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MIDI Interfaces (summer 1989 article)



--- Quote ---Right, so you have your machine ready to load up your chosen piece of music software, you have the synthesizer hooked up to the Amp, what's next?

If you are on the look out for a MIDI interface, you would be mistaken for assuming they are full of complex circuitry and silicon chips. The fact is that a MIDI interface is really quite a simple piece of electronic trickery, a sort of conversion box taking an RS-232 signal and pumping it out at a specific speed to a specific format.

Atari ST

My opinion is that the Atari ST has a pretty naff MIDI interface - built into the side of the machine and containing an IN and OUT socket only (with the provision for a MIDI THRU implemented on the dead pins of the MIDI out), the Atari 520, 1040 and Mega ST has got everything going fqr it even though the hardware driving the two 5 pin DINs is, as I said earlier, pretty naff.

The expansion possibilities seem to be endless however, Steinberg have come up with the SMP-24 SMPTE generator/reader consisting of two MIDI INs and four MIDI OUTs - selling at £919 though you'll have to bank on a few hit singles in order to get it though!

The Steinberg Timelock is a SMPTE Generator/Reader and retails at £399 - whilst not in the same league as the SMP-24, this package is nevertheless the ideal unit for people wanting the SMP-24 without the price.

More in line with the home user, the C-Lab Export unit gives the ST owner three extra MIDI ports for £114 and the Hybrid Arts MIDI-PLEXER which expends the Atari ST from to two MIDI INs and and four MIDI OUTs.


The Amiga has two types of MIDI interface - the Datel and the Mimetics interface, both of which are ideal for the home user, and both offer reasonable networking capabilities.

The Mimetics interface is simply a convertion socket that plugs into the back of the Amiga's serial port - as MIDI information is essentially serial data - the conversion is done mostly in the machine and apart from the opto-isolator inside the connector itself, the Mimetics MIDI interface is really just a D connector with three DIN sockets dangling out of it!

Datel's is a little different - this unit is housed in a plastic case and has one MIDI IN, three MIDI OUTs and one MIDI THRU - it has an LED telling you when MIDI information is active, and is opto-isolated on all channels.

I have been told that Amiga interfaces in general do not take too kindly to long MIDI cables, although things may change as there are new interfaces on their way from MCMCXIX (also known as the Synthesiser Company) and Micro Illusions.

Apple Macintosh

A great MIDI interface to come my way was the Argents MIDI Communicator - coming in two configurations, the top end model - costs well over £300, sits under the Mac itself (styled to fit the underneath, care of four bumps) - on the front are two LEDs that show the mode of operation, and on the back are ten (count them) MIDI sockets - two of them are assigned as MIDI INs and eight of them are assignable as MIDI outs.

The conversion from MIDI IN is done inside the box care of two leads that plug into the printer and the modem sockets - on the side is the MIDI on/off switch and the printer/modem through sockets, so you don't have to unplug a lead in order to print out a file or use a modem.

The MIDI OUTS are individually assignable as two banks of four, so that it is possible to spread the load a little, perhaps have drum machines and effects on one bank of four in the control room, and four sockets feeding the studio itself.

In use I found the Midi interface really reliable - Argents themselves told me "what can you say about it? - MIDI interfaces either work or they don't", and I would concur, but this MIDI interface works well because it worked first time, it never hung up the MIDI network, it accepted some pretty weird configurations and it accepted all of the MIDI composition packages I tried - it will even work with MIDI to SMPTE Timecode conversion boxes such as those from Opcode.

A more affordable MIDI interface is the smaller communicator retailing at £145, it has one MIDI IN and four MIDI OUTs and has one socket to the Macintosh. It is also physically smaller, so it will have to sit alongside the machine.


For my PC, the de facto standard is the Roland MPU-401, but as times change things get upgraded and the MPU-4001 from Passport Octave Plateau/Voyetra steps into the limelight.

Being essentially a serial card with a 25 pin D connector on the back, the Voyetra interface has an additional box that plugs into the D connector - this has one MIDI IN and one MIDI OUT and a FSK sync IN and OUT port.

If you are serious about synching live musicians to tape, an auto metronome is included - this can also be used for more electronic applications but I was not able to try this out other than shoving it through an amplifier.

The  Passport Octave Plateau/Voyetra MIDI interface occupies one half slot inside the machine, but it is full height, so some people wanting to use it inside a laptop portable may not be able to do this - although Passport tell me that it is compatible with the Compact luggable. I tried it out on my Morgan Generic with no problems at all, and it can have interrupt priorities switched as, and when it becomes necessary.

The Voyetra OP-4000 is a simpler model that is compatible with the MIDI sync modes of operation of most sequencers (certainly Master Tracks Pro and Sequencer Plus) - this model costs £168, whereas the OP-4001 costs £198.

Being Roland compatible, Passport are onto a winner, it is compatible with most of the packages I could load into the PC although I was told that Cakewalk had occasional problems with interrupt priorities.

What to look for in an Interface

When buying an interface, you will not need to go over the top and get loads of MIDI INs and MIDI OUTs - if you only intend using a few synths such as a multi-timbral synth and a drum machine, then it is best to opt for a simple one IN, one OUT - perhaps stretching your budget to a one IN two OUT depending on your arrangement at home.

Remember that a MIDI interface is the centre of the MIDI network. Any additional synths may slow down the performance of the network - so all of the old tricks will have to be pulled out of the bag.

With the PC, there are a great many interfaces, two from Passport, one from Roland as well as a strange beast called the IBM Music Feature Card which has an FB-01 built into it, a nice idea, and a good synth as far as I am concerned - but at £395 perhaps it would better to buy the Passport model and buy a cheapo FB-01 from the second hand market!

MIDI setups can be either arranged as Star networks or as Chain networks. A star network is based on the MIDI interface being at the core of the system with a MIDI IN and several MIDI OUTs - a good example is the arrangement I have with the Argents interface, where MIDI information is sent out in one go, but via multiple outputs - great if you have loads of MIDI instruments, but an utter waste if you are using multi-timbral instruments such as the MT-32 and the afore-mentioned FB-01.

For this, you will be better off buying something with less outputs - like the smaller Argents model or the Passport type (one IN, one OUT). Thankfully there are a hundred and one MIDI interfaces with a million different options out there - and depending on the quality of construction, there are a lot of different prices.

Argent's MIDI interface and the  Passport Octave Plateau/Voyetra ones are good examples. I would have no qualms about using these interfaces in the studio and on the road because they are made out of metal and they are rugged yet unobtrusive. Plastic housings are ideal only if you intend keeping your computer and equipment at home, but for pro machines like the PC and the Mac, home designed interfaces are hard to find.
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