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Setting Up External Audio Input in Reaper

The Audio input module can take its input from an external audio send from Reaper. This is especially useful if you compose music, and would like to make accompanying entrainment tracks that sync perfectly, even with tempo changes. Below are the steps you need to follow in Reaper to enable this feature:

  • Open a project in Reaper.
  • Load Lux onto an instrument channel and accept Reaper’s suggested track layout.
  • On the first Lux track, click on the IO button to open the routing dialog.
  • Set “Track Channels” to 10.



  • On the Reaper track you want to send to Lux, click on the I/O button to open the routing options for the track.
  • Under “Sends”, click “Add new send”.
  • Set the output to “Pre-Fader (Post-FX)”
  • On the audio track, turn down the volume to zero.
  • Back on the routing options window, below the horizontal fader, change the destination to “9/10”



  • On the 1st Lux, channel click on the FX button if the Lux GUI is not already visible.



  • On the Lux GUI window, click on the “2 in 8 out” button and make the grid look like the image below.


Now, you’re all set! When you set the Lux Audio Input module to “Ext. Audio”, any audio you pipe through that audio track in Reaper will be fed into the Audio Input module for further processing.



Signal Flow

People with engineering minds sometimes benefit from signal flow charts. Here is a diagram of the audio signal flow in Lux:



And here is a diagram of the data signal flow:


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