The Triads And Pseudo-Triads Of Music


The most basic chords in music are called triads. A triad is made of three notes, hence the name. It's a tertian chord, meaning that it is built from stacking thirds. Therefore a triad consists of a first, a third, and a fifth scale degree. This article will discuss the 4 triads of music, their inversions, and what I call the “pseudo-triads.”


A Brief Overview Of Tertian Harmony

Tertian harmony is the most common way we build chords in western music. Tertian chords are constructed by stacking thirds, which means taking every second note of a scale. Let's look at the C Major Scale to illustrate.

Four Triads

So by stacking thirds starting on C, we'd have C  E  G  B.

  • E is a third above C
  • G is a third above E
  • B is a third above G

Continuing the pattern, we change the names of the scale degrees slightly to:

Four Triads
  • D is a third above B
  • F is a third above D
  • A is a third above F
  • is a third above A, completing the cycle

This tertian harmony is so common that we assume it in our chord names unless stated otherwise. For example, a major ninth chord is a chord with the scale degrees 1  3  5  7  9.

This is all a bit advanced but is the basis of chord construction. Since triads are the most basic chord, it's nice to add this little tertian harmony explanation.

A triad is a chord built by stacking two consecutive thirds. Thirds can be either minor or major.

Therefore, the four basic triads of music are:

  • Diminished Triad = minor third + minor third
  • Minor Triad = minor third + major third
  • Major Triad = major third + minor third
  • Augmented Triad = major third + major third

Written with scale degrees, these 4 triads are:

  • The Diminished Triad – 1   ♭3   ♭5
  • The Minor Triad – 1   ♭3      5
  • The Major Triad – 1      3       5
  • The Augmented Triad – 1      3    ♯5

These are the 4 basic chords of western music.

But “basic” doesn't necessarily mean overused, as the diminished and augmented triads aren't often used unless as transition chords. For example in Diatonic or Functional Harmony, there is only one diminished triad (which is rarely used) and no augmented triad. The minor and major triads, however, show up 3 times each! The major and minor triads are very common and make up most of the music we hear.

So now that we know the names of the four triads, let's dive a bit deeper into each of them!


The Major Triad –  1      3       5

The major triad is made from the intervals of the root, major third (2 whole steps), and perfect fifth (3 whole steps + 1 half step). Based on C, this gives the notes C      E      G.

It is the major third that differentiates the major triad from the minor triad.

The cliche is to say that a major chord sound “happy.” And in most contexts, it does sound happy, bright, cheerful, uplifting, etc. But on its own, a better word to describe the major triad is “stable.”

The perfect fifth is the most consonant interval other than perfect unison or the octaves. And this interval plays greatly into the stability of both the major and the minor triad.

The major third is a good distance between the root and the fifth as well. There is, of course, a major third interval between the 1 and 3 (2 whole steps), but also a minor third interval between the 3 and 5. These intervals are not necessarily consonant, but not dissonant either, and so the major triad is stable!

This stability means the major triad is great as a tonic chord in a major key.


A Quick Aside About Stability And The Harmonic Overtone Series

The harmonic overtone series is a natural phenomenon, and therefore can be studied with Physics. Physics states that a pitched sound (a note) will have a fundamental frequency and varying amounts of harmonics above it. These harmonics are simply multiples of the fundamental frequency.

So if we play a C at ~131 Hz, its harmonics include varying amounts of

  • ~262 Hz (131 x 2),
  • ~393 Hz (131 x 3),
  • ~524 Hz (131 x 4),
  • ~655 Hz (131 x 5), and so on.

These overtone series harmonics come very close to creating intervals with the fundamental frequency. They start with:

  • octave (x2),
  • perfect fifth (x3),
  • octave (x4),
  • major third (x5),
  • perfect fifth (x6)…

So by adding in a perfect fifth and major third, we are further solidifying the naturally occurring frequencies of the root note. This is, in part, why the major triad is so stable.

The harmonic overtone series is a bit advanced compared to triad study, and I'll have an article on it soon. Consider this a quick aside in as few words as I could write.


Back To The Major Triad

So we know the intervals required in root position, but we can voice triads any way we please. For example, a G major chord played in open position on the guitar could yield the notes (in order) of G, B, D, G', B', G”, or in scale degrees: 1, 3, 5, 1′, 3′, 1” (the ‘ means an octave above the root). We can have any number of notes across any octaves in the chord, as long as those notes are either the root, major third, or perfect fifth.

The root doesn't even need to be in the bass! This is where we get into inversions. A chord inversion means that the 1 is not in the bass. We number these inversions by the order in which the new bass note would appear sequentially in the original tertian chord. Since triads only have three notes, there is only a root position, first inversion, and second inversion. Let's check them out:

Root Position Major Triad

Root position simply means that the root is in the bass (the lowest note). So that G major chord stated above is in root position. The simplest form of root position is stacking 1  3  5, but as long as the root is in the bass, you can add any number of roots, thirds, and fifth above it and remain in root position!

This audio clip is a C major triad in root position (C   E   G):

A favourite voicing of mine is a root position “split voicing.” This is when the root and fifth are played with the third an octave above. I really love this voicing on piano.

This audio clip is a C major split triad (C   G    E'):

First Inversion Major Triad

First inversion is when the next note, the third, is in the bass. The C major triad is made of C E G, and so its first inversion, most simply, is voiced E G C. The major third is in the bass.

This audio clip is a C major triad in first inversion (E   G   C):

Note that when I state “most simply,” I mean that all the notes are as close together as possible. Remember that as long as the 3rd is in the bass, we can add any amount of triad tones above it and remain in first inversion

In root position, we have a major third and perfect fifth interval compared to the bass note. In first inversion, we have a minor third and a minor sixth interval compared to the bass note. Swap these voicings for added interest in your chord progressions 🙂

Second Inversion Major Triad

As you can probably guess, the second inversion of the major triad has the 5th in the bass. The simplest C major chord in second inversion is made of  G C E. Mark Levine writes in The Jazz Theory Book that “triads sound strongest in second inversion.” Perhaps this is because of the strong perfect fourth interval in the bass (between the 5th and the 1). This is debatable, of course, but these three voicing can be interchanged in composition to add some interest to our chord progressions.

This audio clip is a C major triad in second inversion (G   C    E):

With those thoughts in mind, let's check out the minor triad!


The Minor Triad – 1   ♭3      5

The minor triad is also a very stable chord. It has a minor third (1 whole step + 1 half step) and perfect fifth interval (3 whole steps + 1 half step) above the root. Another way to call out the intervals is that it has a minor third (1-♭3) followed by a major third (♭3-5).  It is the minor 3rd that differentiates the minor triad from the major triad.

“The minor triad sounds sad” is another cliche. It can sound sad, solemn, or moody in the proper context. It is certainly darker than the major triad, but stable enough to be the tonic chord in a minor key!

We've already discussed inversions, so let's quickly look at the minor triad's inversions using C minor as an example.

C minor = C     E♭  G

Root position means that the root is in the bass. The simplest form of a C minor triad in root position is 1   ♭3     5 = C     E♭  G.
A minor third interval followed by a major third interval.

This audio clip is a C minor triad in root position (C     E♭  G):

First inversion means that the first scale degree above the root is in the bass (♭3     5      1) or in the simplest case of C minor: E♭  G      C.
A major third interval followed by a perfect fourth interval.

This audio clip is a C minor triad in first inversion (E♭  G      C):

Second inversion means that the second scale degree above the root is in the bass (5     1   ♭3) or in the simplest case of C minor: G    C     E♭.
A perfect fourth interval followed by a minor third interval.

This audio clip is a C minor triad in second inversion (G    C    E♭):

Remember, as always, that if the root, minor third, and perfect fifth are the only notes, you are indeed playing a minor triad. It doesn't matter how many duplicates there are of each scale degree or in what octave they are played in.

With that in mind, experiment with different voicings!

Like I mentioned, one of my favourite triad voicings is simple: the root and fifth in the bottom and the third played an octave up. This is called a “split triad voicing.” It's a staple in my compositions (especially when voiced with a piano!)

This audio clip is a C minor split triad (C   G    E♭'):


Minor And Major Triads In Action

Most music and chord progressions are based on the diatonic scale (aka the major scale) and the chords it yields. Functional harmony uses the diatonic scale as a base for harmony and assigns these chords a function (tonic, predominant, or dominant). More on that here.

Let's look at the triads the diatonic scale produces by stacking thirds in C Major:

Triads

These are the basic chords of almost all western harmony. And they are mostly major or minor triads. Except for the 7 chord (we'll get to the diminished triad shortly)

Major and minor triads are everywhere. You could write all your compositions with only these chords and they would sound great!

But there are two more, less utilized triads that are worth talking about. Let's start with the 7 chord in functional harmony:


The Diminished Triad – 1   ♭3   ♭5

The diminished triad is the darkest triad of the four. It sounds really tense, dark, spooky, evil, etc. The minor third is dark, but add in the diminished fifth (tritone) and the triad becomes really unstable.

Another way of stating the intervals of the diminished triad is two minor thirds stacked on top of one another. It's a really tense triad and you'll most commonly hear it resolve up a half step to the tonic major chord (in functional harmony).

I like using the diminished triad in my compositions because of its darkness and because its chord that's not used all that often (how hipster of me lol).

The simple inversions of the diminished triad base on C are as follows:

Root position: 1   ♭3   ♭5   or   C     E♭  G♭

First inversion: ♭3  ♭5     1   or   E♭  G♭   C

Second inversion: ♭5     1   ♭3   or   G♭   C     E♭


The Augmented Triad – 1      3    ♯5

The augmented triad is the least common triad in music. It's the brightest, but almost too bright. The two major thirds stacked on top of one another create an odd dissonance. The augmented triad's sound is unstable, unnerving, and unresolved. It doesn't serve a dominant function and so it's difficult to say where the tension will resolve.

Once again, I try to sneak this triad into my compositions but it's a tough one to make sound pretty.

An interesting thing about the augmented triad is that it breaks an octave equally into three parts. This means that instead of having 12 different triads based on each of the notes of the chromatic scale (like the major, minor, and diminished triads), there are only 4 different augmented triads. By the same token, we can't truly do inversions with the augmented triad because the inversions would be root positions of a different chord.

Root position:            1     3  ♯5   or   C     E     G♯

First inversion:         3  ♯5    1   or   E     G♯  C       (E aug. triad = C aug. triad)

Second inversion:♯5     1    3   or   G♯  C      E       (G♯ aug. = E aug. = C aug.)


Recap

So by stacking thirds, we create four types of triads: the Major, Minor, Diminished, and Augmented. The major and minor triads are by far the most common. Followed by the diminished triad (since it's found in functional harmony). And the rarest triad is the augmented triad.

Try to add (no pun intended) these uncommon triads to your compositions and see what results you can come up with!

Before we wrap this article up, I'd like to take a few paragraphs to talk about suspended chords and pseudo-triads.


Suspended Chords

Suspended chords are similar to major and minor triads with a root and perfect fifth. But in suspended chords, the major or minor third is omitted and replaced with either a second (sus2) or a fourth (sus4).

I often refer to suspended chords as pseudo-triads. They're not built by stacking thirds, but I like looking at them as triads that have had their third replaced by a second or fourth degree.

The Suspended Second Chord – 1   2   5

The interval between the 2nd and the 5th (perfect fourth) in a sus2 chord creates an open sound (not major and not minor), while the interval between the root and the 2nd (major second) creates tension.

This audio clip is a Csus2 chord in its three voicings (C    D    G):

The Suspended Fourth Chord – 1   4   5

The interval between the root and the 4th (perfect fourth) in a sus4 chord creates an open sound (not major and not minor), while the interval between the 4th and the 5th (major second) creates tension.

This audio clip is a Csus4 chord in its three voicings (C     F     G):

Note that the sus2 chord is an inversion of the sus4 chord and vice versa.

In our sus2 example, we had the notes C D G (Csus2). And if we rearrange them as G C D, we have Gsus4.

Similarly, in our sus4 example, we had the notes C F G (Csus4). And if we rearrange those as F G C, we have Fsus2.

These “sus” chords are not technically triads since we're no longer stacking thirds, but they're worth mentioning here and I like to include them as pseudo-triads when thinking about possible “triads” to play in a certain key or modal setting.

Speaking of modal setting, let's take these suspended chords a step further and introduce what I call “modal pseudo-triads,” by flatting the 2nd in the sus2 chords and sharping the 4th in the sus4 chord:

The Phrygian Pseudo-Triad – 1   ♭2    5

This chord has a very dissonant minor second interval between 1 -♭2 and another dissonant tritone interval between ♭2 – 5. The Phrygian “triad” is therefore unstable, but it has its place in musical composition.

The main reason I use this pseudo-triad is to establish or play inside the Phrygian mode. The Phrygian mode is characterized by the tritone between its ♭2nd and 5th scale degrees. So this chord has both the root and important characteristic tones of the mode.

When using this dissonant pseudo-triad, try to keep it in the upper register. Playing this chord too low in the frequency spectrum sounds really muddy and dissonant, which can be used to great effect, but sounds more “terrible” than it does “modal.”

This audio clip is a C Phrygian pseudo-triad in its three voicings (C   D♭  G):

The Lydian Pseudo-Triad – 1   ♯4    5

Much like the Phrygian pseudo-triad, the Lydian pseudo-triad has a tritone interval and a minor second interval. The ♯4 is the characteristic tone in the Lydian mode, creating a tritone interval with the root.

This “triad” is great in the Lydian mode. And again, like the Phrygian, it sounds best when voiced in the upper register!

This audio clip is a C Lydian pseudo-triad in its three voicings (C    F♯  G):

Note that, unlike the regular sus2 and sus4, the sus♭2 and sus♯4 are not inversions of one another.


Conclusion

There are plenty of three-note chords, but only 4 true triads. Although the major and minor triads are by far the most common, there is always room for experimentation with the others.

Do you have a favourite use for a certain triad or pseudo-triad? Please share in the comments below. I'd love to hear from you!

As always, thanks for reading and for your support.

Arthur

Arthur is the owner of Fox Media Tech and author of My New Microphone. He's an audio engineer by trade and works on contract in his home country of Canada. When not blogging on MNM, he's likely hiking outdoors and blogging at Hikers' Movement (hikersmovement.com) or composing music for media. Check out his Pond5 and AudioJungle accounts.

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