About MIDI connections

This article describes the function of the various MIDI connectors typically found on MIDI equipment. It also explains how you should make MIDI connections.


There are typically two or three MIDI connectors on MIDI equipment. These are:

  1. MIDI IN: This is where any incoming MIDI data is received by your MIDI instrument.
  2. MIDI OUT: This is where MIDI data is transmitted from the MIDI instrument.
  3. MIDI THRU: If there are three MIDI connectors, the MIDI THRU connector lets you "chain" MIDI instruments together. MIDI THRU simply retransmits whatever MIDI data is received at MIDI IN.

Making connections

When you make MIDI connections, you generally connect a MIDI output (OUT or THRU) to a MIDI IN. As usual, outputs are connected to inputs.

When you make MIDI connections, make sure you use proper MIDI cables. Do not use regular DIN cables as the wiring is different.

It is best to switch off your MIDI equipment before you make MIDI connections.

Possibly the simplest MIDI setup you can have is to connect two devices together, such as two keyboards, or a keyboard and a sound module. In either case, connect a MIDI cable from the MIDI OUT on the first keyboard to the MIDI IN on the second keyboard or the sound module. This allows you to play on the first keyboard and whatever you play will also play on the second keyboard. When you do this, the first keyboard is sometimes referred to as the "master" and the second, the "slave".

When you want to connect a sequencer or computer, connect the MIDI OUT from the MIDI keyboard to the MIDI IN of the computer or sequencer, then connect the MIDI OUT of the computer or sequencer to the MIDI IN on the keyboard. At this point, it looks as if we have a loop, so it is important that you use MIDI IN and OUT, not IN and THRU. If your keyboard only has two MIDI sockets (IN and OUT/THRU), make sure its THRU function is turned off.

One problem commonly experienced when using a sequencer is that of "doubled" notes. When you play, the notes sound slightly strangely. This can happen if the keyboard plays what you play and also the sequencer echoes back what it receives and the keyboard then plays what it receives from MIDI IN. Many keyboards have a function called "Local". When you play the keyboard normally, you want notes you play to sound. However, when you use a sequencer, you want the sequencer to play the notes, not the local keyboard. So, when using a sequencer, typically, you should either turn on the sequencer's MIDI THRU function and turn off the keyboard's Local function; or turn off the sequencer's MIDI THRU function and leave the keyboard's Local function turned on (the first of these is preferred)

We will consider just one more setup: a keyboard, sequencer and sound module. First, make MIDI connection as described above for connecting the sequencer. But then, connect an additional MIDI cable from the MIDI THRU from the keyboard to the MIDI IN of the sound module. Now, whenever the sequencer sends MIDI data, it will be played by both the keyboard and the sound module.

In this setup, if you want the keyboard to play certain parts and the sound module to play others, you will have to set each instrument to respond to only certain MIDI channels. Consult the manuals for details of how this is done. The alternative, if you can, would be to use two MIDI OUT connections from the sequencer (or computer).


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