TW #107 — Layman's Music Theory, part one (Zinc)

zinc, who has "absolutely no formal music training", writes the theory primer he wished existed: how to spell a triad from interval qualities. No further parts followed in the archive's TOC.

Key claims#

• A chord is two or more notes played together, most often three or more; a three-note chord is a triad; the root is the note the chord is built from (C in Cmaj, Cmin); the intervals from the root determine the chord type — triads come in four: major, minor, diminished, augmented.
• Scale degrees of C major: C D E F G A B C = 1 2 3 4 5 6 7 8, continuing D F A = 9 11 13; intervals from C: M2 M3 P4 P5 M6 M7 P8. "A C major contains a 3rd and a 5th."
• Interval qualities: M major, m minor, P perfect, o/dim diminished, +/aug augmented. All major triads have a M3 and a P5.
• Alteration rules: a major interval flattened by a half step becomes minor (M3 E → m3 Eb); a minor interval raised a half step becomes major (m6 Ab → M6 A); a minor or perfect interval made a half step smaller becomes diminished (P5 G → dim5 Gb, m7 Bb → dim7 A); a major or perfect interval made a half step larger becomes augmented (P4 F → aug4 F#, M9 → aug9).
• Table of intervals in whole steps (one step = two half steps): m2 ½ · M2 1 · aug2 1½ · m3 1½ · M3 2 · P4 2½ · aug4 3 · dim5 3 · P5 3½ · aug5 4 · m6 4 · M6 4½ · dim7 4½ · m7 5 · M7 5½ · P8 6 · m9 6½ · M9 7 · aug9 7½ · P11 8½ · aug11 9 · m13 10 · M13 10½. Some pairs are enharmonic equivalents (same sound, different spelling).
• Worked example: F#m = F# A C# — minor third = 1½ steps up (A), perfect fifth = 3½ steps (C#). "It works!"
• basehead told him "there's really no way to tell what chords will sound good together unless you just play them, so get a guitar or keyboard and see what sounds good."

Practical takeaways#

In semitones (steps × 2): m2 1 · M2 2 · m3 3 · M3 4 · P4 5 · aug4/dim5 6 · P5 7 · aug5/m6 8 · M6/dim7 9 · m7 10 · M7 11 · P8 12 · m9 13 · M9 14 · aug9 15 · P11 17 · aug11 18 · m13 20 · M13 21 — so major = 0 4 7, minor = 0 3 7, diminished = 0 3 6, augmented = 0 4 8 (see semitone-math and diatonic-chords). The alteration rules are the general recipe: any chord symbol is a stack of qualities counted from the root.

Notable quotes#

• "Until not too long ago, I thought I didn't need music theory. Unless I plan on composing 'experimental' techno for the rest of my life, though, I finally realized that I'd have to finally learn how to make different sounds work together."
• "If you have no idea how to figure out the notes in an Augmented chord, THIS ARTICLE IS FOR YOU."

Relevance#

The scene's own beginner explanation of interval quality and chord spelling; adds compound intervals (9, 11, 13) and the enharmonic note to semitone-math.

Pages touched#

semitone-math, diatonic-chords, chord-progressions, zinc (via notes), basehead (via notes).