Since I’ve had this conversation several times lately, it’s clear to me that there’s not a lot of good info still out there on how to set up a basic MIDI rig! Working with MIDI is a ton of fun. The protocol is old-fashioned, and takes a little time to understand well. In my opinion, you’re better off spending the time understanding this than you are fighting with soundcards, latency, drivers, etc. Because MIDI actually works. :)

This guide should be a enough to get you out of most confusing situations, and will focus on the portions of the protocol that are implemented consistently and reliably.

The Absolute Basics of Working with MIDI:

1. MIDI is a serial protocol.

This means that control signals only flow ONE way! For this reason, all MIDI rigs are “Daisy-chained”.

Example of a chain in my studio:

MIDI OUT of MPC -> to MIDI IN of Yamaha DX200(CH5)

     MIDI OUT of Yamaha DX200 -> MIDI in of Elektron                                        Machinedrum(CH9)

          MIDI OUT of Elektron MachineDrum to MIDI IN of Korg Volca               Keys(CH1)
With this chain, control signals from my MPC are able to control the DX200, Machinedrum, and the Volca.
With this chain, control signals ALL devices are NOT sent back to the MPC.

So even though there’s a cable between the MPC and the DX200, I cannot turn a knob or play a note and send it back to the MPC. That cable sends data ONE way.

2. MIDI has 16 Channels.

In order to set up the chain I described in number 1, I had to do a few simple things that are necessary EVERY time you add new gear or change your setup:
A. I set each instrument to listen for control data on a unique channel – no overlaps!
B. I set the MPC to send data to each of these unique channels, specifically.

MIDI will not auto-negotiate channels, it won’t auto-negotiate ANYTHING. The MIDI data that’s destined for the Volca is ignored by the first two instruments- but ONLY because they were set to use a different channel.

MIDI sync/clock is effectively sent on all channels.

If you want your devices to sync with each other:

A.  Set up one to use “internal timing”

B.  Set the other to use “external timing”.(often referred to as master and slave) 

C. Connect the out of the “internal timing” device to the input of the “external timing device”

Note that your MIDI setup should only have ONE device as your MIDI master.  This device will provide tempo, start/stop, and clock data to your chain.  This keeps all devices in time with each other, starting and stopping together, etc.

3. How MIDI Passes THRU Instruments is Frustrating and Not Especially Consistent.

Expect to do a little fighting to totally understand how your specific instrument does this.
My Moog Little Phatty is connected to my MPC in AND out. This is technically a loop- but the Moog doesn’t complain and works as intended when in “MIDI Merge” mode.

My DX200 has a complete melt-down and locks up hard when plugged in this way, because this is a loop. The DX200 recieves signal which is forwards back to the MPC which sends it to the DX200.

5. Different Types of MIDI data are handled differently.

Take a look at this section if you want to understand what kind of data you’re trying to send to a device:

6. Lots of stuff made lately ONLY has a MIDI IN

. This sucks. Take a look at the example chain in number 1. Now imagine if I had a Volca Keys, and a Waldorf Blofeld. I couldn’t use them both together, because neither of them has a MIDI OUT!  They both have to be the final device in a MIDI chain.

Instruments like these are designed to be people’s first/only synth, or to be used in some weird case where you have a ton of MIDI outs on whatever is sequencing! So if you’re sitting at home with two devices right now, and reading this because you need to know how to connect two devices that only have a MIDI IN, you can stop now.  Also, stop buying stuff like this so that people will stop making it.

7.  The basics of MIDI have not changed since the protocol was created.

Your keyboard from 1983 and your keyboard from 2013 will play together nicely.  The beauty of this is that there’s a HUGE second-hand market of cheap, uncool keyboards that can sound great when used with an interesting sequence.  Tons of garage sale keyboards are ripe for this!