To install the Harp Gliss Trigger MIDI FX Script, unzip the downloaded package and move the file named 441K Harp Gliss Trigger.pst to the following folder. You will have to create the Scripter folder if it doesn’t already exist.

~/Music/Audio Music Apps/Plug-In Settings/Scripter

After installation, Harp Gliss Trigger can be found in MainStage 3’s Scripter MIDI FX plugin dropdown menu.


Harp Gliss Trigger is a MIDI FX script for Logic Pro X and MainStage 3 that can be used to generate a customized harp glissando in realtime.

Script Parameters

  • Trigger Note — The MIDI note that activates the script. The trigger note does not have to be the same as the start note.
  • Start Note — The first note of the glissando.
  • End Note — The last note of the glissando.
  • Tempo — The tempo of the glissando in beats per minute.
  • Gliss Duration — The length of the glissando in beats.
  • Start Velocity — The velocity at the start of the glissando.
  • End Velocity — The velocity at the end of the glissando.
  • Velocity Curve — Allows you to choose between a linear or logarithmic velocity curve.
  • Log Curve Control — Allows you to customize the distribution of notes over the gliss duration. A value LESS THAN 1 skews note distribution to the right. A value GREATER THAN 1 skews note distribution to the left. A value EQUAL TO 1 results in equal note distribution.
  • Harp Pedals — Allows you to choose the notes in the glissando.

Glissando Types

Harp Gliss Trigger allows you to generate four different types of glissandi — UP, DOWN, UP/DOWN, and DOWN/UP. To generate an UP/DOWN or DOWN/UP gliss, follow these instructions.

  1. Create one instance of Harp Gliss Trigger for the UP portion of the glissando.
  2. Create a second instance of Harp Gliss Trigger, and set the trigger note equal to the top note of the first instance.
  3. Log Curve Control is initialized at 1.00, but feel free to experiment with different values to achieve the desired feel.


If you’re using MainStage’s default EXS24 harp sound, be sure to change the polyphony setting to 64 voices for the best sounding result.


v1.1 — April 16, 2017

  • Changed harp pedal order.


  • Initial Release