Basic MIDI Connections

By Rick Long

Despite the fact that MIDI (Musical Instrument Digital Interface) has been around for a few years, I am often asked to explain how to make basic MIDI connections. The problem is that MIDI seems to be one of those things that people either know a little about or they know a lot about. Those that know a lot about it often are not willing to take the time necessary to explain the basics to those that know only a little. This article is for those that know a little about MIDI and want to know more. If you know a lot about MIDI, keep reading because you never know when you are going to learn something new. I learn something new about MIDI almost every day and I've been doing this for a few years.

Basic Computer MIDI setup

MIDI 101: OK class, lets review what we've learned in past articles. MIDI is a standardized protocol developed by the manufacturers of electronic music devices that allows devices from one manufacturer to "talk" or pass information on to devices made by other manufacturers. The first use was to connect two keyboards together so the keys on the first keyboard would play the sounds you liked on the second keyboard. More recently, MIDI is used for connecting keyboards or sound modules to computer so they can record and/or playback MIDI sequences. A MIDI sequence is like a recording of the music you just played, only instead of recording the audio sound the computer records the "sequence" in which you played the keys, how hard (or how fast) you pressed them, and how long you held them down. When you press "play" on a MIDI sequencer or on sequencing software , the sequencer or computer sends the information back to the keyboard (or sound module) and the keyboard plays the music "live."

The first hard concept about MIDI connections is that the cable used to connect two MIDI devices together runs from MIDI OUT to MIDI IN. A mistake people often make is that they run the cable from the MIDI OUT on one device over to the MIDI OUT on the other device. Bottom line is, this doesn't work.

The concept is that the device you are playing needs its output to go to the input of the next device. In other words, on the keyboard you are playing you want to use MIDI out. This sends the signal to the MIDI IN on the keyboard or sound module that you are trying to trigger.

Trigger, by the way, is a generic term for "play." If I want to trigger the sound for Middle C on my synthesizer, I press the key for Middle C. On an electronic drum kit, I could trigger a particular sound by hitting the pad that is associated with that sound.

You will see another MIDI connector (also called MIDI port) on the back of some devices called MIDI THRU. This port is used for connecting more modules to the chain. Here's an example. Let's say you are playing a keyboard that is just a controller. This means that they keyboard doesn't have any internal sounds or maybe just a very few. The keyboard is designed solely as a "triggering" device for MIDI modules. You will connect the MIDI OUT of this controller to the MIDI IN of a sound module. When you press the keys on the keyboard, you trigger the sound module to play the same notes using the patch that you selected.

Let's say you have two sound modules and you want to use some of the sounds in both of them for your performance. Your first connection is from the MIDI OUT on the keyboard to the MIDI IN on the first sound module. To get the second module to play, you run another MIDI cable from the MIDI THRU on the first module to the MIDI IN on the second sound module.

Now that you can run the cabling, let's talk about setting up the sounds. The keyboard that you are using will have some manner for switching the patch or voice selection. The term "patch" has been around for many years. Early synthesizers (circa 1970's) were made up of rack-mounted modules: an oscillator that created the basic sine wave (the basis for the sound); a filter module that modified the tone of the raw sine wave; and various other tone shaping modules. To get the sound you were looking for, you had to connect a short guitar cord or "patch" cord, from one module to the next. When you got the sound you wanted, you would write down the "patch" configuration so that the sound could be reproduced later on.

Today, a sound on a synthesizer, be it a piano sound or a violin sound, is often referred to as a "patch." You will also find the term "voice" used to mean the same thing. A preset sound is one that is "pre-set" within your sound module. In other words you didn't have to string up the patch cords. The sound was already programmed into the unit for you.

When you change the patch on the keyboard, a signal is sent through the MIDI cable called a "patch change." This tells the computer chip inside the sound module to call up a certain patch. When you change your keyboard to patch 37, the sound module will go to patch 37 as well. This is a good time to check out the side-bar on General MIDI Review.

In a multi-module setup like Figure 1, the problem becomes getting the two modules to play the correct patch without having to manually set the module each time you want to change patches.

More expensive keyboard controllers have the capability to send patch change messages to each module separately. These controllers have more than one MIDI OUT and you can connect each module directly to a MIDI OUT on the controller. You select the "out" you want to use and the patch change you want to select by pressing buttons on the controller.

A work around for keyboards without this capability is to setup each of the modules to receive on different MIDI channels. Most MIDI devices have the capability to handle 16 channels. Some of the newer MIDI equipment allows for 32-channel capability. By setting module one to receive on MIDI channel 1 and the second module to receive on MIDI channel 2, you can now play the modules separately by changing your keyboard between MIDI channels 1 and 2. When the keyboard is sending its data out on MIDI channel 1, the first sound module will play. When the keyboard is sending its data out on MIDI channel 2, the second module will play.

When using sequencing software, the problem is solved a bit differently. Sequencing software includes an area for "system exclusive data" or "sysx" (sis-x) as it is commonly called. After going to the module and manually setting up the sound you want on the channel you want and turning all the other channels off, you can save the settings to the sysx area of the software. When you playback the sequence file you are working on, the sysx is streamed out over the MIDI cable and the module is returned to the setting you created. Each module has a unique sysx ID so the software is able to send the sysx out and the modules recognize the information that is specific to that module.

In a more complex MIDI setup (see above figure), you can play sequences on the computer and play the keyboard "live" along with the sequence. In this case, you could set each module, along with your keyboard, to receive data on separate MIDI channels. In the sequencing software, you can set a separate track for your keyboard and set that track to the MIDI channel you choose for the keyboard. Place the patch change data in that track window and now you won't even have to change the patch on the keyboard. When the file plays back, it will automatically set your keyboard to the correct patch for you.

The other modules in the chain should be setup as mentioned earlier, with sysx saved from each one. This way you can program one module for some of the MIDI channels and the other module for other MIDI channels. You would want to do this because one module might have a better bass sound than the other might while the other had a better piano sound than the first one. This way you can have the best of both modules available to you at one time. On the sequencing software, you won't put patch data in the track windows for the module MIDI channels because this was already done when you setup the module for channels to receive and patches to play on those channels.

GENERAL MIDI

The term "General MIDI" (GM) refers to a standardized set of patches agreed upon several years ago by keyboard and sound module manufacturers. The GM standard was developed to allow players to record sequences on one type of keyboard and then play them back on any other keyboard that had the General MIDI (GM) sound set. There are 128 patches in the world of GM, starting with "acoustic grand piano 001" and going on up to 128 with patches that include everything from bass guitars to violins. They are numbered consistently but you will find that more expensive keyboards generally have higher quality sounds associated with those numbers.

This is not always true. Some inexpensive keyboards I have heard include very good GM sounds. If your budget isn't up to the latest, greatest equipment, don't be afraid to try something that is less than top of the line. You may be pleasantly surprised at the quality available today. This is so because top of the line keyboards and sound modules contain hundreds if not thousands of non-GM sounds. A lot of research and development money had to go toward these extra sounds. A less-expensive keyboard or sound module may have a very good GM sound set since that is all the unit offers.

Listed to the right is a set of General MIDI sound sets.