A triad stacks root, third, and fifth of a scale degree; its quality is set by the semitone intervals

A triad is built by stacking scale degrees in thirds from a root: root + third + fifth. The interval pattern above the root sets the quality: major (0, +4, +7 semitones) is bright and resolved; minor (0, +3, +7) is sad and serious; diminished (0, +3, +6) is tense and unstable; augmented (0, +4, +8) is eerie. In theory-native engines (Strudel, Tidal, Sonic Pi, SuperCollider) these are invoked by name; in Glicol, ChucK, and Punctual they must be spelled as explicit frequency or MIDI offsets because there are no chord primitives. The semitone patterns are the framework-agnostic foundation for everything harmonic that follows.

Examples

chord('Am') = A + C + E (0,+3,+7 from A). chord('Adim') = A + C + Eb (0,+3,+6). In MIDI a major triad on A = 69, 73, 76.

Assessment

Give the semitone intervals for a minor triad and a diminished triad from the same root. Which is more tense, and which interval makes it so?