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Soundtracs Topaz

Multitrack Recording Console By Paul White
Published June 1994

Soundtracs Topaz

Soundtracs' new studio gem falls in with the current trend in mixer design – more features and better performance for less money – and adds that special Soundtracs polish. Paul White takes a shine to it.

The battle to build the best budget multitrack console is hotting up, and Soundtracs' new Topaz currently represents the most affordable end of the Soundtracs recording range. I say affordable rather than cheap, because there's nothing about the Topaz that suggests cheapness either in the design or in the build quality.

Like virtually every other multitrack console in this price range, Topaz utilises an in‑line channel topography combined with a conventional split grouping system; to keep manufacturing costs down, all the input channels feature a common front panel rather than adopting the modular approach taken by more costly consoles. Only two mixer sizes are available — 32‑channel or 24‑channel — and there's no automation of any kind, though an optional VCA retrofit is said to be in development. As you'd expect from an in‑line channel design, both the main and monitor signal paths are available for use at mixdown, effectively doubling the number of inputs. Further to this, there are four dedicated stereo Aux returns which, for the arithmetically challenged, means that if you opt for the 32‑channel version, you'll have the luxury of 72 inputs when it comes to mix your magnum opus. Modern MIDI systems tend to gobble up input channels, so having 72 inputs available is most welcome.

Where low‑cost multitrack mixers tend to fall down is in the EQ section; either one EQ section is split between the main and monitor paths or both sections have their own separate, but more limited, EQ system. I'm pleased to say that Soundtracs have given a high degree of priority to the EQ section; what you end up with is a full‑featured, 4‑band EQ in the main channel path and a simpler 2‑band high/low EQ in the monitor path. Though you can't swap the EQs between paths, you can flip the inputs to the main and monitor channel paths, which provides plenty of flexibility when it comes to deciding which of the incoming signals needs the most powerful EQ.

Physically, the console is both simple and attractive, with the rounded end‑cheeks and the countoured (optional) meter bridge lending it a slightly art‑deco feel. The equally art‑deco knobs are tastefully colour coded using pastel‑shaded top caps and marker lines, and although the console is reasonably compact, the layout succeeds in making it feel more spacious than it actually is.

Power for the Topaz comes from a small, rugged external PSU which requires no fan cooling and hence operates silently, and all signal connections other than the mic inputs (balanced XLRs) are on quarter‑inch jacks, which enormously simplifies the process of wiring up. Because the connections are on the rear panel, it is easy to achieve a tidy‑looking installation, especially if the meter bridge is fitted; if there's a down side to this, it is that accessing the console inputs and outputs is quite tricky if you don't want to use a patchbay, especially with the meter bridge fitted.

The master section of the console includes bar‑graph meters for all eight Groups plus the stereo outputs, and the only obvious omission in this area is the lack of an oscillator — though I doubt if this will be considered a major disaster by most prospective purchasers. A nice styling point is the inclusion of status LEDs in the Mute, Solo and AFL/PFL buttons.

Channel High Points

Soundtracs Topaz

Rather than building the usual discrete transistor mic input, Soundtracs have opted for an Analogue Devices low‑noise preamp chip, and as well as individually switchable phantom power, the input stage is equipped with a phase switch — usually one of the first things to go when it comes to meeting a price. The input stage boasts a gain range of 60dB without the need for a pad switch, and the equivalent mic stage input noise is quoted as ‑129dB, though it isn't clear whether this is 'A‑weighted' or not. Either way, it's a very respectable noise figure.

To overcome the limitations of 8‑bus routing when more than eight tape tracks are being used, each channel also has a Bus button which determines the source feeding the module's Tape Out socket; when the button is down, the signal is routed via the Groups in the normal way, but when up, the channel signal feeds directly to the tape output. A further aid to minimising patching is the parallel wiring of the Tape Out sockets, such that Group 1 feeds channel outs 1, 9, 17, and so on, while Group 2 feeds 2, 10, 18, etc. This is pretty much standard practice on current desks and makes the use of 16‑ or even 24‑track tape machines a practical proposition.

The Flip switch has already had a brief mention; its main purpose in life is to swap the main and monitor inputs when it's time to mix, again to avoid repatching. This way, the main signal path may be used for both recording and mixing, providing the greatest flexibility when it comes to equalisation.

I feel the main equaliser is worthy of special note, as it offers an unusual degree of flexibility given the low cost of this console. All four bands provide up to 15dB of cut or boost and both the high and low sections are shelving controls operating at 12kHz and 80Hz respectively. The upper mid has a fixed Q of 1.5 and may be swept from 350Hz to 8kHz while the lower mid extends from 1kHz right down to 50Hz — which means you can get right in amongst the bass frequencies when you need to. An EQ bypass switch is fitted for the main channel, though the monitor high/low EQ is always in circuit. Centre detents are provided for all rotary controls that require a central null position, and even though the pots are attached to large, flat circuit boards, wobble is kept to a minimum because of a deep moulded shoulder on the knob itself, which acts almost as a bearing in the front‑panel hole.

When designing an in‑line channel strip, it can be difficult to decide how to implement the Aux Send controls because, unless they are all made switchable for pre/post operation and all switchable between the main and monitor paths, some degree of compromise is inevitable. Even then, when mixing, there are plenty of occasions when you need to use the same effects unit on both the off‑tape signals and those coming in from sequenced MIDI equipment; for example, you may want to use the same reverb unit on the lead vocals as on the drum machine. Topaz compromises by providing six Aux buses and four Aux Send controls, which are used both for setting up cue mixes and with effects. Aux 1 is pre‑fade and is dedicated to the main channel signal path for use in setting up performers' cue mixes. Aux 2 works similarly but is dedicated to the Monitor signal path.

Aux 3 is a post‑fade send for use with effects and may be switched into either signal path, while the adjacent Aux 5 button redirects Aux 3 to Aux bus 5. A similar arrangement is provided for Aux 4, which is also switchable between the two signal paths and may be routed to Aux bus 6. What this boils down to is that both signal paths have a dedicated pre‑fade, foldback send control, while a pair of post‑fade controls are shared between the two signal paths. Admittedly, they can each be switched between a choice of two buses, but the bottom line is that you can still only use one effect per signal path or two in one path and none in the other.

The Soundtracs Topaz really must be considered an exceptional desk at the price.

Both the main and monitor signal paths are fitted with Solo and Mute buttons and the main signal is controlled via a 100mm fader. Routing to the L,R or Group buses is quite conventional, using a combination of pan pot and routing buttons, though it is possible to send a channel signal directly to the correspondingly‑numbered tape track by using the Bus button. The monitor signal is controlled by a simple level and pan pot arrangement, to provide a stereo mix which may then be fed into the main stereo mix using the Merge button in the master section. This is a nice idea, and aside from adding just a little more flexibility, it means that if the monitor inputs aren't needed at mixdown, they can be removed from the main mix to prevent them from contributing any mix bus noise.

Each channel has a peak LED which checks the signal level in both the main and monitor signal paths and illuminates when the level in either comes within 5dB of clipping. An insert point (stereo jack) is fitted to the main channel path, and it's worth pointing out that the white scribble area below the fader is divided so as to provide space to document both signal paths. Admittedly, there isn't a lot of space, so you'll need a sharp chinagraph pencil.

Master Section

Some mixers I've come across have master sections that are, frankly, confusing: I'll say at once that this isn't one of them. Everything is divided into logical sections, and everything within those sections works pretty much as you'd expect. Right at the top of the panel are the 10 bargraph meters, which are calibrated so that 0VU = +4dBu. The rightmost meters normally monitor the main stereo mix, but if a PFL/AFL/Solo button is depressed, they monitor that signal instead. This is quite conventional, and is of the greatest use when setting up the channel input gain trims. The remaining eight meters monitor the Group output levels so that you always know what level you're sending to the multitrack. Of course, if you're using a multitrack that operates at ‑10dBv, then you're going to have to go by the multitrack's meters anyway, unless you insert matching pads between the mixer and recorder.

Each of the six Aux send busses has its own level control and AFL button, but there appears to be no easy way of combining sends from the monitor and main signal paths, which would make life easier when sharing one effects unit between the two.

All four stereo effects returns include level and balance controls, as well as routing to both the Left/Right bus and to the Group pair directly beneath them. In practice, this means Aux 1 can be routed to Groups 1,2; Aux 2 can be routed to Groups 3,4 and so on. All four have PFL buttons to allow the return signal to be monitored in isolation without affecting the main mix output.

Solo has its own level control and warning LED, while the Monitor mix is simply equipped with a Merge button and a level control. The level control is quite useful as it, essentially, turns the monitor mix into another stereo subgroup, allowing the entire monitor mix level to be varied relative to the rest of the mix using only one control.

Because this is a recording mixer, provision is made to send a signal into the studio area, either to feed a monitor speaker system or a headphone distribution system. A simple arrangement is used, with a single level control and switches which enable the engineer to select Main Mix, Monitor Mix, Control Room, Aux 1 or Aux 2 as the studio feed source.

The Control Room and Phone outputs are both sourced from the same signal but each has its own level control. There's also a Mono button to check mono compatibility, but there's no monitor 'dim' button. The Control Room monitor system may be fed from the Main Stereo Mix, the Monitor Mix or either of two 2‑track inputs, A and B. Two switchable monitor outputs are fitted, allowing two sets of speakers, A and B, to be connected, though there isn't a separate level control for each, which would have been a good idea.

To the extreme right of the console, below a row of three LEDs which confirm the presence of the power supply voltages, is the Talkback section. This is a simple affair and instead of the usual in‑built electret mic, there's a balanced XLR socket which will accept any low impedance mic that doesn't require phantom powering. Other than the Talkback Level control, there are routing buttons to direct the talkback to the Studio feed, the Groups or Aux 1 and 2. Despite what it says in the manual, the main Talkback button isn't non‑latching, which means that you run the risk of a black eye if you insult the drummer having forgotten to disengage the talkback mic. This is probably a shortcoming of this pre‑production sample and there's no reason why the console shouldn't ship with a non‑latching button. The routing buttons are non‑interlocked, so you can talk to any or all destinations simultaneously if need be.

Like the channel faders, the Group and master faders are 100mm‑travel types, and it's worth noting that the Group faders, rather than automatically being assigned alternately left and right for sub‑grouping, each have their own Left/Right routing switch and AFL button. Though not as flexible as a pan pot for each Group, this is infinitely preferable to always having to feed the odd‑numbered groups to the left and the even‑numbered groups to the right. Both the main stereo output and the Groups are equipped with insert points. The optional meter bridge includes bargraph meters for all the main input channels and VU metering for the left and right mix.

In Use

The Topaz was as easy to use as its layout suggested, the only obvious limitation being the rather restrictive Aux Send system referred to earlier. As a recording console is unlikely to need pre‑fade sends at mixdown, it would have made far more sense if the pre‑fade sends had been made pre/post switchable.

Both the mute switches and EQ In switches were checked for clicks, but were found to be quite silent, and the level of crosstalk, both between channels and through the mute switches, proved adequately low.

Equalisers are always difficult to describe because their result is so subjective, but I'd say this one tends towards the workmanlike rather than the esoteric. It has the undoubted benefit of plenty of sweep range, but sounds just a touch unfocussed to my ears.

The layout of the desk is wonderfully clear, and the subdued colours used for the controls make the desk 'a pleasant place to work'. Though the Topaz is obviously designed to be used with budget tape machines operating at ‑10dBv (the multitrack inputs and outs are factory set to this level), it is possible for a qualified service engineer to change these to +4dBu simply by soldering links on the appropriate circuit boards.

One of the prime concerns with any mixer is noise; here the Topaz scores well, both as regards mic amp noise and general mix noise. Providing the gain structure is properly set up by using the PFL metering to adjust the input gain trims, mixer noise is unlikely to be the weak link in a typical recording chain. Mix bus noise is reasonably low, and if you're worried about noise contribution from the monitor section, you can either isolate it using the Merge button or mute unused monitor channels. The latter seems to disconnect the monitor channels from the mix bus, with a consequent reduction in noise. At a comfortable monitoring level, you can kill the input, turn all the monitors and main channels up full, and though the hiss is audible, it's still low enough to ignore.


As a contender for best budget desk, the Topaz has a lot going for it. Its direct competitor in price seems to be the Soundcraft Spirit LC; I feel the Topaz offers far more flexibility in the EQ department, but it loses out when it comes to effects send management.

In most areas, the low cost of Topaz isn't reflected in the quality and number of features provided. The electrical performance as regards noise and headroom is excellent, and all the essential buttons are provided, right down to a phase switch. The only reason why no pad switch is provided is because the Analogue Devices preamp doesn't need one.

When it comes to styling and layout, Topaz again scores very highly. Even without the optional meter bridge, the metering is still adequate for most recording purposes, especially as most users still rely on the meters on their tape machines, not on their mixer. Some people will bemoan the lack of a test oscillator, but to be honest, most of the ones fitted to budget mixers are inadequate for tape machine line‑up, and if you just want to trace a signal, you can always plug in a synth and stand a book on the keyboard!

At a little over £100 per channel, the Soundtracs Topaz acquits itself as a competent and flexible desk able to cope with some quite serious work, and it really must be considered an exceptional desk at the price. Its only obvious weak spot is its effects send handling, but even so, most potential users should find that it's still flexible enough to do the job. The top end of the short list may be a little crowded these days, but from what I've seen, the Topaz deserves to be there alongside one or two other worthy contenders. Inexpensive it may be, but cheap it's not.

Brief Specification


  • All outputs More than +22dBu


  • Microphone (Gain 55dB) 10Hz‑40kHz, +0dB, ‑1dB
  • 8Hz‑100kHz +/‑3dB


  • HF 12kHz +/‑15dB
  • MF1 350Hz‑8kHz +/‑15dB
  • MF2 50Hz‑1kHz +/‑15dB
  • LF 80Hz +/‑15dB


  • HF 12kHz +/‑15dB
  • LF 80Hz +/‑15dB


  • Mic input equivalent (150ohms) ‑129dBu
  • Line input equivalent (50ohms) ‑95dBu


  • 24 channels routed ‑84dBr
  • Signal Crosstalk better than 100dB at 1kHz

Effect Sharing

An in‑line console is really two mixers in one, and problems can arise when you want to use the same effects units on both parts of the mixer. For example, if you have only one main reverb unit, you might want to use it on both the MIDI instruments coming in via the Monitor channels and on the off‑tape signal coming in through the main input channels.

One way around this with the Topaz is to use an effects unit with a stereo input and feed, say, Aux 2 into one side and Aux 4 into the other. This works best with effects units that pass the dry signal through in stereo, but still feed the effects generating stage from a sum of the left and right input. In this case, the dry signal should be turned off. The results will be less predictable if the processor handles true stereo processing, and given that more and more units now offer this, it would have been sensible for Soundtracs to build in a solution to this problem, rather than leaving it to the user to devise a workaround.


  • Lots of inputs.
  • Clear, attractive layout.
  • Predictable operation.
  • Generous EQ capability in this price range.


  • Restrictive Aux Send arrangement.


A well‑specified mixer most suitable for 8‑ or 16‑track users who are looking for high performance on a tight budget, without sacrificing essential features.