The Diatonic Converter is an adapter for projects such as the Infinite Melody and Gated Comparator, constricting their outputs to the notes of a major or minor diatonic scale instead of the chromatic scale. A single control line selects between major and minor. Three control lines select the note in the scale, and three more select the octave.

The key in which the notes are played is determined by sending the appropriate voltage into the unit's mix input, or mixing the output of the unit with other voltage sources externally.

Of course a 1 volt per octave VCO is required to convert the control voltage output of this module into an actual pitch.

Note that this module is NOT a quantizer. It works with a digital input, NOT an analog one.

Some ideas on how to use this module:

The Diatonic Converter can be integrated into modules such as those mentioned above, or by using the integral gate interface, can be controlled by other events in the synthesizer, such as keyboard gate signals, LFOs etc.

Of note is that if the note and octave control lines were connected directly to a binary counter in ascending order, there would be two of the root note of the scale present at each octave, except for the first and last. This is because the scale as generated contains eight notes per octave, starting with "C" and ending with "C1", so "C1" of the first octave played would be followed immediately by "C" of the second octave played, though an octave higher than its first sounding.

While this may seem awkward, when fed from random generators, the doubled weighting of the root note actually is an advantage, reinforcing the notion of the particular key in which the melody is playing.

Like the previous version, there are optional integral gate converters to allow the digital inputs used by the diatonic converter core to be wired to sockets on a front panel. This time there are seven, allowing all inputs to be used.

A span input allows the span between notes to be adjusted, for microtonal or non-scaled applications.

A little on how it works:

The schematic of the core of the Diatonic Converter.

The integral gate converters.