Setting up a MIDI system

Matthew Bacon explains the ins and outs of setting up your own MIDI system

During the early 1980s, the international music industry was in a state of flux. Punk and Rock music was giving way to a new kid on the block, electronic music. As musicians ditched their guitars for electronic synths and samplers, a new era of popular music was being born.

Atari Corporation was surfing the crest of this technological evolutionary wave thanks to the inclusion of MIDI ports on its new home computer, the Atari ST. Nobody knows for sure why Atari decided to do this. Some believe that it was at the request of MIDI instrument manufacturers such as Yamaha, Roland and Casio, while others claim it was simply a stroke of genius.

Whatever the reason, it allowed the Atari ST to become the computer of choice for musicians composing in the new musical genre. Today, almost two decades later, the ST remains a reliable and solid choice for anyone wishing to learn and experiment in the art of sequencing.

The aim of this article is to explain (as jargon free as possible) how to set-up a basic MIDI system containing your Atari ST/Falcon030 and any other MIDI devices that you own. However, it is not within the scope of this article to discuss or explain how to use any of the MIDI devices - sorry!

What is MIDI?
MIDI is the acronym for Musical Instrument Digital Interface. The specifications of MIDI were conceived in the early 1980s to enable electric musical instruments from any of the industry's manufacturers to work flawlessly together. However, MIDI is more than simply a hardware interface. For an electric musical instrument to call itself a MIDI device, not only must it feature one or more MIDI ports (the hardware interface), it must also understand the MIDI protocol.

The MIDI protocol is a binary language that uses a series of instructions (called MIDI messages) to accurately convey a musical performance as electronic data. MIDI messages are generated by a MIDI device whenever a user interacts with it. For example, whenever a note is pressed down or released on a synth, a series of MIDI messages (collectively known as MIDI data) are generated.

By using a MIDI device called a sequencer to record these MIDI messages, an accurate reproduction of the performance can easily be produced at anytime by playing back the recorded data to the MIDI device! Not only that, by manipulating the MIDI data recorded and stored by the sequencer, the performance can be changed without any loss of quality.

For MIDI data to be recorded or played back, the sequencer must first be physically connected to the MIDI device generating the MIDI messages. This is achieved using a cable with a 5-pin DIN connector at each end called a MIDI cable.

A basic MIDI system
A MIDI system consists of at least two MIDI devices. MIDI devices come in many guises such as synths, samplers, sequencers, sound modules, controllers and drum machines. To connect two MIDI devices together (if doesn't matter which), all you need to do is connect a MIDI cable from the MIDI Out port of one of the devices to the MIDI In port of the other.
 

As easy as this sounds, a common mistake is to connect either the ports or MIDI devices the wrong way around. For example, if you were to connect the MIDI In of a MIDI device to the MIDI In on another device, nothing will happen (the same applies to MIDI Out).

To combat this common mistake, I have found it helpful to imagine the direction or journey the MIDI data will travel. For example, to hear a note pressed on the MIDI controller played on the sound module in Figure 1, you would need to connect the MIDI Out of the controller to the MIDI In of the sound module (as shown below).
 

However, if you were to connect the MIDI Out of the sound module to the MIDI In of the controller, you would not hear the note played. The reason for this is that the MIDI data is travelling in the wrong direction (as shown below).
 

To help you understand what happens when a user (such as yourself) interacts with a MIDI device, here is a brief explanation of what would happen if a note was played on the MIDI controller in Figure 2.

After the note on the controller was pressed down, MIDI "note on" data would be generated. This data would include MIDI messages detailing which note was pressed and how hard. The MIDI data generated would be sent from the controller's MIDI Out port, along the MIDI cable to the MIDI In port of the sound module. Upon receiving the MIDI data, the sound module would execute the instructions it contained (which note was pressed and how hard), thus playing the note. The note would continue to be played until either the sound module was switched off or a MIDI "note off" message was received (which would be sent by the controller when the note was released).

Make sense? Good. Of course, the best way to understand what happens is to see it - and hear it - in action.

Typical system configurations
Now you know how to connect MIDI devices together, below are examples of a few typical MIDI system configurations. As you will see, each subsequent example increases in complexity as further MIDI devices are included.
 

Figure 4 shows how to configure a basic MIDI system containing two MIDI devices. In this example, a MIDI synth is connected via two MIDI cables to a ST/Falcon030 running a sequencer. This is an ideal set-up for MIDI novices as it allows MIDI data to be both record and played back.
 

Figure 5 shows how to configure an intermediate MIDI system containing three MIDI devices. In this example, a MIDI controller is connected via a single MIDI cable to a ST/Falcon030 running a sequencer. The ST/Falcon030 is then connected to a sound module.

This system configuration takes advantage of what is known as the MIDI Thru port. Most MIDI devices have three MIDI ports, a MIDI In, a MIDI Out and a MIDI Thru. As we have already discovered, the MIDI In port is used to receive MIDI data, while the MIDI Out port is used to transmit MIDI data. The MIDI Thru port can be extremely useful as it re-transmits MIDI data received by the devices MIDI In port. By using the MIDI Thru port, it is possible to "daisy-chain" MIDI devices together (as shown in Figure 6).

However, to complicate matters, Atari decided to combine the MIDI Out and MIDI Thru ports on the ST/Falcon030. This can sometimes cause MIDI data received by the computers MIDI In port not to be re-transmitted from the MIDI Out/Thru port. The reason for this is often because the MIDI Thru option has not been selected in the software which is being run. This can be extremely frustrating and is worth keeping in mind when using the MIDI Out/Thru port on your Atari.
 

Figure 6 shows how to configure an advanced MIDI system containing four MIDI devices. As in the previous example, a MIDI controller is connected via a single MIDI cable to a ST/Falcon030 running a sequencer. The ST/Falcon03 is then connected to a MIDI sampler which is in turn daisy-chained to a sound module using the sampler's MIDI Thru port.

When using a configuration similar to that in Figure 6, it is important to place MIDI devices in the correct order, as some do not have MIDI Thru ports. A potential problem when using the MIDI Thru port is known as MIDI delay. MIDI delay is caused when too many MIDI devices are daisy-chained together. Although MIDI data travels at relatively high speed, the longer the path the data is required to take, the more chance there areof errors occurring.

One of the golden rules when setting up a MIDI system is to keep the MIDI cables as short as possible. Before you start blaming your equipment, check your cables are not too long!
 

Figure 7 shows how to configure a complex MIDI system containing five MIDI devices. In this example, a MIDI controller and drum machine are both connected to a ST/Falcon030 running a sequencer. This is achieved by using a MIDI merger box to combine the MIDI data generated by the two devices to produce a single output. The ST/Falcon030 is connected to a MIDI switcher which is in turn connected to a sound module and sampler. The MIDI switcher - as its name suggests - allows the MIDI data to be switched between the two destination devices (the benefits of this will be explained in a future article).

As you can appreciate, we have only just begun to scratch the surface of what MIDI is capable of. In a future article I will tackle the subject of MIDI files and any questions you may send in after reading this article.

Finally, if you only remember one thing from this article, please remember that before configuring any MIDI system, you should always work out how you are going to connect each and every devices on paper first! Although this may initially appear to be a waste of time, it can potentially save you hours of frustration - believe me.

Happy music making!
 

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MyAtari magazine - Feature #5, April 2002