Power Chords

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1. Omit Notes

In Chapter I, we learned the technique to add notes to basic triads, which is called “seventh chords” or “tension chords”. But you can get new sounds by doing totally reverse—Subtracting a note.

Removing notes from a chord is specifically called Omit. For example, a C chord with its 3^rd omitted is labeled as “C_(no3)” or “C_omit3“.

It’s a chord name used only when you want to explicitly state that you are omitting notes, so there are not many occasions to use it. In the first place you may wonder why and when you omit notes. Let’s take a look at it.

2. Power Chords

Among the various types of omits, the one overwhelmingly used is “omit3”. This is because it is extremely common in the world of rock music. Before getting into the theoretical discussion, let’s first listen to the sound!

When played with heavily distorted guitar, omit3 chords sound really powerful. Therefore it is lovingly called a Power Chord. In fact, in genres like hard rock or metal, power chords are the basic form of their guitar play, instead of traditional major/minor chords.

When omit3 is referred to as a “power chord,” the chord symbol “5” is commonly used.

The power chords are used so frequently in rock that declaring “no3” or “5” is often omitted in band music score, and it may simply be written in normal triads (in that case, they may indicate in tablature that it is a power chord)

Why do rock and other rock-related genres love power chords? There’s an interesting background to be explained…

Easy to Play

First, power chords can be very easily played with a guitar.

You need just 3 fingers and sliding your hand can get another power chord (or you can play power chords even with 2 fingers by omitting the duplicated highest note).

There’s virtually only one hand shape you need to memorize. Once you’ve got that single shape, you can play power chords from all 12 roots just by moving your hand position. So it might not take you more than a day to get to the point where you can play “Smells Like Teen Spirit”.

It’s beyond doubt that the easiness of playing power chords helped facilitate the explosive spread of rock music especially in the late 20^th century.

“God Save The Queen” is a very famous punk rock song released in 1977. The song is also played mainly power chords, and especially in the last part (2:47-) you can visually confirm how simply the guitarist slides his hand with its form fixed.

Easy to Make Chord Progression

3^rd is fundamentally crucial for chords, as it determines whether it’s a major or minor chord, playing an incredibly vital role in chord structure.

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If you omit 3^rd, both C and Cm becomes C5. There’s no knowing which one it’s originated from. However, this is actually a fortunate phenomenon, especially for those who are not well-versed in music theory. They no longer need to care about the manners that I, IV, and V chords should be major, while the II, III, and VI chords should be minor.

Say you make 1-5-6-4 progression in the key of C, generally you have to use CGA_mF. It requires a bit of knowledge to use a minor chord for VI while all the others major. As long as you use power chords, you won’t encounter such issues. You simply play C₅G₅A₅F₅ and it sounds good. You can imagine how this has made it easy for punk rockers to write songs.

In Nexus Theory, we explained how the structure of the guitar led to chord progressions that differ from traditional tonality. However, power chords have contributed to the songwriting based on traditional tonality at the same time.

Clarity of Sounds

There’s another reason power chords are loved by rock guitarists, which is from the perspective of acoustics. The sounds of distorted guitars are very “rich”. Technically speaking, it means the richness in the spectrum of frequencies. Casually put, it means that the sound is shimmering, bright, and has a noticeable presence. So even a simple C triad chord can sound too full and harsh when played with a distorted guitar.

The C major chord played with the guitar sounds a bit muddy. Using power chords can avoid this issue.

Though it loses the quality of major/minor, even that can work as a good thing when you don’t want minor key or minor chord to sound too sad. For example, 1-5-6-4 progression moves from major to minor at V→VI_m, which can be used to convey a melancholic mood, but this doesn’t happen in power chords.

Normal major/minor

Power chords

Thus the impression of the whole chord pregression becomes drier, hopefully more cheerful.

Getting Away from Tradition

3^rd is the note that determines the color of a chord. In classical music, it’s often explained as a “note not to be omitted except when seeking a special effect”. Or in jazz, it’s considered the most crucial note and is generally not omitted¹.

In classical music, omitting the 3rd is not common.

In jazz, keeping the 3rd is fundamental, too.

Therefore, the sound without 3^rd eventually came to signify a departure from such “elegant” music, and its deviation from tradition may have offered a fresh appeal that was embraced by rock musicians.

So, with all these factors from various angles coming together, power chords have become a hallmark of rock music. The development of instruments and equipment like guitars and amps has played an important role in bringing new changes to music history.

3. Power Chord and Tonality

Some may wonder if tonality can be well established without 3^rd of every chord. But a succession of chords automatically suggests a specific key, and the melodies plyaed on it can also present a scale, so there’s no need to worry about that.

In this kind of environment, the role melodies play is significant. For example, when the altered 3^rd note is played by the melody, it can show a quality change even while the guitars remaining a power chord.

The chorus part of “Holiday” starts with 6-4-1-5 progression. In the second loop it’s changed to 6-4-1-3. They’re all power chords but the last phrase, “rest of our lives“, the melody goes to the altered (sharpened) 3^rd of III chord, constituting III instead of III_m.

A Dangerous Case

However, for example, if you play an A₅ chord at the beginning of a song, listeners won’t know if the song is in A major or A minor.

A₅D₅E₅

This is quite an extreme example, but even when you have three chords in a row, A-D-E, you still can’t tell if it’s in A major or A minor. So, what do you think will happen next in the music?
Typically, it would continue in A major. In that case, the scale used would be the A major scale with sharps on C, F, and G.

A₅D₅E₅

However, there’s still a possibility that it’s a song in A minor.

A₅D₅E₅

The creator knows everything, but a listener hearing this music for the first time won’t know what’s going to happen. There can be a disconnect between what the creator intended and what the listener perceives. So, it’s ideal to be aware of what can happen when 3^rd is absent.

4. Acoustics

Now that we’ve entered Chapter II, let me provide some additional information from the perspective of acoustics.

Firstly, the three tones of a power chord have a very simple ratio of frequencies, approximately 2:3:4.

And as explained in the article about timbre in Preparation section, every sound hads numerous frequency components in addition to the fundamental pitch detected by the tuner, and these components shape the timbre.

Now looking at the three tones of a power chord, they, due to the simple ratio of 2:3:4, share many lower-order harmonics.

For example, at a clear point, the component at 540Hz is six times the frequency of 90Hz, four times that of 135Hz, and three times that of 180Hz, thus all the chord tones of F5 have this frequency component. The more shared components there are, the more strongly the sounds blend together.

Furthermore, the distortion of guitar amps enrich the components of the timbre even more. As a result, what happens is that the three tones of a power chord are bundled together, sounding as if they were one thick sound!

Here is an example where we played power chords on 6-7-1-2 progression. At the VII, F^♯ note is included as a chord tone (because the fifth above B is F^♯, not F). This is an “accidental note” that deviates from the original key’s scale. However, unless you listen very very carefully, you probably won’t notice it. You’ll likely only hear the thick line of A–B–C–D.

If you don’t know this acoustic phenomenon, you might avoid playing this F^♯ note because it might seem “theoretically wrong”. However, in reality, whether you change this F^♯ to F or G, it stands out as unnatural.

Changed to F

Changed to G

Although the differences here are slight, these options sound much more unnatural. Therefore, in such particular conditions, playing F^♯ is the most standard choice. Occasionally, some “masters of theory” who are unaware of such situations of rock guitar may label this as playing out of key or incorrect, but when you consider acoustics, using F^♯ is a legitimate method.

Of course, the choice can vary depending on the context of the chord progression, type of instrument and the degree of distortion. So, in practice, you’ll have to use your ears to verify. These aspects related to acoustics are something you cannot learn by merely looking at sheet music, so always remember the importance of actually playing with sound.

5. Playing Riffs

In rock music, impressive phrases that are repeatedly played within a song are called Riffs.

When a riff phrase is not so fast, you can make it thick by using power chords.

The main riff of “Vertigo” is played with power chords so even with a single guitar it has enough thickness and power. In these cases power chords really feel more like a melody line rather than a chord progression. This is made possible by the characteristic of power chords where the notes merge into one thick sound.

Some theorists, given these situations, say that power chords are actually not “chords”, but just a thickened version of a single note. (Well, it doesn’t matter much whether or not.)

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The genre that commonly uses power chords is primarily rock. However, the idea of omitting 3^rd to create a sound without major/minor quality can be applied in many other genres as well. Chord arranging is not just about adding, but also about subtracting. Master both and you’ll reach the next level!

Summary

• Removing notes from a chord is referred to as “omitting” and a chord symbol “omit” is used.
• When you omit 3^rd from a major or minor chord in rock guitar, it’s called a “power chord“.

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