The Problem With Fixed Tuning
Every DAW you've ever used treats a note as a fixed point on a grid. Middle C is always 261.63 Hz. An A above it is always 440 Hz. These frequencies come from 12-tone equal temperament (12-TET) — a system that divides the octave into 12 equally spaced semitones.
It's a compromise. A mathematically elegant one, but a compromise nonetheless. A perfect fifth in 12-TET is 700 cents. A pure perfect fifth — the one the overtone series produces — is 701.96 cents. A major third is 400 cents in 12-TET, but 386.31 cents pure. You can hear the difference: 12-TET thirds beat audibly, a wavering interference pattern between partials that don't quite align.
For 400 years, we've accepted this as the cost of being able to play in any key.
Just Intonation: The Old Answer
Just intonation (JI) uses pure frequency ratios instead of equal divisions. A perfect fifth is exactly 3:2. A major third is exactly 5:4. These intervals produce zero beating — the partials align perfectly and the sound fuses into a single, resonant whole.
The problem? JI doesn't modulate. A scale tuned for C major has wolf intervals in other keys. The same note D needs to be 9/8 in one chord and 10/9 in another — but traditional JI gives it one frequency. Play a I–vi–ii–V–I progression in pure JI and the pitch drifts flat by a syntonic comma (~21.5 cents) every cycle. This is the comma pump, and it's why JI never replaced equal temperament in practice.
Dynamic Harmony: Notes as Relationships
Arbit takes a different approach. Instead of choosing between fixed equal temperament and fixed just intonation scales, it makes every note's frequency dynamic — determined by its harmonic relationship to other notes.
Here's how it works:
- Link any two notes as master and slave. The slave's frequency becomes a pure ratio of the master's — 3:2 for a fifth, 5:4 for a major third, 7:4 for a harmonic seventh.
- Chain links into hierarchies. A links to B, B links to C. Move C and the entire structure cascades, preserving every relationship.
- The same pitch class can have different frequencies in different chords. D in a V chord (linked at 9:8) and D in a ii chord (linked at 10/9) are separate note objects with separate frequencies.
This eliminates the comma pump entirely. There's no shared pitch to drift. Each chord defines its own tuning context, and modulation is free — move one anchor, everything follows.
Beyond Purity: The Full Tension Spectrum
Dynamic harmony isn't just about making things sound "pure." It gives you the widest possible range of harmonic tension. Link a note at 5:4 and hear absolute consonance — zero beating, pure fusion. Link it to a different anchor and hear the collision between harmonic contexts: intentional beating patterns, intervals the ear has no name for.
This is the space between Balinese gamelan (where paired instruments are deliberately detuned to create shimmering ombak) and Renaissance polyphony (where voices lock into pure triads). Dynamic harmony lets you move seamlessly between these extremes.
Try It
Arbit is a VST3/CLAP plugin and standalone app that puts dynamic harmony into a piano roll. Shift-click to link, double-click to cycle through harmonics H1–H32, and hear the difference immediately. It's in beta now — learn more.