Tritone Substitutions

Original Article ↗ Hacker News Discussion ↗

Overall reaction to the article

  • Many readers enjoyed seeing music theory on HN and liked the geometric/intuitive framing of tritone substitutions.
  • Some found one diagram (rotation / circle) visually confusing, especially due to color choices and unclear relation to circle-of-fifths vs chromatic circle.
  • A few felt the explanation of “rotate 180°” could be clearer about what, exactly, is being rotated.

Tritone substitutions: function and history

  • Discussion of jazz usage: ii–V–I becoming ii–♭II–I, with the tritone sub giving a chromatic bass line and rich dominant color.
  • Emphasis that in jazz comping, 3rd and 7th (“guide tones”) define function; bass choice often determines whether a tritone sub is actually heard.
  • Some argue early “tritone-like” moves in Baroque/Classical works (e.g., Scarlatti) are not true tritone substitutions, but contrapuntal/voice-leading phenomena that only resemble modern jazz harmony.
  • Debate over whether it is valid to apply jazz harmonic concepts retroactively to older music; consensus: fine as a personal tool, but historically questionable for scholarly analysis.

Consonance, dissonance, and tuning

  • Disagreement over how “very dissonant” a tritone is.
    • One camp: tritone is highly dissonant in simple-ratio / just-intonation terms.
    • Another: minor seconds are more dissonant; tritone is only “moderately” tense and culturally framed.
  • Several argue consonance/dissonance is contextual and learned, not absolute; blues, other cultures, and equal temperament shift perceptions.
  • Some microtonal / just-intonation comments note multiple distinct tritones (7/5 vs 10/7) and intonation tradeoffs in tritone subs.

Notation and enharmonics

  • Strong push to spell tritone-sub chords correctly (e.g., D♭7 rather than C#7 for a G7 sub), maintaining stacked thirds and functionally sensible Roman numerals (e.g., ♭II7 vs V7/♯IV).
  • Discussion of when to choose sharps vs flats: direction of motion, key signature, chord spelling, and instrument ergonomics (e.g., harp, accordion).

Music theory vs counterpoint, history, and culture

  • Repeated reminder that much pre-19th-century music was conceived in terms of counterpoint, intervals, partimento, and melodic reduction, not chord labels.
  • Several recommend counterpoint and partimento resources and mention Schenkerian analysis, noting both its analytical influence and its problematic ideological baggage.
  • Some criticize treating “functional harmony” as universal; stress that theory is descriptive, culture-specific, and often retrofitted to existing practice.

Music theory, coding, and learning

  • Many coders ask how music theory “feels” to learn compared to programming.
  • Common answer:
    • Composition and improvisation ≈ “writing” and “speaking”;
    • Theory is more like grammar and patterns than strict algorithms.
  • Strong theme: the real goal is ear training and internalization so theory disappears in performance.
  • Several lament that instrumental education (especially for single-line instruments) often omits harmonic understanding, making playing feel like “just work.”