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Programmable Audio Patchbays

Peavey MAP8X4, Icon Research APB1

Ian Gilby takes a look at two different approaches to the design of a MIDI-controlled audio patchbay: the Peavey MAP8X4 and Icon Research APB1.

Patchbays are an essential means of maximising flexibility when routing audio signals from one device to another but they can hardly be considered interesting. Add MIDI control and patch storage, however, and we're talking a whole new creative ball-game. Ian Gilby checks out two different MIDI-controlled programmable audio patchbays.

As MIDI permeates ever deeper into the control aspects of recording life and equipment manufacturers come up with even more innovative ways of utilising the power of the five-pin DIN, it is becoming too easy for us all to fall foul of 'information overload' and to cheerily dismiss certain new products without genuinely appraising their worth and the potential benefits they can bring to our own MIDI setups. This is particularly true of products which fall into that less than glamorous category of 'peripheral accessories' - such things as switchers, routers, mergers, splitter boxes and, of course, patchbays. Yet, ironically, these are the very devices that can benefit users most from the appliance of MIDI control and programmability. To demonstrate this point, let's take a look at two examples...


The APB1 and MAP8X4 are both MIDI-controlled programmable audio patchbays. The APB1 is the first product from fresh-faced British company Icon Research and costs £499, whilst the MAP8X4 hails from American stalwart Peavey and costs £369. MIDI-controlled audio patchbays are not a new invention, of course - Akai led the way with their MB76 Mixbay back in late 1987 [reviewed SOS March 1988], and various companies have subsequently followed in their footsteps. But the two products under scrutiny here offer more advanced facilities and superior audio performance, and as such represent a worthy progression. The APB1 can take up to eight audio inputs and route to any of 12 outputs, whilst the MAP8X4 can accept four inputs and route them to any eight outputs.

So why does anybody need a patchbay? The basic function of a conventional audio patchbay is to act as a central routing point, taking all inputs and outputs from various pieces of equipment and allowing them to be interconnected, or 'patched' together, in the most flexible way possible. This is usually achieved by plugging all the input and output connectors into sockets on the rear panel of the patchbay. These are then rarely ever touched.

A duplicate set of connections is provided on the patchbay's front panel, and the required interconnections between certain inputs/outputs are made by inserting a short cable, or 'patch cord', to link the desired output to the desired input. If at any stage the output needs to be routed to a different input, it is simply a matter of unplugging the cord from one input socket and re-inserting it into another. Having all the connections close at hand and in one place is far more convenient than stretching around the back of your mixing desk, tape recorder, and synthesizers etc, plugging and unplugging cables every time you want to connect things differently (the same holds true for MIDI patchbays).

The downside of such audio patchbays is that you still have to undertake a certain amount of repatching each time you want to route an output signal to a different destination. And if your patchbay has a very large number of inputs and outputs, then you will probably need to create a 'patch sheet' - a written record of what is routed where - so that the next time you come to mix a particular song you recorded six months earlier, you can remember how to reconfigure your patchbay so that your rackfuls of synth expanders are routed to the appropriate mixer channels etc.


Patch sheets have a nasty habit of going missing five minutes before a studio session starts, so a better means of storing and recalling each patch would be a boon, as would the ability to give meaningful names to them, eg. 'HitSong 2' or 'Wondertune 7' etc. This is where modern technology comes to the rescue.

With devices like the APB1 and MAP8X4, connections are still made to (¼" jack) sockets on the rear panel in the time-honoured fashion, but the front panel patching is done via electronic switching rather than cables and the routing configuration is stored in internal battery-backed memory, instead of on a patch sheet, for rapid and convenient recall.

The MAP8X4 offers 128 possible patch memories, whilst the APB1 ups the ante slightly to 150. (I can't see why anyone would ever need more than this number, can you?) The APB1 also has the advantage of being able to assign 12 character names to every input and output (eg. 'EffectSend2', 'S1000 Left' etc) and a 16-character name to individual patches. These are stored in memory as part of the patch data and displayed in the unit's backlit LCD window. The Peavey MAP8X4 lacks this useful facility, with patches being identified in the three-digit red LED display purely by their assigned memory location number (1-128).

In both cases, stored patches can be recalled remotely by sending each machine a MIDI program change message from a keyboard, sequencer, or some other MIDI controlling device. You are free to assign each patch to the program change number of your choice. In addition, the APB1's utility functions let you call up patches using MIDI note or song numbers instead of just program changes. This can prove very handy when using a sequencer to change patches remotely, and where there is no spare MIDI channel available to dedicate to controlling the patchbay. This clever feature allows you to utilise very low or very high note numbers (out of the musically useful note range, of course) within an existing music sequence to change the patchbay setup as and when needed, without switching programs on any other MIDI gear you also have set to that same MIDI channel. (This only works if you can set the 'notes received' range of the sequenced instrumentation so that it is above/below the lowest/highest notes you intend using to trigger your patch changes on the APB1. Most synths will let you do this, though.)

As if to reiterate its professional orientation, the APB1 also provides full control of patch memories and front panel control functions via a rear panel RS232 port. A five-pin DIN socket is employed instead of the more usual 'D' connector, and the well-written and comprehensive manual details the necessary hexadecimal codes for those wishing to delve further into computer control. Also on the rear panel is a standard BNC output for connecting an external video monitor to the APB1. This is a great idea, as it gives a full visual status report of all the input/output connections on screen, whereas the LCD - clear though it is - only shows the currently active connection. I tested this feature with a Philips green screen monitor I previously used with my old BBC B computer, and it worked fine. Suitable monitors can be picked up secondhand for around £50, and the benefit of having a large, easy-to-read screen display in your studio is well worth the modest extra investment if the APB1 happens to take your fancy. No such facility is offered by the Peavey patchbay.

Although both patchbays can be controlled via MIDI, the Peavey unit scores over the Icon Research APB1 in the fact that it allows either individual patches or all 128 patches to be dumped (and retrieved) as System Exclusive data to a MIDI storage device like the Alesis DataDisk or Elka CR99, or to any sequencer capable of recording SysEx data. Recording your patchbay configurations at the beginning of each sequence, before the notes start, allows them to be recalled with the relevant tune each time it is played. At present no SysEx dump is available on the APB1, primarily because the UK manufacturer has yet to be assigned an official MIDI Manufacturers' ID number. Hopefully, this will be remedied soon.


In some ways it is unfair of me to compare these two units, because they have not really been designed with exactly the same functions in mind. The APB1 is a very well built, beautifully noise-free, and rather clever replacement for a conventional 8x12 audio patchbay, but with all the added benefits of MIDI control, optional video display, and programmability.

The Peavey unit is not really a direct replacement for a standard patchbay, it has been designed primarily to allow up to four effects processors to be patched into any of eight possible audio channels, in any combination. As such, it would prove extremely useful in any recording setup where several effects units are being shared across multiple input channels - as on a mixer auxiliary bus. How come? Let me tell you...

If your mixer has only one effects send (auxiliary) bus and no direct outs on the input channels, then unless you connect separate effects units in-line with each mixer input signal (costly, and you'll need plenty of them!), then the maximum number of effects you could utilise on each sound source would be one (assuming your effects units do not generate more than one effect simultaneously that is).

With the Peavey MAP8X4, however, you could connect up to eight of your mixer channels at a time and up to four effects units, using the rear panel send/return jacks. You can then select which effects are assigned to which input channels and save the setup as one patch (you can have up to 128, remember). In this way, up to four effects could be routed to any number of the eight inputs in any combination you like; you could even route all four effects to the same channel(s), in any order you like, for chained effects treatments. Suddenly your mixes are no longer confined to having just reverb or just echo on your signals - you could have echo plus reverb on three channels, say; chorus, pitch shift, and echo on two others; and phasing with delay and reverb on the remainder.

By calling up different stored routing patches on the MAP8X4 (either manually, or remotely via MIDI) in combination with effect program changes on your four effects units, it would be possible to change the effects mix as often as you wanted throughout a song! I can think of no easy means of achieving the same result on a single auxiliary mixer without using a MAP8X4.

Owners of cassette-based multitrackers, which often have only one or two effects sends/auxiliaries, could benefit enormously from this unit. As could any home recordist looking to make their present equipment setup stretch a bit further by maximising flexibility.

A front panel Trim control is provided to set the optimum return signal level from each connected effects unit. Since effects processor output levels can vary considerably from model to model, this is a truly welcome feature. Thanks Peavey.


The Icon Research APB1 and Peavey MAP8X4 come highly recommended. Although both are programmable audio patchbays, they serve different functions (as outlined above). The APB1 costs more but has more to offer than the MAP8X4 and should appeal to professionals (a balanced version is also available for an extra £100) as much as it will to serious amateurs. The silent switching of the APB1 is particularly welcome for those intending to change patches on-the-fly whilst audio is still present.

On face value £369 may appear a lot when compared to the price of a conventional audio patchbay, but in the case of the Peavey MAP8X4 it is not too much to pay for the tremendous flexibility it can bring to any recording situation - especially mixing. For those of you already making good use of MIDI equipment in your studio, isn't it about time you considered automating your audio routing as well? If you agree, you could do no worse than to opt for either (or both) of the review units.


APB1 £499 inc VAT.

Icon Research Ltd, (Contact Details).

MAP8X4 £369 inc VAT.

Peavey Electronics (UK) Ltd, (Contact Details).

Also featuring gear in this article

Previous Article in this issue

The Sensual World of Kate Bush

Next article in this issue

The Pursuit Of An Obsession

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 - Apr 1990

Donated by: Bert Jansch / Adam Jansch


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