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Digital Music Corporation MX8

MIDI Patchbay Processor

Article from Music Technology, September 1988

From America: a 1U-high black box which combines MIDI patching, merging and processing capabilities. Vic Lennard encounters a new twist in MIDI processing.

What do you get if you cross a MIDI patcher with a MIDI merger and a MIDI effects Processor? Answer: the Digital Music Corporation MX8.

MEET THE MX8: a black 1U-high 19" rack-mount MIDI patching unit designed to solve at least some of your MIDI interconnection headaches. The MX8 will accommodate six controllers and eight modules. At first glance the front panel is rather sparse - power; two cursor keys, which are used to move the cursor around various screens on the 32-character backlit window; data entry No/-1 and Yes/+1 buttons; a Function button for selecting the monitoring and editing operations, and a Reset button for sending an all-note-off command to every output on each channel.

With 50 memories, the MX8 will allow you to send any control data from any controller to any output and permit each setup to be saved along with a 10-character name. And there's more: two independent processor channels (A and B) each of which can carry out any of the processing functions available, and can also be merged together.

Basic Operation

BEARING IN MIND those 50 memories, on power-up you are confronted with memory 51: the Edit buffer, which will have been saved from the last time that the machine was used. Press the function button and the following appears:

IN 11112222 1>A
OUT 12345678 2>B

This is the initial setup, and tells you that input (controller) 1 is passing through processor A and also being sent to outputs (modules) 1, 2, 3 and 4; input 2 is passing through processor B and going to outputs 1-8. In fact, processors A and B are redundant in this particular situation because they have no output. Now consider the following setting:

OUT 12345678 2>B

M represents the merged signals from processors A and B. Let us say that in this situation, input/output 1 is a Roland PR100 sequencer, input/output 2 is a sequencer on an Atari 1040ST, input 3 is a mother keyboard and the rest of the outputs are for various modules. The idea is for the Atari sequencer to control the PR100 and for each of the sequencers to control modules from their own programmes. Consequently, input 2 is sent to output 1 (giving the PR100 an external clock), input 1 is sent to processor A (to filter out its clock) and the two processor signals are merged to control the rest of the modules using only one clock signal. Although input 2 is being sent to processor B, it isn't being used in this particular example, but has to be sent there in order to merge the information.

This brings us to a couple of minor problems. Firstly, each output has to be fed from an input - you cannot bypass an output as you can with the Yamaha MJC8 or by leaving a channel blank as with the Akai ME30P. This is quite a bind as you have to be very careful to ensure that something important is not being sent somewhere it isn't needed. Secondly, while the two processors are independent, if they are merged together processor B loses part of its independence, in that it cannot then be used to control an output. I assume that the data from processor A is fed into processor B, and so while you can branch off between the 2 processors, you cannot do likewise at the output of processor B. It appears that this isn't really merging, but the passing of info, from A through B. Mmmm...

What's in a Process?

PRESSING THE FUNCTION button brings up "EDIT (Y/ N)? PROCESSOR-A" in the display. The cursor keys are used to toggle between processor A and processor B. Pressing data entry "yes" takes you through the following pages:

- Process Channel allows any of the 16 MIDI channels to be selected, or Omni for all of them.

- Filter allows note on/off, aftertouch, control changes, program changes, pitch bend, system exclusive common and system exclusive real time to be filtered out. Each filter has its own screen with a status indicator which can be set to on or off.

- Velocity Limit is a nifty idea which works along the lines of a compressor/limiter. A minimum and maximum velocity can be set such that if the input note velocity is less than the minimum threshold it will be increased to the threshold (for example: a minimum threshold of 40 would result in an incoming value of 13 being scaled up to 40). And similarly for the maximum.

- Map Range allows three split points to be set up, thus creating four zones across a keyboard. Now your DX100 can act as a mother keyboard because each region can have its own MIDI channel. Zones may not overlap.

- Transpose permits transposition of between -64 and +63 semitones.

"Zoning: Map Range allows three split points to be set up, thus creating four zones across a keyboard - now your DX100 can act as a mother keyboard."

- Velocity Xswitch will select a different MIDI transmit channel for notes above a set threshold velocity. Excellent for drums, for instance, if a different sound is required to accent certain sections.

- Channel Shift has two modes of working: offset and reassign. Consequently, all data can be shifted up by a set number of channels, or assigned to one particular channel.

- Delay allows a specified number of repeats to be set up with velocity offset for each repeat. Echoes can either fade away or crescendo, a different channel from the original signal can be set and delays are possible in either a number of 16ths at a particular tempo (for instance, half a bar in 4/4 time would be represented by 8 followed by the tempo in beats per minute - or in milliseconds between 5 and 3000). The page can be bypassed by setting the number of repeats to zero.

- Exit returns you to the routing screen.

Apart from these specific processor functions, and remember that there are two independent processors, there are also the following features:

- Program Change allows the controller for either processor to send patch changes to the MX8 on a specific MIDI channel. This is a global feature in that if it is on, it will be on for all 50 memories.

- Patch Chain. On loading a setup, a patch change can be sent to each synth. This is achieved by specifying the output for the module, the MIDI channel and the program number to change to. Care will have to be taken if more than eight synths are being used and Thru connections from some are leading to others.

Finally, setups can can be named, saved to one of the 50 possible locations and reloaded as required.

Safety Aspects

ITS REASSURING TO see a company trying to anticipate future problems and allowing for them within the design of the machine, as Digital Music have here. Firstly, because the 10 bits making up a MIDI byte take 320 microseconds to be transmitted, a Dynamic Filter has been included. Data to be output is queued up in a buffer and once the queue is 30 milliseconds long, pitch-bend and aftertouch information are filtered out. Pitch-bend data which would reset to zero is passed through to prevent the embarrassing situation of a very out of tune synth. Should the buffer overflow, a "MIDI Data Overflow" message will appear and an all-notes-off message will be sent out. This appears to be similar in operation to the overflow indicator and data reduction techniques used in C-Lab's Creator/Notator packages.

Secondly, because not all synths respond to all-notes-off messages there is an extra safeguard. Holding down the Reset key will send the all-notes-off followed by a velocity-0 message on each channel. This will be interpreted as a note off command, and will continue to cycle round the channels until the key is released.

Perfect in Practice

ABOUT A YEAR ago I encountered the tenet "MIDI means never having to say that you have enough equipment". I'd have to go along with that. I'm used to using the eight-input Yamaha MJC8 MIDI junction Controller, so I wish that the MX8 also had room for eight controllers. Nevertheless, I wired it into my studio and used it exclusively for a week or so. Gripe number one: the screen is in desperate need of a contrast control as it's very difficult to read from many angles. Secondly, it would have been helpful to have had some sort of visual output monitor - an important feature when things start to go wrong - certainly, a visual warning of when the dynamic filter starts to work would have been a godsend.

Complaints aside, this unit is packed with features that I am most certainly going to miss when I have to return it. The MIDI delay is astonishing, especially with its ability to increment/decrement velocity from repeat to repeat - I don't think that anyone will use a digital delay on MIDI equipment ever again. Also, the MX8's ability to send a complete setup of MIDI patches at the beginning of a song simply by pre-programming them into a memory is great for live work, as is the Reset control on the front panel (although a foot switch á la 360 Systems Midimerge+ would be nice).


ANYONE WITH A sequencer and more than one keyboard has certainly wished for many of the features on the MX8 at some time or other. At a RRP of £395 the MX8 is half the price of some of the big boys, but also twice the price of a basic MIDI switcher or merger. But given its facilities, there really isn't anything else available to match it. I know that I have raised one or two points of concern, but perhaps I am being a little pedantic as it does the job it is designed to do - and well, into the bargain. I reckon that Digital Music Corp have a winner on their hands.

Price £393.95 including VAT

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Publisher: Music Technology - Music Maker Publications (UK), Future Publishing.

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Music Technology - Sep 1988

Donated & scanned by: Mike Gorman

Gear in this article:

MIDI Patchbay > Digital Music Corporation > MX8

Review by Vic Lennard

Previous article in this issue:

> Communique

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> Cookin' The Mix

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