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Substation relies on two fundamental concepts: polyrhythm and subharmonics.

About Polyrhythm

Let's start with polyrhythm. Polyrhythms are created when two or more rhythms overlap and play at once, creating a more complex, rhythmically interwoven phrase. These rhythms are still cyclic, but repeat over longer periods: for example, if divisions 3 and 4 are combined, the resultant polyrhythm will be 12 steps long.

In order to create polyrhythms, the PolyRhythm Sequencer combines up to four distinct clock divisions to create a new rhythm. Because all the clock dividers reference the same clock, they remain synced with the rest of your patch. For added complexity while performing, you can change the logic used to combine rhythms or alter the divisions on the fly.


About Subharmonics

Now that we've discussed polyrhythms, what are subharmonics? Before we talk about subharmonics, we first need to discuss overtones.

When physical instruments play notes, they generate additional tones at whole number multiples of the note's frequency. These are created by the way that sound waves move through physical materials. For example, a piano playing an A4 at 440 Hz will also create tones at 880 Hz, 1320 Hz, 1760 Hz etc. These are called overtones, or harmonics after the harmonic sequence in math.

The relative volume of these overtones is one of the main factors that determines the timbre of an instrument, and it is by manipulating overtones that filters can shape sounds. These overtones are especially welcome when playing chords, since they interact across notes and fill out the sound.

Subharmonics on the other hand, are created with whole number divisions of frequencies instead of multiples. They are difficult to create with physical instruments, but can be modelled electronically. Like overtones, subharmonics change the timbre of a sound, filling it out and making chords sound richer.

Substation uses subharmonics and overtones together to create rich, moving chords. It can also use subharmonics to self-modulate its oscillators, creating fractional multiples that sound wholly unique.

Overtone Interval Octave
×2 Unison Up +1
×3 Perfect Fifth Up +1
×4 Unison Up +2
×5 Major Third Up +2
×6 Perfect Fifth Up +2
×7 Subminor Seventh Up +2
×8 Unison Up +3
Subharmonic Interval Octave
÷2 Unison Down -1
÷3 Perfect Fifth Down -2
÷4 Unison Down -2
÷5 Major Third Down -2
÷6 Perfect Fifth Down -2
÷7 Subminor Seventh Down -2
÷8 Unison Down -3