Offtonic 19-TET

Version 0.1
Added 02 Aug 2012 (last updated 07 Mar 2014)

For use with Sibelius 6, Sibelius 7.1, Sibelius 7.5 and Sibelius 8.x

Allows playback of music in 19-tone equal temperament (19-TET). Very cool, huh? The 19-tone scale is not very different from our usual 12-tone scale. The diatonic scale can be reproduced very faithfully in 19-TET by interpreting a whole step as three 19-TET steps, and a half step as two. As a result, we can label the pitches as follows:

C C# Db D D# Eb E E#/Fb F F# Gb G G# Ab A A# Bb B B#/Cb

It's rather amazing that tonal music in 19-TET sounds so similar to tonal music in our usual 12-TET -- the only element that really breaks is enharmonic spellings, meaning that an augmented 6th is no longer equivalent to a minor 7th, for instance. We can take advantage of this fact by using our common 12-TET notation for 19-TET. No new symbols are necessary. Offtonic 19-TET adds a pitch bend message to each note in your selection, retuning your music to fit the 19-tone scale. Arbitrarily, C in 19-TET is tuned to the common C in 12-TET.

Interestingly, the 19-TET system allows some interesting sonorities. Thirds, both major and minor, are closer to their pure forms. The fifth is a tiny bit flat compared to the already narrow 12-TET fifth, but this is hardly noticeable. The augmented sixth sounds very much like a septimal minor seventh, the seventh overtone, which is a nice sonority. Leading tones are actually hampered by this system, as the diatonic half step of two 19-TET steps is wider than its 12-TET counterpart.

A major limitation of Offtonic 19-TET is that, by the nature of MIDI commands, it cannot retune chords, only single notes in each staff. Only one pitch bend command may be active at a time in a single staff, so if you need to retune multiple notes all sounding at once, they each need their own staff. This applies to chords, multiple voices, and even, more subtly, slurs, if they are set to increase a note's duration past 100%.

New in version 0.1.0:

  • Initial release
  • Removes all existing pitch bend messages from the selection and retunes the written notes to 19-tone equal temperament
  • Allows the user to specify the maximum pitch bend of the instrument
  • Includes a help dialog

Plug-in written by Mauro Braunstein.