mixer and a fixed bandwidth is usually adopted, as in this instance, giving a useful 'bell-shaped' response, which is both narrow enough to be selective on sounds, yet sufficiently smooth to avoid resonance effects associated with steep, high 'Q' filters.

The high-mid control operates over the range 500Hz to 10kHz, whilst the low-mid covers from 50Hz to 1kHz, both offering 15dB of amplification or attenuation. A useful degree of overlap occurs in the midrange, whilst extending sufficiently at both extremes to integrate with the fixed HF and LF bands, to cover effectively the whole of the usable audio bandwidth. Unusually, the frequency controls are marked with actual operating frequencies all around the travel of the pot, rather than just at both ends, as is most often the case with sweep controls. Whilst your ears must obviously always be the final judge of any EQ setting, I feel it does help to know where you are starting from, and to be able to make a precise note of an effective set-up. This is a thoughtful touch from Soundtracs which, like all the high quality legending on this model, contributes to the ease of use of the desk.

Equaliser performance is a very subjective area, and difficult to rationalise, for the theoretically most effective system, or the unit that produces the best measurements, may not always be the one found to produce the most musically useful results. Some people, myself included, have a degree of aversion to the kind of colouration that can be perceived as being introduced by a typical sweep EQ system, particularly when acoustic sources are involved. However, unlike the purists, I would not attempt to deny their general usefulness, particularly in rock music. Indeed, the now almost universal inclusion of this kind of EQ in desks for multitrack work can be taken as an indication that most audio signals are not adversely affected.

When used with sensible moderation, as any EQ should be of course, and with particular attention paid to avoiding excesses in the midband, this Soundtracs EQ can be both subtly effective and highly selective, in creative or corrective use. Boosting at upper-mid or high frequencies inevitably introduces some HF noise, but in general the noise level within the channel, post-equaliser, was subjectively every bit as low as one expects in equipment of this calibre.


Particularly well equipped in the auxiliary department, the MR Series offers a total of six mono sends with a useful variety of pre/post fade options. Auxiliaries 1 and 2 are fixed pre-fade, primarily for foldback applications, and normally operate post-EQ as expected, although an internal PCB jumper link can be altered for pre-EQ working if necessary. Auxiliaries 3/4 and 5/6 are switchable in pairs to either pre-fade or post-fade operation, making a potential total of six pre-fade sends for headphone mixes, or four post-fade sends suitable for effects, available at various stages of recording and mixdown. Certainly enough to cover most normal(?) working requirements.

Further effects or external signal processors can be introduced into individual channels via the insert points provided on the rear connector panel. These are quarter-inch stereo jacks, wired with the 'send' on the ring, the 'return' via the tip and the sleeve as ground, and are located in the circuit after the EQ, which I have always found to produce the best results, particularly with level-sensitive processors - gates, compressors etc.

A red 'peak' LED located as usual (mistakenly though I always feel) close to the top of the fader travel, indicates the level within the module at the insert return point. Illuminating approximately 5dB below the onset of clipping, it enables optimum, safe signal level to be maintained by giving a visual indication that is inclusive of the EQ and any gain occurring at the patch-point. If the LED illuminates consistently, it is of course the channel gain control, external device output, or boost element of the EQ that must be reduced, for lowering the channel fader (the instinctive reaction of many inexperienced operators) can have no effect on an overload occurring earlier in the circuit.

Input channels can be routed on the MR to any, or all, of the 8 subgroup outputs, with individual group selection being achieved in the conventional fashion of paired odd/even group select switches operating in conjunction with the 'Pan' control. Stereo subgroups are thus easily recorded by pre-panning a number of signals into their required positions across any pair of adjacent odd/even groups, at the record stage, such as when recording several drums and overhead mics as part of a close-miked stereo kit balance.

A channel 'Solo' function, with its own LED column and illuminating red 'Solo' sign, permits monitoring and metering of the input in isolation, without interrupting the main signal paths within the desk. The solo signal is derived pre-fader, but post-insert and post-EQ, so that the combined effects of equalisation and any external processing are always heard. 'Solo on' condition is also indicated by a green LED within each channel module which, in conjunction with the 'Solo' metering (which only illuminates when in use), should prove impossible to overlook - an important point as it can be surprisingly easy when working under pressure to waste time looking for the mysterious 'fault' that has silenced the monitor mix, before discovering a soloed auxiliary buss in some remote corner of the desk!

The 'Mute' switch provided silences the channel's outputs (although the insert point and solo functions remain active), with an appropriate red LED clearly confirming mute status. The switch is effectively noiseless in operation, as was all the switching on the review model, with the curious exception of the input channel 'Mic/Line' and 'Phase Reverse' switches, which produced a significantly audible 'thump'. Fortunately, this did not affect the normal usage of the desk during trials as these facilities are practically never required to be switched during actual recording or mixdown. Given the high standards generally displayed throughout this product, I feel safe in assuming that this was due to a minor fault peculiar to this example, and not typical.

The channel faders are professional, long-throw types (Alps 100mm) with a superbly smooth action, allowing very fine resolution around the principal operating area, and offering in excess of 90dB attenuation. The wide P&G-style fader tops, and the glide action with just the right amount of resistance, make these faders a real pleasure to handle.


Although only 8 group outputs are provided, the Soundtracs MR Series features 16 monitor channels, facilitating easy monitoring of a 16-track recording. The 8 upper monitor channels (9-16) can be individually switched for monitoring their tape return signal or the output of the subgroup below, so the choice of monitoring the 'live' signal or the recorder's signal remains independent of the tape machine's monitor logic. This is, I feel, preferable to the situation found in many desks that have a greater number of monitors than groups, where the additional channels can usually function only as tape returns, thus making it almost essential to record on those tracks first in order to maintain an easy group/return monitor switching facility during later overdubbing.

All six auxiliaries can be accessed by the monitor channels, although (presumably as a means of saving space) the six sends have been condensed to four pots, with auxiliaries 3/5 and 4/6 being simultaneously fed by ganged controls. The pre/post-level control options are maintained however, making it possible to set up several different headphone foldback mixes, whilst still retaining a post-fade send suitable for employing reverb in the monitor mix.

The Mute and Solo functions, with supporting LEDs, are also present on the monitor channels, acting on either the group or tape return signal according to the monitor status. Usefully, visual indication of signal is maintained by the metering even when a monitor is muted. The expected 'Monitor Level' and 'Pan' controls complete the well-equipped line-up of facilities on the upper set of monitor channels.

In addition to the above, monitor channels 1-8 include a basic three-band EQ and fader-reverse option, significantly extending the usefulness of the desk in the latter stages of the recording process. In fader-reverse mode, the group fader exchanges functions with the monitor level control and, in conjunction with the equaliser, makes available up to 8 additional line input channels for use during mixdown, all of which can be EQ'd, controlled by high resolution faders, and sent to all six auxiliary busses. The EQ, which consists of shelving HF and LF bands offering +/-15dB at 10kHz and 100Hz, with a +/-10dB mid control operating at 1kHz, is more than adequate for most purposes.

As always with a desk offering EQ on the monitor channels, it is important to establish that all the monitor EQs are set to 'flat' when initially setting up sounds through the input channels, otherwise some rather odd settings can occasionally occur simply through trying to counteract the effect of an overlooked monitor EQ - perhaps a monitor EQ In/Out with a warning LED would have been of practical value in this situation.


The reason for the provision of such a large number of controllable line inputs is unlikely to be just to cater for effects returns, but probably has more to do with the increasing prevalence of the use of sequencer controlled systems and drum machines, all synced to tape. With a 16-track recorder, as would most likely be used with this console, it would not be altogether impossible to find 8 extra synth voices, and at least another 8 separate outputs from a drum machine, driven from a single sync track on the recorder, and all presented as additional sources at the mixdown stage! This may seem like an extreme example, but with 15 tape signals, 1 sync track, and 16 'live' signals, the 24 input channels plus the 8 lower monitor channels would only just suffice, and would still necessitate the more basic upper monitors being pressed into service to accommodate any effects returns.

A number of the wide variety of currently available desks suitable for 16-track work seem to have anticipated such possibilities to some extent, but few can offer quite this degree of flexibility combined with such simplicity of use. The 32 channel version of the MR Series would, of course, cope easily with systems of even greater sophistication and could be employed quite happily, I would imagine, with a 24-track machine, with input channels used to handle the extra monitoring tasks. Indeed, this larger version of the desk could offer a remarkable total of 48 line inputs on re-mix, with 40 of these having long fader control and EQ!

The single chassis unit that contains the group/monitor channels also houses the stereo master faders and a number of other facilities and master controls. All six auxiliary busses have master level controls in this region, each with a useful post-level control solo facility (auxiliary can also be individually metered, without being soloed, by means of a row of switches in the upper monitor channels arranged so as to swop any, or all, of the meters reading tape returns 11-16 over to displaying an auxiliary master level). A master 'Monitor Level' control is provided, as well as an independently controlled headphone feed - the headphone socket is located right in the middle of the master panel, but this is thoughtfully duplicated on the rear connector panel to cater for any long-term usage, such as feeding a secondary monitoring system or set of small reference speakers.

Facilities are also included for switching between monitoring the output of the stereo buss or the returns from either of the two 2-track machines that can be connected to the desk, with a separate return level control for matching playback levels. A 'Mono' switch provides a summed left and right signal, for 'radio mix' simulation or phase-checking, whilst a monitor 'Dim' facility provides a handy 15dB monitor attenuation - a more useful feature than it may appear, for it can assist in maintaining a degree of consistency in the working monitor level, by allowing the listening level to be temporarily reduced whenever necessary, but always returned to the same level.

A talkback circuit, which can access groups and auxiliaries for track titling or communication, is a useful inclusion. Activated by a momentary switch, it also automatically dims the monitors. The front panel XLR socket accepts a balanced, low impedance mic input but in any semi-permanent set-up, such an arrangement, necessitating either a mic and stand with a cable, or a gooseneck, is hardly the most elegant or convenient of solutions: a built-in talkback mic would have been preferable. Unusually, a separate Solo level control is provided, governing the level at which the solo buss is fed into the monitoring - the absence of this facility on many desks can mean the occasional nasty surprise when monitoring at very high levels, and its inclusion here is a welcome safeguard!

An oscillator, switchable between 30Hz and 1kHz, can be routed to both groups and auxiliaries for basic line-up or cue tones, and could also prove useful for fault-finding, either within the desk or the whole system.


Although many consoles now offer a choice of standard operating level, usually achieved by altering internal switches or PCB jumpers, the Soundtracs range makes the selection of the required interface level even easier. All line level inputs and outputs (with the exception of the main input channel line inputs which have their own gain controls) utilise stereo quarter-inch jacks, but instead of the balanced signal that this would normally imply, they are wired to offer a full line level +4dBm signal on the tip circuit, and a -10dBV (Tascam/Fostex) line level via the ring circuit. This ingenious arrangement not only ensures trouble-free, user-selectable compatibility, but also enables equipment of both standards to be mixed, temporarily or permanently, and with the simplest of cabling arrangements.


Probably the easiest way to use an 8 group desk with a 16-track recorder is to parallel the group outputs into pairs of recorder inputs, so that group 1 feeds tracks 1 and 9, group 2 feeds tracks 2 and 10 etc, leaving the recorder's own switching to determine which tracks are actually recorded (the arrangement of both the metering and the group monitoring in fact seems to assume this method of operation). In most instances, this will almost certainly prove entirely satisfactory; however, you can't be certain that you won't ever want to record on more than 8 tracks at once, and in a more permanent set-up-and most certainly in commercial studio use - I would want to utilise a simple external patchbay, albeit perhaps a 'normalised' one, with 'normal' connections made as above, in order to be able to readily make use of the direct outputs conveniently provided on every input channel. These outputs are post-EQ, post-insert, post-fade, and provide an excellent means of sending any individual (as opposed to part of a group) signal to tape. With 8 groups, and as many direct outputs as there are input channels, simultaneous 16- or even 24-track recording should prove no problem at all for this desk.

For normal 16-track applications, it is possible to leave the outputs of the tape machine permanently connected to the line inputs of mixer channels 1 - 16, as these are internally connected to the monitor channels when in tape return mode. This means that mixdown requires no re-patching, but merely the selection of line-in on the appropriate channels, thus saving not only time and effort, but also wear and tear on the cables and connectors.


Despite its size and apparent complexity, I'm positive that the Soundtracs MR Series would present no problems to anyone already familiar with conventional subgroup/monitor style desks (as opposed to the 'in-line' variety). The clear layout and well-conceived procedures ensure that wherever confusion could arise, such as in the switching of the auxiliary options, the front panel graphics and legending are an effective guide.

At this level of price/performance, clean, quiet electronics tend to be taken (quite rightly) for granted, with differences in sound quality between rival manufacturers' systems very much the subject of distinctly esoteric argument. On a more practical level, I am content to report that I found all aspects of the subjective audio performance of this desk in every way satisfactory, in all configurations and circumstances of use.

The Soundtracs MR Series may not be loaded down with the latest digital routing features, or 'computer controlled, programmable SMPTE-linked muting' and the like, but it is nevertheless a most comprehensively equipped desk which is able to handle applications well beyond the basic 16-track recording tasks. Indeed, in terms of fundamental facilities, it cannot be faulted in any significant way.

If further evidence of the success of this design were needed, I would have to mention the surprising speed with which I was able to feel completely at home with this desk, with everything seeming to fall to hand as required, and operating in an entirely predictable manner, no time therefore being wasted in picking up unorthodox procedures, making it immediately possible to concentrate on the subject itself, the sound, rather than the mechanics of the operation.

In my experience manufacturers' slogans seldom bear close examination, but in this case, 'affordable quality' was never more apt.

MR Series prices: 24 input £5000 plus VAT; 32 input £6118 plus VAT.

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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 - Mar 1986

Donated & scanned by: Bill Blackledge

Gear in this article:

Mixer > Soundtracs > MR 24/8/2

Review by Dave Lockwood

Previous article in this issue:

> A Taste of Paradise

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