Adding a MIDI controller to Reaper

This is a recent addition to my home studio. The Korg nanoKontrol2 is a MIDI control surface that connects to the PC using a USB cable. Its an inexpensive versatile piece of kit.

It has the usual transport controls on the left hand side and 8 fader modules to the right. Each fader module has the slider fader, a rotary pot and three switches “S” “M” and “R”. It can be mapped directly to the reaper Transport controls and Mixer, but I intended to use it differently.

The kit comes with a comprehensive PC application that allows you to assign any MIDI control change number to the hardware elements. I used the defaults and this is programmed by applying USB power whilst the “Cycle” and “Set Marker” buttons are pressed.

When the unit is plugged in, it must be enabled for input on the MIDI devices dialog.


Reaper has a very powerful “Actions” feature. It is possible to map the internal system functions (e.g. start recording) to a PC key press or a hardware element on the controller itself. Furthermore, it is possible to chain several system functions as a single custom action. (Macro) Reaper actions have a “Learn” feature whereby you select the action you want and then press a PC key or twiddle a pot on the nanoKontrol2 and a link is made automatically.


What I have done is to map the Transport controls directly to the Reaper transport controls. I have then assigned the fader modules as follows:-

Fader Module 0 (first far left) — Master track

“S” : Toggle the mixer window on the PC screen

“M” : Insert a stretch marker

“R” : Invoke external MIDI editor(Cakewalk) for current track

Fader: Adjust Master volume

Fader Module 1 (far left) — Selected track

“S” : Set automation mode to Write for the selected track

“M” : Set automation mode to Read for the selected track

“R” : Set automation mode to Write for the selected track, start Play to record automation.

Fader: Adjust selected track volume

Fader Module 6 (far right) — Instrument expression

Fader: Adjust selected track expression on Spitfire VSTi

Fader Module 7 (last far right) — Instrument quality

Fader: Adjust selected track quality on Spitfire VSTi


The default mode for the switches is to issue two MIDI CC messages, one for the key press and one for the key release. There is another toggle  mode that issues a single CC message for a key press/release and toggles the state. It also switches a red LED on and off. These switch modes can be independently programmed.

Unfortunately, REAPER does not seem to allow the Learn mode to distinguish between key press and key release messages. Well it kinda does by setting the learn range to -65..+65 for a switch, but it doesn’t always work.