Turn MIDI Files Into Multitrack Music with Reaper

Turn MIDI Files into Multitrack Music with Reaper

A little known feature of the Reaper DAW software is its ability to automatically split MIDI music files (of which there are thousands for free on the Internet) into multiple tracks to which you can assign instruments and then mix and render with effects.

In this article we will teach you how to add MIDI files to Reaper and how to orchestrate and mix a final product, in this case a fine example of Classical Chipmusic.


MIDI is an outdated format, at least as a way of storing musical performances, and online music has moved on quite a lot since the ’90s. Most browsers used to support MIDI files natively but now most of them don’t, which is a shame for those online music sites which host large amounts of MIDI files like the one in our example. But formats move on and times change.

For example, the only version of Quicktime which supports the old general MIDI format these days is Quicktime 7 which you can still get and should have in your toolkit anyway to play old file types.

But what about making MIDI files into music? Is there a way to use these old forgotten pieces of music – classical, rock and game music – to make our own little tiny musical masterpieces?

Reaper to the Rescue

Although it’s not well documented, Reaper does a pretty decent job, better than most DAW software, of turning MIDI into music.

It’s easy, and let’s prove it. Go here and download a MIDI file. We are going to turn it into chipmusic, a spot of Bach, perhaps the Brandenburg Concerto 3. Also, to be our instrument, go and download a copy of the wonderful and free Magical 8bit Plug as the chipmusic instrument you are going to use.

Drag and Drop

To get the MIDI file into Reaper, just drag and drop it into a track like you would with a WAV file. You will be prompted and asked what you want to do.


Sometimes you might want separate tracks, and sometimes you will want all the tracks in one to play them on the same instrument. Let’s do the second one first. Uncheck the first checkbox, if it isn’t already, and load them all into one track. You will be asked to confirm you want to do this.


Once your MIDI data and tempo are imported, you need to assign an instrument. Click the FX button on the track and select Magical 8bit Plug.


Reduce the volume to around 0.19, change to square wave and trim the SusLevel to around 0.12 to avoid blowing your speakers or headphones out before you play.


Change the sound to suit your taste. We added a little Delay of around 0.45 to make it a tiny bit more musical and less staccato. Now play the track. It’s good, but wouldn’t it be better to have separate instruments?

Multitrack Music

If at the import stage you decide to import separate tracks, then you need to assign an instrument to each of the tracks.


Click the FX button on each track in turn and add the Magical 8Bit Plug instrument, and adjust the tone, length and sound of the notes while paying back the track.

Using the same Magical 8bit plug, you can use square, triangle or noise and two types of pulse. It’s a very basic synth designed for 8bit music, but you can get a very diverse range of sounds.

Here’s a tip: Pay attention to the name of each track; sometimes the author has taken the trouble to name each track with the name of the instrument for which it was meant. This means you can tweak the sound to imitate a violin, guitar or bass sound. Some sounds are long and some are short, some are tinny and some are full.


If you use a noise sound, you can add a drum beat to your tune. Make sure you reduce the sustain and delay to make the sound short, percussive and staccato.

Finally, mix or balance the sounds together. Remember the same or similar sounds playing together will be louder than different sounds. Slide the faders to get a good balance of sound throughout the entire track. Then pan each sound around the stereo picture using the little pan knob at the top of each track to position the sound in the mental image of the room. Shut your eyes and just listen to the mix and move things around.


Add a bit of reverb (like the convolution reverbs we talked about in a previous article), and you are done. To find more MIDI files to turn into music, Google “MIDI files” and explore the world of free MIDI music.


If you have any ideas or comments about making music with MIDI files, please let us know in the comments below.

Phil South
Phil South

Phil South has been writing about tech subjects for over 30 years. Starting out with Your Sinclair magazine in the 80s, and then MacUser and Computer Shopper. He's designed user interfaces for groundbreaking music software, been the technical editor on film making and visual effects books for Elsevier, and helped create the MTE YouTube Channel. He lives and works in South Wales, UK.

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