MIDI (Musical Instrument Digital Interface) was created in the early 1980’s to allow musical instruments such as keyboards, synthesizer and drum machines from different manufacturers to work together. Up until that point, each one had their own respective analog methods of getting everything to synch up.
While MIDI is still around and going strong, it’s becoming sort of a dead language as more and more people are turning to VSTs that work within their DAWs. Regardless, anyone that is interested in or has electronic music equipment should know the basics.
MIDI is NOT audio
The first lesson is the most important one. MIDI is a set of signals between pieces of equipment, much like how computers operate on a network. MIDI (DIN) cables do not transmit audio and separate audio cables must be run to mixers and audio interfaces for each piece of equipment being used.
The exception is that some equipment that runs MIDI over USB can also run audio. Of course that’s an exception within an exception, in a manner of speaking, because most equipment with USB MIDI won’t run audio at the same time and if it does, you need a host computer with a client software installed to run the audio into your DAW.
So what does it do then?
The most common analogy people make when discussing MIDI is to compare it to an old fashioned player piano. MIDI is sort of like the roll of paper you would load into the piano: it tells the piano what note to play and for how long. It can also send plenty of performance data at the same time such as information from the expression and sustain pedals, patch changes or pitch bend.
Now that we have the basics down let’s examine some of the mechanics of MIDI.
The MIDI cable
The cable you will use to connect your equipment together uses a connector called a DIN (Deutsches Institut für Normung). Each MIDI cable carries 16 individual channels of MIDI information simultaneously to each piece of equipment. Each individual MIDI channel also carries the entire spectrum of MIDI commands allowing for a high level real time control over each device.
That’s just a fancy word that means a keyboard or other piece of equipment can play more than one sound at a time on a different MIDI channel. With the addition of a sequencer, it’s possible for one person to perform and record all the separate parts of a composition and have the keyboard play them all back at once.
Most workstation type keyboards that come loaded with sounds such as pianos, drums and guitars are multitimbral up to 16 channels. Synthesizers on the other hand may or may not be multimbral and if they are, they may only be 2, 4 or 6 parts. The cool thing about MIDI here is that you don’t have to use all 16 channels on one instrument. You can maybe use two on one and perhaps four on the other.
Tip – Most keyboards and synthesizers that are multimbral change how their effects are configured when they are in multitimbral mode. This is because the keyboard or synthesizer’s CPU isn’t capable of processing effects on separate sounds at the same time and the keyboard may either turn them off or only allow you one or two effects depending on the keyboard you are using. Most people work around this by recording each sound separately in single (or monotimbral) mode after they’ve completed the composition.
In, Out and Through
The cool thing about MIDI is that it lets you connect different types of equipment together. There’s a whole range of keyboards, synthesizers, drum machines, samplers and sequencers you can use to create you composition with. As I mentioned earlier, you can use any combination of MIDI channels across you gear so long as you don’t exceed the 16 channels per your one MIDI connection.
You can think of connecting gear in this way as if you were making a chain with an an anchor on the end. For your anchor (the first device in the chain) you most typically would use a computer with a DAW and MIDI connection or a hardware sequencer, either a stand alone one or one within a workstation keyboard.
You would then connect a MIDI cable from your sequencer’s MIDI OUT connection to the MIDI IN connection to the second device in your chain. Now here’s the tricky part: from the second device you connect it’s MIDI THROUGH to the third device’s MIDI IN. You then repeat the process for each device left in the chain.
The difference here is that the OUT connection is used to send signals directly from one device to another; that’s why we connect the OUT from the sequencer to the IN of the second device of that chain. Using the THROUGH port of the second device passes the instructions from the sequencer onto the next device.
I know that’s a bit confusing, but you have to understand that everything in our chain so far is passive; meaning that none of our devices do anything but respond to signals from the sequencer. So if you connected the third device’s IN to the OUT of the second, it wouldn’t do anything because the second device isn’t sending instructions and there would be nothing to pass onto the fourth device.
Let me give you an alternate scenario as an example. Say you were doing some sort of house music and you’ve written several of the parts on a keyboard with a sequencer; maybe a piano groove and a slap bass. Now in addition to that you also have a drum machine with a built in sequencer. One the drum machine you’ve written your drum patterns and sent a bass line pattern to a synthesizer.
In this case, since both the keyboard and the drum machine have sequencers, we can get them to work together by changing the way we hook them up. We would connect the IN on the drum machine to the OUT of the keyboard. And then connect the IN of the synthesizer to the OUT of the drum machine. This time we aren’t using the THROUGH port because both devices send signals directly to the next device in the chain.
You may be wondering by this point how each device knows what to play and what to ignore. That’s a good question because you don’t have to use all of the MIDI channels on each device at once if you don’t want to. On each MIDI device there is a MIDI menu that will allow you to specify how it responds to incoming MIDI signals.
One of the most common and simplest MIDI scenarios is using a computer to sequence a multimbral keyboard. In this setup we have a keyboard in multimbral mode with it’s MIDI IN connected to the computers MIDI OUT and the keyboard’s MIDI OUT connected to the computer’s MIDI IN.
This small MIDI loop allows us to use the keyboard to enter notes into the computer’s sequencer and then have the computer sequence the keyboard. There is one little trick we have to know for this to work properly; we have to turn “Local Control” to off in the keyboard’s MIDI menu. This disconnects the keyboard from it’s internal sound engine so that it only sends MIDI notes to the computer. If it wasn’t turned off, you’d hear all sorts of strange sounds from the keyboard as it played what you played and also what it played from the MIDI going into and out of the computer!
Within your DAW you will have several MIDI tracks that you want to send out to your keyboard. Within the DAW you would be able to select these channels, the sound for each to play on the keyboard and other options. Each track has an option to “arm” or “record” that when activated, allows you to play from the keyboard into that track and none of the others. That way you can play back your composition and record along with it.
Now lets extend on that scenario. Say you were using MIDI channels 1-4 on your keyboard and wanted to play 2 parts on channels 5 & 6 on a synthesizer. To set this up, you would have to add a MIDI cable from your keyboard’s THROUGH connection to the IN connection of the synthesizer.
And once more there’s another little trick we need to know to get this to work right. In both the keyboard and synthesizer’s MIDI menu there is an option called “OMNI” and we need to turn it off. If it’s turned on, the device will respond to all incoming MIDI channels. So in this case, if it was not turned off, the keyboard would respond to channels 5 & 6. We don’t want that, so we turn it off. Next, we have to go back and make sure that our devices are in multimbral mode and then turn on each MIDI channel in the MIDI menu for the ones we do want the device to respond to.
Wow that’s allot to cover! But it’s the basics and it will get you up and running, so lets move onto the more advanced stuff.
By this point as well you may be wondering what the messages are that make MIDI work. There is several types of information that gets transmitted over MIDI and we can break them down into groups based on their function.
This is section of MIDI that controls anything you hear, to put it simply. Contained within the performance controls are note on & off values and sustain, damper pedal, pitch bend, and velocity information as well.
A subset (so to speak) of the performance controls are MIDI CC (control change) commands. The CC commands allow you to connect either a control or value with a parameter. Usually CCs can be programmed into MIDI controllers and sequencers whereas in contrast synthesizers and keyboards have their own dedicated controls, even though they will respond to MIDI CC.
Let me give you an example. Say you want to record a cut off filter sweep on a synthesizer into a sequencer. After making the appropriate MIDI connections you would then program a knob on the sequencer (or on a MIDI controller connected to the IN of the sequencer) with the appropriate CC number for the synthesizer’s filter cut off control. You then start recording on the sequencer and perform the sweep to record it. When you play back your composition, the sweep will play back, having been recorded as part of it.
In this way, CCs can be used to control just about every parameter of MIDI device’s internal sound engine. This gives you powerful control for creating and memorizing performance setups in a sequencer. To give you an idea of range of possibilities, check the MIDI implementation chart in your keyboard or synthesizer’s manual.
Tip – Many keyboards and synthesizers have module or rack versions which make them more portable, but they also lose the ability to be edited with few or no controls on the front. They’re great for saving space and they are also cheaper too! Many of the MIDI control surfaces and keyboards on the market today can be programmed with just about any MIDI command, making them excellent for programming rack modules!
NRPNs (Non Registered Parameter Numbers) is a part of MIDI that was sort of left blank. It’s a defined area within MIDI in which musical equipment manufactures are free to use for their own products like CCs. By far, the most common use of NRPNs is to define how sounds are selected on keyboards and synthesizers. Within your sequencer or DAW you can select per channel the sound on the keyboard or synthesizer you want to use for that composition. When you save it in your DAW or sequencer, it will be there the next time load it.
Learning to use NRPNs and CCs is a good way to automate allot of the housekeeping tasks that you tend to get into with sequencers.
SysEx (System Exclusive) is not a part of MIDI, but it transmits over the same cables and can be used in many of the same ways. SysEx is a set of instructions that are unique to each MIDI device and are used to transfer things to and from the device such as custom patches (a group of settings that tell the sound engine how to make a particular sound, also called presets) and other information such as firmware and OS (operating system) upgrades.
Tip – In the 1980’s, SysEx was used in much the same way MIDI CCs are today. Many of keyboards and synthesizers also lacked on board controls for editing. So be careful when buying them: you’ll need a controller or MIDI device than can be programmed to send SysEx values if you want to program it!
Last but not least, GM stands for General MIDI, which I’m sorry to say it isn’t some guy in the Army but rather a stock set of sounds that come on GM compatible keyboards. The quality of the sounds will vary from keyboard to keyboard, but the order of the sounds will be the same. This is so that people can transfer GM MIDI files that they have created on their sequencers to someone else, who can load them and play them back using the same sounds. It’s also useful for people that play cover songs; they can download GM MIDI files of commercial songs to u se as backing tracks.