Pure Harmony GPL
2/1, the octave, is the most harmonically consonant musical interval.
3/2, the perfect fifth, is the second most harmonically consonant musical interval.
4/3, the perfect fourth, is the third most harmonically consonant musical interval.
This is the basis for Pure Harmony.
Equal Temperament Tuning is equally out of tune in all 12 keys, it is a compromise tuning.
Just Intonation/Pythagorean Tuning is in tune, in 1 of 12 keys. Traditionally, and as is still the case for all non-electronically pitched instruments, 12 different instruments are needed and a mid-song key change would require quickly switching guitars or jumping to another piano. Taking 12 instruments with me to anywhere I wanted to practice or perform material in any 2 or more key signatures is simply not practical.
Nowadays, with advancements in electronics, software and MIDI, it is entirely possible to carry just one instrument with me, and have the choice at the push of a button or pedal to choose between 12TET Equal Temperament, Just Intonation tuning in any key, Pythagorean Tuning in any key, as well as customisable microtonal tuning systems that can be dialled in and saved.
When tuned electronically, pure harmonic tuning systems allow the opportunity to play perfectly in tune, in all 12 keys, simply pressing a button or footswitch at the moment that there is a key change/modulation in the song.
The Arduino platform has been chosen to develop software-based pure harmonic top octave generators. Arduino Uno R3 or ATMega328P with Arduino R3 bootloader is the hardware that we are going to use for our examples.
A number of electronic musical instruments can be built from this, electronic organs and keyboards that use top octave generator chips can be modified to play pure harmonic tunings by swapping them out for this circuit.
Stay tuned, code and schematics will follow…