How to Split Stereo Tracks to Dual Mono in REAPER

Sometimes, when you receive a stereo recorded file, you just want to process each channel of the recording differently. There are several ways to accomplish this in REAPER, in this article I’ll be showing two ways of doing it. Feel free to use the one that better suits your workflow and needs depending on the situation, so let’s get right to it.

On a particular occasion, I received a multitrack recording for mixing, and in this multitrack, the Rhythmic electric guitars were stereo files. However, that’s because the first channel of the audio item is the processed guitar that was recorded through an amplifier with distortion, and the second channel is the raw DI recording. Thus, I wanted to separate these files so I could compare and decide which one I would be working with.

multitrack recording stereo files REAPER

Exploding the Audio into Mono Files

The simplest way of doing this is by exploding the item into one-channel files. So first, is right clicking the item and selecting the option item processing, then, in the sub menu, click the option Explode multichannel audio or MIDI to new one-channel items.

explode audio into mono REAPER

REAPER will then convert the current track into a folder track, mute the selected item, and create one-channel items for each of the original item channels (placed into new child tracks). You now have the option of processing each child track or item separate from each other.

child tracks REAPER

You can also search it in the action list, type Explode audio items and double click the action name. If you find yourself needing this action often with your workflow, consider creating a shortcut or setting it up as a button in a toolbar.

explode audio items REAPER

Take Channel Mode

Exploding audio into one-channel items writes new files into your drive, so if you don’t want this to happen, you may like this alternative better. This method takes advantage of the fact that REAPER tracks don’t have a set number of channels, so you can have mono and stereo files sharing the same track.

First, right click the track you’re working on and select the option Duplicate tracks.

duplicate tracks REAPER

Now, having the two copies of the item in different tracks, right click on the first item, go to item settings, and select the option Take channel mode: Mono (Left).

channel mode mono REAPER

Next, do the same for the second copy of the item but this time select Take channel mode: Mono (Right).

channel mode mono right REAPER

REAPER will display and playback each corresponding channel of the audio item without creating new files

Common Use Cases

  • When you want to process each side of a stereo Overhead or Room recording separately.
  • When you have one file that contains a recording with multiple microphones.
  • When you receive a multitrack recording of a drum performance in one file
  • When you have a mono recording that was captured with a device that only writes stereo files and the second channel only has noise.

Consolidating Two Mono Items Into One Stereo File

Now, after separating the distorted guitars from their DI tracks, I decided that I wanted to use the distorted guitar tracks, but I want to treat them as one pair of guitars. So, I’ll have to convert them into a stereo file.

The most intuitive way of converting the two mono recordings to a stereo file is rendering a new track that receives these two panned tracks.

So first, pan hard left and hard right each track.

panning tracks REAPER

Then, create a new track that will be a folder track for the two tracks and set the folder up by dragging the audio tracks to the folder.

folder track REAPER

After that, create a time selection that will represent the portion of the track that you want to render into a stereo track. Leave the folder track selected

create time selection REAPER

Lastly, open the action list by typing ?, search the action render selected area of tracks to stereo stem tracks and double click it.

render selected area of tracks REAPER

This action will render the pre-fader output of the folder track into a stereo wav file, then mute it and place the new file into a new track.

pre fader output to stereo WAV REAPER

Conclusion

These tools are one of the most essential ways of managing multichannel files and item channels inside REAPER. Now, since REAPER doesn’t have mono or stereo tracks, the ones that carry the information if something is mono or stereo are the items, which makes some workflows slightly slower, but opens up a whole new world of possibilities for others! I dare you to give these features a go the next time you find yourself working with stereo files, have fun!