In guitar music, especially electric guitar, a Power Chord (also fifth chord) is a chord that consists of the root note and the fifth. Power chords are commonly played on amplified guitars, especially on electric guitar with distortion. They are a key element of many styles of Rock and especially Heavy Metal music.
Power chord on E
When two or more notes are played through a distortion process that non-linearly transforms the audio signal, additional partials are generated at the sums and differences of the frequencies of the harmonics of those notes (intermodulation distortion).
When a typical chord containing such intervals (for example, a major or minor chord) is played through distortion, the number of different frequencies generated and the complex ratios between them, can make the resulting sound messy and indistinct. This effect is accentuated as most guitars are tuned based on equal temperament, with the result that minor thirds are narrower and major thirds wider, than they would be in just intonation.
However, in a power chord, the ratio between the frequencies of the root and fifth are very close to the just interval 3:2. When played through distortion, the intermodulation leads to the production of partials closely related in frequency to the harmonics of the original two notes, producing a more coherent sound. The intermodulation makes the spectrum of the sound expand in both directions, and with enough distortion, a new fundamental frequency component appears an octave lower than the root note of the chord played without distortion, giving a richer, more bassy and more subjectively ‘powerful’ sound than the undistorted signal.
Even when played without distortion, the simple ratios between the harmonics in the notes of a power chord can give a stark and powerful sound, owing to the resultant tone effect.
Power chords also have the added advantage of being relatively easy to play (see “Fingering” below), allowing fast chord changes and easy incorporation into melodies and riffs.
Theorists are divided on whether a power chord can be considered a chord in the traditional sense, with some requiring a ‘chord’ to contain a minimum of three degrees of the scale. When the same interval is found in traditional and classical music, it would not usually be called a “chord”, and may be considered a dyad (separated by an interval). However, the term is accepted as a Pop and Rock music term, most strongly associated with the overdriven electric guitar styles of Hard Rock, Heavy Metal, Punk Rock and similar genres. The use of the term “Power Chord” has, to some extent, spilled over into the vocabulary of other instrumentalists, such as keyboard and synthesizer players.
Power chords are most commonly notated 5 or (no 3). For example, “C5” or “C(no 3)” refer to playing the root (C) and fifth (G). These can be inverted, so that the G is played below the C (making an interval of a fourth). They can also be played with octave doublings of the root or fifth note, which makes a sound that is subjectively higher pitched with less power in the low frequencies, but still retains the character of a power chord.
Another notation is ind, designating the chord as ‘indeterminate’. This refers to the fact that a power chord is neither major nor minor, as there is no third present. This gives the power chord a chameleon-like property; if played where a major chord might be expected, it can sound like a major chord, but when played where a minor chord might be expected, it sounds minor.
Power chords can be traced back to commercial recordings in the 1950s. Robert Palmer pointed to electric blues guitarists Willie Johnson and Pat Hare, both of whom played for Sun Records in the early 1950s, as the true originators of the power chord, citing as evidence Johnson’s playing on Howlin’ Wolf’s “How Many More Years” (recorded 1951) and Hare’s playing on James Cotton’s “Cotton Crop Blues” (recorded 1954). Link Wray is often cited as the first mainstream rock and roll musician to have used power chords, with “Rumble” (recorded 1958).
A later hit song built around power chords was “You Really Got Me” by the Kinks, released in 1964. This song’s riffs exhibit fast power-chord changes.
The Who’s guitarist, Pete Townshend, performed power chords with a theatrical windmill-strum, for example in “My Generation”. An example of the use of power chords is Deep Purple’s “Smoke On The Water”. On King Crimson’s Red album, Robert Fripp thrashed with power chords.
Power chords are often performed within a single octave, as this results in the closest matching of overtones. Octave doubling is sometimes done in power chords. Power chords are often pitched in a middle register.
Spider Chords – The spider chord is a guitar technique popularized during the 80s Thrash Metal scene. Regarded as being popularized (and the term “spider chord” coined) by Dave Mustaine of Megadeth, it is used to reduce string noise when playing (mostly chromatic) riffs that require chords across several strings. The chord or technique is used in the songs “Wake Up Dead”, “Holy Wars… The Punishment Due” and “Ride the Lightning”.
As seen in the right tab, the two power chords may be played in succession without shifting, making it easier and quicker and thus avoiding string noise. The normal fingering would be 3 / 1 for both chords, requiring a simultaneous shift and string change. Note that the two power chords are a major third apart: if the first chord is the tonic the second is the minor submediant. The spider chord fingering also allows access to a major seventh chord without the third. The spider chord requires the player to use all four fingers of the fretting hand, thus its name. This technique then allows one to run down the neck playing either of the two chords.
Fingering – Perhaps the most common implementation is 1-5-1′, that is, the root note, a note a fifth above the root, and a note an octave above the root. When the strings are a fourth apart, especially the lower four strings in standard tuning, the lowest note is played with some fret on some string and the higher two notes are two frets higher on the next two strings. Using standard tuning, notes on the first or second string must be played one fret higher than this. (A bare fifth without octave doubling is the same, except that the highest of the three strings, in parentheses below, is not played. A bare fifth with the bass note on the second string has the same fingering as one on the fifth or sixth string).