Power chord

What it means

A power chord consists of only the root and the fifth, often supplemented by the octave of the root. The third is absent, and with it the commitment to major or minor. The term comes from rock and pop music; the usual chord notation marks it with an appended 5.

Musical use

It owes its spread to the electric guitar with distortion. Distortion produces additional partials and combination tones; with a complete triad this creates so many frictions that the sound becomes dirty and unclear. The perfect fifth, by contrast, rests on a simple ratio and remains clear and forceful even under heavy distortion. A practical advantage is added: the fingering shape on the guitar is movable, so that chord progressions can be played with a single hand shape.

Because the third is absent, the sonority fits over major as well as minor harmonies; the mode results from the melody, the bass, or the context.

Musically theoretically notable is that sequences of power chords are nothing other than parallel fifths — exactly what is forbidden in strict writing. In this context, however, it is not about the independence of voices but about a tone colour, and the parallels are intended. This vividly shows that rules of part-writing are bound to particular styles.

Often the fifth is additionally doubled an octave higher, so that three notes sound. In the chord symbol it is designated with 5, for instance E5. On the electric guitar it is usually gripped with two or three fingers on the low strings and shifted in parallel. It is the basic building block of many rock, punk, and metal riffs. In English it is also called a fifth chord.

Performance practice

Damp the unneeded strings carefully, so that no unwanted notes sound along — especially under distortion, every extraneous tone stands out. Watch for clean intonation of the fifth; pressure on the string easily detunes it sharp. And check, when playing together, which mode the melody and bass prescribe.