Ever wonder what that third port labeled MIDI THRU does?

If you look at the MIDI ports on your MIDI instrument, you may notice that there are three of them. An "in", "out" and a "thru." The thru port is not used as often as the other two. In most cases, you may never use it, but knowing how to may open up new creative doors for you.

The basic setup may look like this:

1. A computer is connected to a MIDI interface.

2. The MIDI interface is connected to a MIDI instrument by the "in" and "out" ports. Then a MIDI cable is connected the "thru" port on the MIDI instrument.

3. The other end of this MIDI cable will be connected to the "in" port of another MIDI instrument.

Now you have two MIDI instruments, one MIDI interface, and one computer in your MIDI setup.

Here's how it works.

When the computer plays a note, it sends a signal to the "in" port of the first keyboard. Then, instantaneously, is sends the same signal out the MIDI thru port on the first MIDI instrument and to the "in" port on the second MIDI instrument. Therefore, both MIDI instruments will play the same note on the same MIDI channel at the exact same time.

Here are the benefits.

  1. It allows you to combine instrument sounds for a thicker timbre. This layering effect allows you to create sound combinations not possible with one MIDI instrument alone.
  2. Let's say there is a specific instrument sound on your second MIDI instrument that you really want to use. You can use the thru port to control the second MIDI instrument to play that particular sound.


When doing this, there is one thing you will need to watch out for. Keep in mind that it is playing both MIDI instruments at the same time, therefore, you have to disable any channels on the first MIDI instrument so you only hear the second MIDI instruments sound.

For example, most MIDI keyboards can play up to 16 channels at one time. Let's say that on your second keyboard you really want to use the drum kit sounds. Drums are traditionally set to channel 10. So, you connect the two computers using the MIDI thru port on the first and the "in" port on the second. Then disable channel 10 on the FIRST keyboard. That way, you will only hear the sounds coming from the second keyboard.