19TET

19TET, or 19-tone equal temperament, is a system of dividing the octave into 19 equal steps. The octave ratio is 2:1, and each step equals 1200/19 ≈ 63.16 cents. Like other equal temperaments, 19TET keeps octaves, fifths, and other intervals consistently sized across the scale, but it uses a different step size than the more common 12-tone equal temperament.

In practical terms, the scale provides 19 evenly spaced pitch classes within each octave. The closest approximations to familiar just intervals are asymmetric because the division is not aligned with 3/2 or 5/4 exactly. For example, a fifth above the tonic is best approximated by 11 steps, about 694.7 cents, near the just 3/2 (701.955 cents). A major third is most closely matched by 6 steps, about 378.95 cents, near the just 5/4 (386.31 cents). Other intervals diverge more from their just counterparts, reflecting the trade-offs of this temperament.

Notation and instrument setup for 19TET typically involve a keyboard or fretboard configured to 19 equally spaced pitch classes per octave, with accidentals representing the microtonal steps between the standard letter names. Performers may retune electronic instruments or use specialized keyboards and software to realize the system.

Usage and reception: 19TET has been explored in microtonal and experimental music as a compromise between 12TET’s simplicity and the needs of more precise just intonation. It appears in academic discussions, tuning experiments, and some synthesizer and software environments that support alternative ET systems.