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Harmonic Engine


  • • Create professional-sounding melodies & harmonies
  • • Map notes to different instruments and ranges
  • • Strummer creates interesting humanised chords

Video clips

Audio examples

Play like a pro. Use the AutoTheory Harmonic Engine to easily create chord progressions and melodies, whatever your musical background. The clear interface makes learning music theory easier by illustrating some of the ways harmony and melody work together.

Product details

The AutoTheory Harmonic Engine enables anyone, regardless of musical theory or keyboard training, to easily create professional-sounding melodies and harmonies.

Download the User Guide.

AutoTheory is featured in the book "Reason101 Visual Guide to the Reason Rack" by Robert Anselmi.

AutoTheory makes it easy to play in harmony. Simply choose a key and a scale and AutoTheory will map all relevant chords and notes to the keys of your keyboard. Connect it to one or more Reason instruments and it will transform the way you play.

Play full chords with just one finger. Experiment by modifying chords with the chord sliders and modifier keys. Adjust individual chord note voicings and transpose or remove any note to create a customised chord. Create your own scales or select one from the many provided. Use what sounds good to you.

AutoTheory automatically remaps notes to match your chords. Now you can easily improvise melodies that sound good. Maintain your hand in the same position while composing melodies over different keys, scales and chord configurations. Optionally lock specific chord tones to fixed white keys. Four mapping modes accommodate different levels of user experience.

All controls in AutoTheory can be automated for easy transitions anywhere in a song. This means you can change the key or scale in the middle of a song without moving your hands.

AutoTheory also provides a Strum effect that can be used to add drama to any chord. Subtle and extreme timing changes are easily applied and fully CV-controllable.

AutoTheory can control multiple instruments at once. One option sends the root note of chords to a dedicated bass instrument. Four chord and four melody channels provide independent control of velocity and octave for each connected instrument. This allows you to create a rich soundscape - all from a single sequencer lane or just your own hands.

CV inputs are provided, which are useful for driving AutoTheory with Arpeggiators and Pattern sequencers.

Check out the included Demo Songs that demonstrate how to use AutoTheory. A set of useful Combinators is also provided.

Concept by Mozaic. Engineered by Pitchblende, the engineers behind the Selig Leveler by Selig Audio and Ammo & Charlotte by Jiggery-Pokery.

Release History:

Version 1.0.5 - released February 2014

  • added 20 new and interesting Combinator patches by renowned ReFill creator, Navi Retlav.

Version 1.0.4 - released 25th October 2013

  • fixed issue with Melody gate output when using Seq CV input.
  • fixed issue with Note outputs not returning to zero when idle.

Version 1.0.3 - released 30th September 2013

  • fixed issue with black key mapping when Melody Lock is disabled.
  • fixed issue with Retrigger on Melody CV outputs 2-4.

Version 1.0.2 - released 14th August 2013

  • fixed issue with sustain pedal.
  • fixed issue with exact octave interval on Melody side.
  • added Chord-Based scales.

Version 1.0.1 - released 14th July 2013

  • prioritised chord modifier events to work correctly with quantisation.
  • added sustain pedal support.
  • fixed issue with melody-only CV input and low octaves.
  • fixed issue with zero-note chords in 'random' strummer mode.
  • fixed issue with single-note chords.

Version 1.0.0 - released 9th June 2013.

  • initial release.



Released: 2014-02-14
Version: 1.0.5