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On the Rack

Tanrack modular effects rack

Modular effects for the home studio

The Tanrack: not absolutely perfect... excellent value.

The Tanrack is a modular rack system following in basic design concept those of Scamp and Rebis. The system components are unusually inexpensive especially if you are prepared to make them up from kit form. Up to eleven modules plus power supply can slot into the 4U (7" high), 19" rack mounting sub rack, and considering that many of these are stereo devices, it's a very compact package. The modules are guided home via plastic locating tracks. At the bottom of the rear edge of each PCB is a 10-way female connector which is pushed home to mate with the pins of its corresponding male half on the mother board which forms the rear of the rack.

Along the bottom of the mother board run the ten bus tracks that link the connectors of the eleven modules and the power supply. Holes are punched in the board for the input/output jack sockets mounted on each of the modules to protrude, thus forming a simple patch bay. If you intend to have the sub rack free-standing this should cause no difficulty, but bolting it into a larger rack system would obviously necessitate bringing the sockets out somehow to another patch bay. All the standard input and output sockets are normalled together, via the busses, through their break jack connections. This means that a socket is connected to the busses until you insert a jack plug, at which point the bus connections are broken and the jack connections take their places. In this way it is possible to simply plug a signal into the far left hand unit and take it out of the far right hand, using the individual module in/out switches to determine the processors actually in line. If you want to use the rack as a whole, or simply want more control over the level of a certain input, the Input Module provides front panel access with extra level control plus LED metering.


Should you decide to save your money and go for the kits, you will find that no great technical expertise is required to put them together. A knowledge of resistor colour codes and which end to hold the soldering iron should prove sufficient. Each module is built on a single, double-sided PCB. They are very neatly laid out with all the IC's on holders as standard, and I am told that the PCB's supplied with the kits will have the shapes of the components etched on to them. The designs have been optimised for a line level of -10dB although they will also work will 0dB or directly from the output of an electric guitar. The choice of colour scheme is not one that falls easily upon these eyes: brown and black with big orange knobs. But whatever you think of the cosmetic, the finish is of a high quality.


When digital took over the world of audio processing, analogue got a bad name; and in many cases it was quite justified. The charged coupled device or bucket brigade circuit simply isn't up to producing long, wide bandwidth delay times, but that doesn't mean it ain't good for nothing. For effects such as phasing/flanging, chorusing, ADT, pseudo stereo etc, which require short delay times, the well designed analogue device will often do better than its digital alternative.

With one input and two outputs the Multi-Delay can produce a stereo effect from a mono source and claims a 12kHz response for a delay of up to 44ms. Increasing the delay results in a rapid and very audibly deterioration until you get something like 3kHz bandwidth at 180ms. In practise 44ms is enough for a huge range of effects, although I have to disagree with the manufacturer and say that natural sounding reverb isn't one of them. It definitely won't replace even a moderate spring device when it comes to that. An automatic limiter is to be found at the input which is brought to bear only on the signal going to memory, and not the direct signal. Thus the noise level is kept to a surprisingly acceptable minimum while avoiding the unpleasant effects of pumping etc often experienced with fixed parameter limiters. A generally richer and more convincing range of effects is produced by the use of six fixed delay taps, as opposed to just one or two, distributed three per side about the two outputs.


The Modulation Oscillator is obviously needed to allow many of the effects mentioned (flanging, chorusing, etc) to be created. It produces a variable frequency waveform with a continuously variable shape at two outputs each with individual depth adjustments. Whilst it was designed with the Multi-Delay in mind, it can also be used to modulate other voltage controlled devices. 'Key Depth' allows the depth of the effect to be controlled by the level of the input signal, and the 'Key Trigger' switch will cause the modulating oscillator to commence a new cycle each time a new signal is presented at the input. Both these facilities add greatly to the subjective musical power of the effects and are very much a bonus on a device of this price.


A straight forward single channel parametric offering a bypass switch and four variable controls: level, centre frequency, bandwidth (0.1 to 3 octaves), and again. It operates from 35Hz to 1.2kHz and then from 350Hz to 12kHz with the help of a x10 switch. It works well, and once again, at the price it's hard to fault it.


This is very much a gate and not an expander gate: once the signal level has dropped below the threshold, a switch is opened and no further signal is allowed to pass. There's no question of a gain reduction — it simply switches off and on. Many gates will have a control to determine the gain reduction resulting from passing the threshold, and if the main intention is to unobtrusively mitigate spillage or background noises, this is a very important facility.

However, that's not what the stereo Pro Gate was primarily designed for. It was designed to accomplish all the other 'effects' applications that a gate has, such as the almost unmentionably popular gated reverb plus the various forms of keying, like white noise on to snare drums, and strings on to vocals etc. It's fastest attack time of 200 microseconds could be a little faster, but on the other hand I know of no other unit at this price that offers this level of performance with threshold, attack, hold and release controls plus a key input.


The stereo Dynamic Noise Filter, on the other hand, is extremely effective in reducing tape hiss from a recording. It is basically a self-adjusting low pass filter whose cut-off frequency changes according to the high frequency content of the programme that it senses above a certain level. It is a stereo device and is best used at the final mixdown stage just before the mastering machine. This is hardly a new idea, but at the price it's quite excellent, and I truly believe that every budget home set-up should have one.



Description Kit Built
Pro Gate £34.95 £48.95
Compressor/Limiter £38.95 £54.95
Dynamic Noise Filter(2) £33.95 £47.95
Parametric Equaliser £34.95 £48.95
Analogue Multi Delay £79.95 £110.95
Modulation Oscillator £33.95 £47.95
Input Module £32.95 £46.95
Output Module £32.95 £46.95
Psychoacoustic £39.95 £59.95
Enhancer £33.95 £42.95
Power Supply £39.95 £47.95
Sub Rack £ 8.95
Dust Cover Set
Infinite Flanger Available soon
Mic Preamp Available soon
Mixer Available soon

Not only does this stereo compressor/limiter have full control over ratio, attack and release, but it also includes a key input to allow use as either a 'ducker' for voice overs or, in combination with an equaliser, as a de-esser. The attack time could be a little faster and I would prefer to see a series of LED's to show gain reduction as opposed to a single multicoloured LED, but in consideration of the price such gripes are possibly rather churlish. It works very well.


Some people love 'em, other's can't hear the point. Personally I've never been a great believer in this type of effect which claims to add an extra dimension and fullness to the sound through the generation of extra harmonics. The original device that started it all was the Aphex Aural Exciter, and while this unit doesn't quite have the smoothness as the top of the range Aphex, it works tolerably well — if you like that sort of thing. You'll have to take a listen for yourself.


Though it is possible to criticise the performance of the Tanrack modules as being not quite absolutely totally perfect, in consideration of the price I have to say that they are generally excellent value and can definitely be recommended to those with a limited budget.

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Electronic Soundmaker & Computer Music - Copyright: Cover Publications Ltd, Northern & Shell Ltd.


Electronic Soundmaker - Sep 1985

Donated & scanned by: Chris Strellis

Review by Jim Betteridge

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