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REAPER Setup Guide

How to use VEX MIDI EXPRESSION in REAPER to transform your MIDI controller data.

Flexible FX Chain

Great news! REAPER has one of the most flexible plugin architectures of any DAW. VEX can be placed directly before your instrument in the FX chain, and MIDI flows through automatically. No complex routing required!

How It Works

In REAPER, FX are processed top to bottom in the FX chain. Place VEX above your instrument:

FX Chain (top to bottom):
   |
   v
[VEX MIDI EXPRESSION]  <- MIDI Effect
   |
   v
[Virtual Instrument]   <- Synth/Sampler
   |
   v
[Audio Effects...]     <- Optional
   |
   v
Track Output

Setup Guide

Step 1: Create a Track

  1. Right-click in the track area and select Insert new track (or press Cmd+T / Ctrl+T)
  2. Name the track by double-clicking the track name

Step 2: Open the FX Chain

  1. Click the FX button on the track (or press F on the selected track)
  2. The FX browser window opens

Step 3: Add VEX to the FX Chain

  1. In the FX browser, search for "VEX"
  2. Find VEX MIDI EXPRESSION under:
    • VST3 (Windows/Mac/Linux)
    • or AU / Audio Units (Mac only)
  3. Double-click to add it to the FX chain

Step 4: Add Your Instrument

  1. Click Add in the FX chain window (or the + button)
  2. Search for your instrument (e.g., "Serum", "Vital", "ReaSynth")
  3. Double-click to add it below VEX

Your FX chain should now show:

1. VEX MIDI EXPRESSION
2. [Your Instrument]

Tip: You can drag plugins up/down to reorder them. VEX must be above the instrument.

Step 5: Configure VEX

  1. Click on VEX in the FX chain to open its window
  2. Add a mapping for your CC number:
    • Click + Add Mapping
    • Set the CC number (e.g., CC1 for Mod Wheel, CC74 for Filter)
    • Choose a transform type (Bouncy, Spring, Warp, etc.)
  3. Move your MIDI controller to verify input is received

Step 6: Set Up MIDI Input

  1. Right-click the track's record arm button (red circle)
  2. Select Input: MIDI → [Your MIDI Controller] → All Channels
  3. Arm the track for recording (click the record arm button)

Step 7: Play!

Play your MIDI controller - the instrument receives transformed MIDI data through VEX!

Important: Use Track FX, Not Input FX

REAPER has two FX locations:

  • Track FX (regular FX button) - Use this for VEX
  • Input FX (on the record input) - Avoid for CC processing

Warning: The Input FX chain filters out MIDI CC data in some configurations. Always place VEX in the regular Track FX chain.

MIDI Pass-Through (If Needed)

Most plugins pass MIDI through automatically. If your instrument isn't receiving MIDI from VEX:

  1. In the FX chain, click the I/O button (or "2 in 2 out") on VEX
  2. In the pin connector window, look for MIDI Output
  3. Right-click and select MIDI Output → Merge with MIDI bus

Using Multiple VEX Instances

You can stack multiple VEX instances in the same FX chain:

1. VEX MIDI EXPRESSION (CC1 mapping)
2. VEX MIDI EXPRESSION (CC74 mapping)
3. [Your Instrument]

Each VEX processes different CCs independently. Alternatively, use a single VEX with multiple mappings.

Troubleshooting

VEX doesn't receive MIDI input

  • Check the track's MIDI input is set to your controller
  • Ensure the track is armed for recording
  • Verify your controller is sending the correct CC number
  • Check REAPER Preferences → MIDI Devices - ensure your controller is enabled

Instrument doesn't respond to transformed MIDI

  • Make sure VEX is above the instrument in the FX chain
  • Check VEX's MIDI output routing (see "MIDI Pass-Through" section)
  • Verify the instrument responds to the CC number you're transforming
  • Look at VEX's output meter - it should show transformed values

Latency issues

  • VEX runs at sub-10ms latency
  • If experiencing delay, reduce REAPER's audio buffer size in Preferences → Audio → Device
  • Use 128-256 samples for lowest latency during performance

Saving FX Chains

Save your VEX + instrument setup for reuse:

  1. In the FX chain window, click the + menu (or right-click)
  2. Select FX Chains → Save FX chain
  3. Name it (e.g., "VEX Bouncy + Serum")

To load later, go to FX Chains in the browser and double-click your saved chain.

Need help? Contact us at support@extrasensory.studio