What is MIDI and How Can I Use It?

Posted on by Dave Eichenberger


Anyone reading through the specs of an effects processor or has ever bought a keyboard has seen the word MIDI. What is this crazy thing, and will it make my guitar sound like an 8-bit Atari game? Am I going to have to dig out my protractor and sextant to understand how MIDI works? This article will demystify this protocol and showcase how MIDI can make our guitar rig work more logically and efficiently.

What does it mean, anyway?

MIDI stands for Musical Instrument Digital Interface. Back in the 70s, if you were a keyboardist and you wanted different sounds, you needed different keyboards. Fast forward a few years, and manufacturers came up with their own ‘language’ which would allow their own keyboards to talk to each other. In other words, with just a cable, you could play one keyboard, and hear the sound of both keyboards without having to press the keys of the second keyboard. Problem was, it only worked if both keyboards were made by the same manufacturer.

In 1982, a common language was developed that allowed devices from any manufacturer to speak to each other. This was a big deal, as most companies were very protective of their technology, but feared that incompatibility would eventually lead to less sales. So they worked together to allow a way for different pieces of gear from different companies to speak to each other.

MIDI isn’t a type of sound, it is a language

This sounds nothing like Jimi Hendrix.

This sounds nothing like Jimi Hendrix.

To explain this, it is much easier to understand if we use keyboards as an example. MIDI is a protocol which can send a message to a specific instrument. In other words, it tells the instrument what sound to use (program change message), what key to play (note 0n message), how hard to hit the key (velocity message) and to add more reverb (continuous control message). It can also be used to back up the sounds or update the firmware (system exclusive message). Of course, there are many more types of messages, but these are the basic ones.

So, you connect them all together?

In receives the messages,  while out & thru sends them to the next device in the chain.

In receives the messages, while out & thru sends them to the next device in the chain.

Well, yes, by using a MIDI cable like one pictured at the top of the article. It is a 5-pin cable that has to be plugged in to all the device in the daisy chain. Most midi devices have three sockets: MIDI Out, In & Thru. MIDI Out is where you plug in the first cable- it sends messages from the first device to the second. MIDI IN is where you plug the cable into the second device. It is receiving messages from the first device’s MIDI Out. A cable from one device’s midi THRU just sends whatever messages it receives from the first device THRU the second device and out to the third. This is what you would use to daisy chain devices together.

So: MIDI Out>MIDI In>MIDI Thru>MIDI In>MIDI Thru>MIDI In…etc. Out is generally used only on the ‘master’ device – the first one. It’s controlling the sounds on all subsequent devices.

Yeah, but, um, I play guitar….

This is a midi footcontroller which stores all of the instructions for the devices it controls.

This is a midi footcontroller which stores all of the instructions for the devices it controls.

In the 80s, when giant racks full of blinking lights were pushed onto every stage, MIDI was used to switch sounds. A foot controller was at the guitarist’s feet, and when he/she pressed a button, it told the first device to turn on a chorus, the second to add a compressor, and the third to turn on a delay set for a specific time. Each device was on a unique channel, so it wouldn’t get confused by listening to instructions meant for another device.

This did mean lots of programming for the guitarist, since each effect unit had to be programmed to get the right sound and the footcontroller had to be programmed to send the right message to the right device. This was before computers made programming easy – usually you had to stare at a very small LCD screen. To make matters worse, some commands used the MIDI language, which is in hexadecimal (base 16) language. Yeah, fun.

Now all of this is tedious, and really the opposite of just rockin’ out. However, it is pretty cool to step on a button and change the entire configuration of your rig. On one patch, the expression pedal controlled the wah, on another, it controlled the delay time. Those precise sounds which were only available in major studios could be had by programming those sounds into your rack effects, and programming your foot controller to select those sounds.

OK, this makes me happy I didn’t grow up playing guitar then

Well today, MIDI means a few things to guitarists. It can mean MIDI guitar, which adds a hex pickup to your guitar, and tells a synth what sound to play, what note to play, and for how long. I have used a MIDI guitar system for years, and it is a blast triggering choirs and piano on guitar.

However, most guitarists today are using MIDI for just a few things. Programmable amps allow you to set the knobs any way you want, and then save it. You then use a foot controller to select a specific sound (program change message) and possible modify that sound, like raising the gain for the solo (continuous control). In other words, program change messages select a specific patch (or program), and continuous control messages allow you to change the sound by modifying a parameter within the same program.

Keep your effects off the floor...

Keep your effects off the floor…

Far more common in the world of guitar these days is the programmable effects switcher. While multieffects allow you to string together multiple effects in one box, the programmable effects switcher allows you to use your own stompbox collection. Each effect gets plugged into the switcher (usually housed in a rack- the effects go on a shelf in the rack too), and pressing a button on your foot controller sends a message to the switcher to switch on specific effects. Sometimes it is difficult to stomp off a chorus, delay and compressor, then switch on two distortion boxes, a long delay, and a phaser in the time between a verse and a chorus.

The switcher saves the on/off status of each effect as a program. Your foot controller uses a program change message to send the switcher a command, and it automatically plugs your stomp box into the audio path. This keeps the pedals off the ground (and safe) while taking ones that aren’t on out of the audio path until you need it. There are no patch cables between effects that can go bad at a show, and when you aren’t using any effects, it is like you are plugging directly into your amp.

MIDI can change the sounds in a virtual Guitar Rig too.

MIDI can change the sounds in a virtual Guitar Rig too.

With computers and iOS devices so prevalent in our lives, it has made programming the right sounds for our songs so much easier. No more decoding hexadecimal commands, and no more bending over a 2 x 24 character LCD screen. Most programming is icon-based, and logical. Sounds are more easily shared among communities online too, and there is always help available in online forums.

Are you the kind of guitarist who meticulously sculpts your sounds, or do you just plug in and rock? Do you use MIDI for anything in your guitar rig?

Written on March 10, 2014, by Dave Eichenberger

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