The power chord and distortion
The power chord (C5) consists of the root and fifth (C – G), often with the octave (C – G – C). It has no third: it is neither major nor minor. The reason is acoustic: with heavy distortion, intervals generate intermodulation products (sum and difference frequencies). For a perfect fifth (3:2 ratio) the difference frequency is half the root, that is, an octave below: it reinforces the bass and sounds “powerful.” With a major third (about 5:4, and slightly sharp in equal temperament) the higher-order products pile up close to one another and, because of the tempered tuning, beat: the sound becomes dirty and muddled. This is why in metal thirds are used mainly in clean arpeggios, lead guitar harmonies and keyboards/orchestra.
Tunings and frequencies (lowest string)
| Tuning | Note | Frequency |
|---|---|---|
| Standard | E2 | 82.4 Hz |
| Drop D | D2 | 73.4 Hz |
| Drop C | C2 | 65.4 Hz |
| B standard (or 7-string) | B1 | 61.7 Hz |
| 8-string (F#) | F#1 | 46.2 Hz |
Lower tunings = one-finger power chords, riffs on the open string, sub-bass energy (watch out for how it fits with the electric bass and kick).
The tritone
The tritone (diabolus in musica) is the symbol of metal: the riff of the song Black Sabbath (Black Sabbath, 1970) is built on G – G (octave) – C#/Db, that is, a tritone. The tritone appears as the b5 above the tonic in riffs (E – Bb), in guitar harmonizations and in diminished arpeggios.
Modes and scales
| Scale | Characteristic note | Use in metal |
|---|---|---|
| Aeolian | b6 | classic heavy metal, melodic death |
| Phrygian | b2 | thrash, death: riffs on E – F |
| Phrygian dominant | b2 and major 3 | neoclassical, oriental metal |
| Harmonic minor | major 7 (leading tone) | neoclassical (Malmsteen), power metal |
| Locrian | b5 | very dissonant riffs |
| Diminished / whole-tone | symmetries | “scary” arpeggios and passages |
| Chromatic | semitones | “chug” riffs and death metal |
Typical progressions (E)
| Progression | Chords | Color |
|---|---|---|
| i – bVI – bVII | E5 – C5 – D5 | epic (Aeolian) |
| i – bII | E5 – F5 | Phrygian, menace |
| i – bV | E5 – Bb5 | tritone, horror |
| i – bVI – bIII – bVII | Em – C – G – D | power/melodic metal |
| i – iv – V (harmonic minor) | Em – Am – B | neoclassical |
| chromatic | E5 – F5 – F#5 – G5 | thrash, stoner |
| pedal | E – (melody over the open string) | thrash, djent |
Harmonizations
- Twin guitars in thirds (Iron Maiden, Thin Lizzy): two guitars harmonized in diatonic thirds in the minor scale.
- Parallel fourths and fifths: a more archaic and “massive” sound.
- Octaves: clarity in the themes.
- Black metal: open chords with dissonances (seconds and ninths) played with tremolo picking.
- Djent/progressive: extended chords (add9, maj7) and clean clusters alternating with rhythmic riffs in polyrhythm.
Tips for the producer
- The lower the tuning, the simpler the chords below must be: below 100 Hz, play only the root (and the fifth at most).
- The electric bass doubles the root of the power chord, often an octave below; lock it with the kick (double kick in sixteenth notes at 180 BPM = 12 hits per second).
- Chords with a third belong in the keyboards, the orchestra or the clean guitars.
Exercise
- Riff in drop D at 140 BPM: D5 (open string) in sixteenth notes with accents, then Eb5 (b2) and Ab5 (b5): Phrygian + tritone.
- Second guitar: harmonize the chorus melody in thirds in the D natural minor scale.
- Bridge: Dm – Bb – C (i – bVI – bVII) with orchestral keyboards playing the thirds.
Related
Flamenco Phrygian and metal, Aeolian and Locrian, Mixolydian in rock, the harmonic series and timbre, Andalusian cadence.