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Understanding MIDI Interfaces
The Role of the MIDI Interface, with Real World Examples
Tweak's MIDI system as seen by Mac OSX. Note how the system "sees" the MIDI ports on my Unitor 8 system, 828mk2, Remote SL. All of those ins and outs are simultaneously active and ready for use in my sequencers.
Building a MIDI rig inside your computer-based recording studio? Then you know you need a MIDI interface of some sort. The more midi devices you have the more a separate MIDI interface is necessary. Sure, you can start off with using the typically single port on your audio interface. Maybe you can get away with that and the USB midi interface built into your keyboard controller. Maybe not. Lets take a look.
Do I even need a MIDI interface?
Note that if you are exclusively dealing with software synths you don't need an dedicated MIDI interface. A single MIDI port will do fine, as all you have to do is connect a keyboard controller. On some controllers with USB outputs, this interface is built-in). Inside the software you are using, the softsynth will build it's own virtual midi channels as needed. It's when you are using hardware MIDI devices that a MIDI interface is needed. The more gear you have the more ports you need. So you decide how much MIDI gear you think you will get? There is a lot of different gear that uses MIDI. Its not just keyboards. MIDI sound modules require MIDI connections. Effect processors, such as reverbs, delays, harmonizers, guitar pedal rigs, use MIDI to dump data and switch programs. Multi-track recorders use MIDI for MIDI Time Code and MIDI Machine Code. Control Surfaces usually require a whole 16 channels in and out in order to send and receive data from your sequencer. You can find 1x1, 2x2, 4x4 and 8x8 MIDI interfaces commonly available. How many ports do you need? Read on.
Why get a dedicated MIDI Interface?
"Whoa dude" you might think, that you will never need 128 MIDI channels. But it is rather surprising when one gets into MIDI gear how quickly these channels get used up. Want a Mackie Control (or automated digital mixer or control surface)? Count off 16 channels used. A multitimbral keyboard/master controller? 16 more used; 32 gone now. A emu proteus 2000 module (which has 2 MIDI in ports)? There goes another 32, only 64 left. Hardware sampler? 48 left. Say you bought some vintage stuff on ebay, maybe a Juno, a TX802, you are now down to 16. Hook up a few FX boxes and you only have a few channels left.
To be sure, you can be as stingy as you want with MIDI channels if you take the time to configure your synth to only respond to a few channels for each piece. For example I can turn off 30 channels on my Proteus 2000 and only use 2 if I want, and I could chain up 16 modules to a single midi port if I wanted to. But I don't want to. I want the freedom to use all 16 channels of my triton in every song and all 32 of my proteus 2000. Why? When you are making a song its easier not to use program change commands. You just set the channel to a program and it stays there. You can use a whole channel just for one little hit inside a song. Building up a string section on a module might take 5 or 6 MIDI channels and programs. Creating a drum track might mean using one channel for each drum instead of using a preset one channel kit. So why do we get a large MIDI interface? Call it compositional freedom if you will.
MIDI is old tech. Even when it was introduced in 1983, people where already complaining that the bandwidth of the MIDI port was too small; that it could not effectively handle a full 16 channels of notes. The solution was to add more ports, so one could "spread out the load" to different ports and different modules.
I have both a Unitor8 and an AMT8. They can be ganged together with a single cable, turning the 8x8 into a 16x16. You can gang up to 8 of these MIDI interfaces together. Ok I can't resist. 128x8 channels is 1,024 MIDI channels. Enough? It better be, cause you can't do more than this without adding more computers. I've had my interfaces over 3 years and they work really well. I've used them on PCs, a Mac G5 and a G4 powerbook, and I've used them connected to the serial port and the USB port. Both methods are fast and reliable.
But not everyone needs that kind of power. So how many ports/channels do you need? Kind of depends on your style. If you don't mind daisy chaining midi devices and turning channels off on your multi-timbral devices, a simple m-audio MIDIsport 2x2 will do just fine for most people. That would give you 32 channels on 2 ports. That means only 2 devices can go into the computer, but as many as 32 could go out, given that each device only has 1 channel. Of course, all multitimbral synths have many channels so that might not make sense for you.
Real World MIDI configurations
Remember every MIDI port (one midi in connector and one midi out connector on an interface) carries 16 channels of data. However, you physically can connect only 1 device to a midi input. (The only exception here is if you have a MIDI merge box that will combine several midi cables to one midi stream).
To connect multiple devices to a MIDI OUT port you connect the MIDI THRU on the 1st device to the MIDI IN on the second device. The second device's MIDI THRU goes to the MIDI IN of the third device, and so on. Do not confuse midi ports with the jacks on your keyboard--those are not ports. Ports are on the midi interface as they connect directly to the computer usually through USB. So you got that? The MIDI interface connects the keyboard to and from the computer. Exception: Note that some controllers have USB ports that connect directly to the computer. Those may be considered as a built in 1x1 MIDI interface.
Understanding this is hard at first. So I will give you several examples:
5 common MIDI Hookup examples
Lets say you had a Triton (16ch) , an electribe EA (2 ch), 3 midi FX boxes (1ch ea) and a Mackie Control (16 channels). Which interface do you need? Can you figure it out?
In this situation you need at minimum a 3x3 midi interface. First lets go TO the interface: Triton goes to MIDI IN 1, Mackie goes to MIDI IN 2 and the Electribe goes to MIDI IN 3. The FX boxes do not need to send data to the computer to work.
Now, lets go OUT of the MIDI interface. Out 1 goes to the Triton; Out two goes to the Mackie; Out 3 goes to the FX box 1; the THRU on FX box 1 goes to the IN of FX box 2; the THRU of FX Box 2 goes to the IN of FX box 3; the THRU of FX box 3 goes to the Electribe.
Of course you won't find many 3x3 interfaces so go for a 4x4.
You have a USB controller keyboard and will be running only soft synths. Do you need an interface? Answer: No.
You have an audio interface with 4 midi ins and outs. Do you need an interface? Answer: No. The MIDI ins and outs connect directly to the computer (through Firewire typically) and you don't need anything else, unless you get more than 4 controllers.
You are a synth collector and have 16 synths and modules. You want all of them to send and receive because you are working a lot with patches with sysex data. What is the minimum you can get by with? If you use only 1 channel on each you can get by with a 1x1 and a 16ch midi merge box, if you can find one. Ideally you would get 2 8x8's to make this a simpler operation. That way each synth has its own in and out, with no changing and merging. Or you could get one 8x8 and use an 8 ch merge box.
You have one keyboard and 4 modules and have a 1x1 midi interface on your soundcard built in. How to hook this up?
I would put the keyboard and your 3 best modules on a 4x4 MIDI interface and use the soundcard midi interface for your least used module
You only have a 1x1 interface on the soundcard but have 2 controllers. How to get them both in to the computer simultaneously? You get a 2-to-1 MIDI merge box or break down and get a 2x2 midi interface (recommended).
Ok, its time for Questions and Answers
Questions from the audience:
Q) Is USB OK for MIDI interfaces? I heard it was bad.
A) USB is fine for MIDI. Its Audio that is troublesome with USB sometimes due to the narrow bandwidth of the USB 1.1 spec. However, midi data is very small and efficient code compared to audio and a single USB cable can handle up to eight 8x8 midi interfaces if the manufacturer allows such connection.
Q) Is there a such thing as a high quality MIDI cable? Will it make me sound better?
A) MIDI cables only have a negative effect on sound when they break. And that happens rarely, and only to the absolute cheapest garbage cables. Do you know that my MIDI cables have lasted longer than any piece of equipment I own? Its true! The main thing is to have enough cables for your gear, ideally at the proper lengths. But don't worry, they still work if too long.
Q) How Long can they Be?
A) 50 feet
Q) What is SysEx?
A) SysEx is short for System Exclusive Code, which is MIDI data that is designed to control specific models of gear. Synth patches are usually in the form a SysEx and they can be shuttled to and from a computer for editing in synth editor applications.
I hope this has helped you understand how the MIDI interface fits into the scheme of your computer-based rig. It can be tricky to understand at first so if you have questions come over the studio-central configuring your rig forum and ask. We have the answers.
"The soul of music slumbers in the shell
Samuel Rogers (17631855)
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