Scaler 3 Plugin - No MIDI Output to DAW

Scaler 3 Support
1

Hello,

I’m seeing a problem where Scaler 3 does not send MIDI from its plugin UI back out to my external keyboard, even though Reaper routing and the keyboard itself are confirmed working. Below is a concise description of the issue and everything I’ve already checked.

Problem

  • Scaler 3 responds to my physical keyboard in its UI (notes light up when I play), but when I press notes inside the Scaler 3 UI the external keyboard does not sound.

  • The plugin UI shows notes, but no MIDI from Scaler’s UI appears in Reaper (I verified this with a MIDI logger placed immediately after Scaler in the FX chain).

My Reaper routing and hardware setup (what is working)

  • I have a dedicated MIDI track with Scaler inserted as an FX. That track’s MIDI Hardware Output (via the track IO / Route dialog) is set to my keyboard on MIDI Channel 1.

  • Short MIDI clips placed on the track and played back do trigger the keyboard, proving Reaper → keyboard routing and the keyboard’s reception on Channel 1 are working.

  • The keyboard itself transmits on MIDI Channel 1 and Reaper receives it; when I play the keyboard, the MIDI logger shows activity.
    What I’ve tested in an attempt to fix this

  • Inserted JS: MIDI Logger directly after Scaler in the FX chain.

  • Result: logger shows MIDI when I play my physical keyboard, but shows nothing when I press notes in Scaler’s UI.

  • Verified Scaler lane/output in the arrange window is set to Channel 1. I added MIDI items there and played them back; still no MIDI appears in the logger when triggered from the Scaler UI.

  • Tried both VST2 and VST3 builds of Scaler 3. Behavior is identical.

  • Scaler 2 now shows the same behaviour when loaded (so the issue affects both Scaler 2 and 3 in my setup).

  • Tried Scaler as an Input FX and as a Track FX; behaviour differs visually but neither mode results in Scaler UI MIDI reaching the keyboard.

  • Confirmed Reaper’s MIDI Hardware Output
    works by playing simple MIDI clips (keyboard plays).

  • Disabled other sends to avoid feedback loops while testing.

What this proves

  • Reaper → hardware MIDI path is functional (clips play the keyboard).

  • Scaler receives incoming MIDI from my keyboard (UI responds), but Scaler is not emitting MIDI into Reaper’s MIDI stream when notes are played from the plugin UI. The MIDI logger shows no plugin‑generated MIDI.
    What I cannot find / suspect

  • I cannot find any Scaler 3 setting labelled “MIDI Out”, “Send MIDI to Host”, or similar inside the plugin UI that would enable plugin → host MIDI.

  • I suspect either a Scaler setting that I’m missing, or a host/plugin handshake issue where Scaler’s UI note events are not being forwarded to Reaper’s MIDI stream.

Environment details

  • Reaper: 7.6.1
  • Scaler: 3.20, tested both VST2 and VST3 builds
  • Keyboard: receives on MIDI Channel 1; Reaper sends to it successfully from MIDI clips

Request Please can you advise:

  • Whether Scaler 3 (and Scaler 2) require an explicit “send MIDI to host” toggle that I’m missing, and where it is located.

  • Any Reaper preference or known VST3/VST2 nuance that would prevent plugin UI MIDI from being emitted to the host.

  • If you need any additional diagnostics (Reaper project, screenshots of the Scaler lane/output settings, or a short screen recording), I can provide them.

Thanks for your help — I’m sure I’m missing a small setting but I’ve run out of obvious options.

2

Hi, it’s a little strange, but I think I got something similar to work (never tried before). I actually have keyboard on external MIDI in and a Roland box on MIDI out, but that should make no difference to you.

  1. I set up Track 1 as “keyboard”. Click the red Record button. Right-click the Record button and select “Record: disable (input monitoring only”. (This is one aspect of Reaper that I find confusing.)
  2. I set up Track 2 as “SCALER”. I inserted Scaler3 as FX, as usual. I programmed a few chords into section C and enabled the link.
  3. Set the routing of Track 1 “keyboard” to have a MIDI send to Track 2 “SCALER”.
  4. Set the routing of Track 2 “SCALER” to have MIDI hardware output to external synth.

My results are:

  • Playing keys on external keyboard triggers the chords in Scaler.
  • Scaler chords are sent out to external synth.
  • If I put a MIDI clip on the SCALER track, the notes trigger the chords.
  • If I put a MIDI clip on the “keyboard” track, the notes also trigger the chords.

Maybe this helps?

1 Like
3

Thanks so much for the reply, appreciated. Sorry of it wasn’t clear.

I think understand everything you’ve said, but none the less had no joy.

I’ve uninstalled and reinstalled Reaper, scaler and any settings files and started from scratch. It all now works as expected, but I have no idea what was up. Thanks anyway.

4

I’m glad it’s working for you. I learned something from the exercise. (I’ve switched to Reaper fairly recently, after decades with another DAW - I’m still learning and making mistakes.)