MIDI is like a communication language that allows different pieces of music equipment to talk to each other. With a MIDI cable, your keyboard can talk to your computer, and your computer can talk to a synthesizer or sound module.

You might think MIDI is only used in the world of music, since it stands for…

Musical
Instrument
Digital
Interface

…But some people even use MIDI to run lights for theatrical shows.

A MIDI cable is like a tube with 16 little pathways inside it. Each pathway is called a channel. So you can split MIDI information in your computer into 16 different channels, and have it play 16 different instrument sounds on a synthesizer.

If you’re working on a song, your MIDI setup might look like this:

Channel 1: Piano
Channel 2: Guitar
Channel 3: Bass
Channel 4: Trumpet
Channel 5: Saxophone
Channel 6: Trombone
Channel 7:
Channel 8:
Channel 9:
Channel 10: Drums
Channel 11:
Channel 12:
Channel 13:
Channel 14:
Channel 15:
Channel 16:

If you only wanted to use 7 sounds on your synth, you would only use 7 of the 16 MIDI channels.

Most keyboards have MIDI connectors, labeled: IN, OUT and THRU.

You connect the MIDI “OUT” of your keyboard to your computer via a USB port or similar connection, to allow your keyboard to talk to your computer. And you connect your computer to the MIDI “IN” of a sound module, so you can hear the various instrument sounds.

MIDI “THRU” allows you to use more than one synthesizer at a time.

Since most computers have synthesizers built into the sound card that comes with them, your computer might be sending MIDI information to its own sound card.

The beauty of MIDI is that that even an hour-long song can be a very small file, because MIDI is not music; it’s only bits and bytes of information that tells your sound card what to play.

If you emailed me a MIDI file, it would use the sounds from my computer’s sound card. And even though those sounds might be slightly different from the sounds on your computer’s sound card, I would still hear bass where it’s suppose to be, piano where it’s supposed to be, etc.

Each MIDI channel sends a bunch of information. When I press a key on my keyboard, the cable that carries that information to my computer says: “Allan just pressed a key, and the note associated with that key is “G.” It also tells the computer how hard or soft I played the note and how long I held it.

MIDI is incredibly useful. If you just played a magnificent performance, except for a few notes, you can select those notes on your computer screen, and change them to what they should be, and even shorten or lengthen them.

If you played a solo using a guitar sound, you could use the same MIDI track to try out other sounds on your synthesizer - a flute, trumpet, or even a sitar. Since MIDI is only sending information, not sounds, you can keep changing your synth sounds till you find one you like.

You could take the same solo and change the “patch” (preset sound) on your synthesizer to a guitar sound that has effects (reverb, delay, chorus).

To experiment more with the solo, you could copy the MIDI part to another channel. Now you have the same information on two different channels and you can assign the second MIDI channel to a different instrument. So your synthesizer might play your original guitar sound on channel one and the same part simultaneously on another instrument, say a flute, on channel two.

You could even assign the second channel to be percussion, so while your first MIDI channel is playing your monster guitar solo, the second MIDI channel is playing percussion that corresponds exactly to it – because every time MIDI tells your sound module you pressed a certain key, it can tell the second channel to play a percussion “hit” with it.

While MIDI used to be the domain of keyboard players, there are now MIDI wind controllers, so you can blow into an instrument that has keys like a clarinet or sax and it will translate what you do into MIDI information. There are also MIDI guitar controllers.

There are thousands (perhaps millions) of MIDI songs you can download to your computer. And these songs will play using your soundcard’s synthesizer.

If you are a professional musician, you can use MIDI to play higher quality sounds. For example, there are symphonic sounds (both hardware and software) that are actual recordings or SAMPLES of real instruments.

A lot of movie scores and background tracks are played using a MIDI controller (a keyboard, wind controller, MIDI guitar controller, etc.) and software samples (string sounds, brass orchestras, rock guitar parts, etc).

MIDI has changed the world of orchestrating, because now, at the touch of a button, you can try out different textures of music and different combinations of instruments that formerly would have required a live orchestra. And while you may not be able to duplicate what comes through a live musician, you can play with different musical colors to your heart’s content.