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Learn how to build the four types of triads.
Focus on how and where to use the two most common triads.
Learn some common chord progressions using triads.
You just know when you’re listening to some truly beautiful music. You can tell when a beat and a bassline are so good that they seem to lift you up out of your seat and raise goosebumps on your skin.
You know there’s an innate sense of tension and release seemingly built into the music, but you’re still working on unlocking the secret to whythe music impacts you this way.
The goal of this article is to help you unlock part of that secret by decoding the four types of triads: major, minor, augmented, and diminished. We’ll focus particularly on the high-utility major and minor triads that form the foundation of most of the music we hear.
What Is A Triad?
As the prefix tri suggests, a triad is a chord composed of three distinct pitches, or chord tones, in a particular configuration: a root, third, and fifth.
The formula for building any triad begins with the root, which is the pitch class that gives a triad its name. The C triad, for example, has C as its root. The next note, the third, must be separated from C by either a major third or a minor third.
Major thirds are equal to 4 semitones, whereas minor thirds are equal to 3 semitones. Thus, in a C triad, this pitch will be some sort of E – either an E-natural or an E-flat.
The fifth in a C triad must be a fifth above C. In the case of an augmented triad, it will be an augmented fifth, making it a G-sharp. In the case of the major and minor triads, it will be a perfect fifth, making it a G-natural.
In the case of a diminished triad, it will be a diminished fifth, making it a G-flat. An augmented fifth is equivalent to two major thirds, or 8 semitones. The perfect fifth is equivalent to a major third and a minor third, or 7 semitones. A diminished fifth is equivalent to two minor thirds, or 6 semitones. This is probably best explained with a picture like the one below:
Though the different C triads are composed of different pitches, what they each have in common are the note names C E G; you just have to alter the accidentals in order to arrive at the correct notes for each triad. As is the case with most formulae in music theory, the formula for each triad can be transposed to any key, so you only have to start with a root and know which type of third and fifth you want in order to build any triad.
The four F triads, for example, are each composed of F A C: The F augmented triad is F A C♯, the F major triad is F A C, the F minor triad is F A♭ C, and the F diminished triad is F A♭ C♭.
It is important to note here that any pitch with a note name and no explicitly-notated accidental (sharp, flat, or natural) is assumed to be natural.
Inversions And Doubling
The pitches of a triad can be arranged in any order. When the root serves as the lowest note (also known as the bass note), the triad is in root position. When either of the other notes serve as the bass note, the triad is in an inversion (for more on inversions, see our article on chord inversions).
It should be noted as well that, while one of each of the chord tones (root, third, and fifth) is mandatory for a chord to be a triad, any of these notes can be doubled so that the triad is composed of more than three notes. Any chord tones outside of the root, third, and fifth, however, would alter the quality of the chord, changing it from a triad to some other chord due to the presence of a fourth pitch class.
Why Are Major And Minor Triads Most Common?
At this point I’ll pivot my attention away from the theory behind triads and towards applications for them. One last point I should make, however, has to do with why we’ll be focusing primarily on the major and minor triads from here on out.
The term diatonic denotes a relationship to a particular key area. Diatonic triads are thus the triads found in a key area (for more on key areas, see our series on minor scales). The diatonic triads of C major, for example, are triads composed solely of the pitches C D E F G A B.
Though the above image depicts the triads of the C Major key area, the same formula can be applied to any major key area, with the same results: of the seven distinct diatonic triads of a major key area, three are major, three are minor, only one is a diminished triad, and none are augmented triads.
Because A minor is the relative minor of C Major, it contains all the same pitches. This arrangement of pitches and the thirds-based relationships that constitute triads will result in the same diatonic triads in a minor key area that are found in a major key area, just in a different order.
Thus, of the seven distinct diatonic triads of a minor key area, three are major, three are minor, only one is a diminished triad, and none are augmented triads.
The Character Of Triads
It is crucial to note here that music is a cultural construction, so while a lot of music theory can be mathematical in nature and seemingly objective, the application of musical constructs is entirely subjective.
For more on this, check out Ed Yong’s piece in The Atlantic about the debate over universal traits in music. However, if you, like me, grew up watching popular films and hearing popular music pumped into public spaces, you have been inducted into a cultural understanding that triads have different characters.
The Major Triad
Objectively, the major triad is a root note, the note found a major third above the root, and the note found a perfect fifth above the root. Subjectively, it is cheerful, energetic, hopeful, positive, bright, happy, or good, depending on its context. Music composed in a major key generally centers on a major triad as the tonic triad, around which the rest of the music revolves and to which the harmony typically resolves.
The Minor Triad
If you simply take a major triad and move the third down a semitone, you end up with a minor triad. Such a small difference has a huge impact on our perception of the chord, though, as we perceive the minor triad to be serious, plaintive, pessimistic, negative, dark, sad, or bad, depending on the context. From the moment we hear music composed in a minor key and centering a minor triad, we know we are listening to music of a serious nature.
Why Not Both?
Though it is possible to write music entirely out of major triads or entirely out of minor triads, it is much more common to hear music that centers a single triad as the tonic, essentially the home triad, and bounces around to different triads that can be major or minor.
For this reason, it makes more sense to discuss triads in terms of functional harmony than to present them strictly in terms of major or minor quality.
Functional harmony is a way of looking at chords and how they relate to each other. It distinguishes between diatonic triads in terms of what each triad does and where it can lead. Since the basic principles of functional harmony apply to any key area, the chords can be notated using neutral Roman numeral notation as opposed to specific chord names.
For example, instead of notating the diatonic triads of C Major as C Maj, D min, E min, F Maj, G Maj, A min, B dim, C Maj, you could notate them as I, ii, iii, IV, V, vi, viio, I.
The same would apply in minor: instead of notating the diatonic triads of a minor as A min, B dim, C Maj, D min, E min, F Maj, G Maj, A min, you would notate them as i, iio, III, iv, v, VI, VII, i.
Whether in a major key area or a minor key area, the tonic triad is the point from which the harmony tends to depart from and return to. In a major key area, the tonic triad is I, the major triad built on the first scale degree, whereas in minor it is i, the minor triad built on the first scale degree.
In some cases, vi (in major key areas) and VI (in minor key areas) can act as tonic-function chords. In other cases, they have more of a pre-dominant feel. For this reason, they tend to walk the line as a sort of gray area triad that is guaranteed to add some interest to a chord progression.
Dominant triads perform the function of leading back to the tonic. By the time a chord progression reaches the dominant-function triad, the tension has reached the critical point at which the most common direction is towards resolution. For this reason, the dominant-function triad can be thought of as a sort of opposite pole to the tonic-function triad.
By far the most common dominant-function triad is V, in both major and minor keys. In major key areas, V is a diatonic triad, and in minor key areas it is common to raise the 7th by a semitone so as to make it a leading tone and give V its dominant quality. Leaving scale degree 7 in its lower position in minor will yield a v triad that offers a softer, less dramatic resolution to i.
Another dominant function triad in both major and minor key areas is viio, as the same modification of scale degree 7 will yield a diminished triad in minor key areas to match the diminished triad that is diatonic in major keys.
Without the modification of scale degree 7, you are left with a VII chord that, in resolving to i, sounds just like the V resolving to vi (also known as a deceptive cadence) in the relative major.
The pre-dominant triads function as their name would suggest: they are intermediaries between tonic-function triads and dominant-function triads. They serve to delay the arrival of the dominant and subsequent resolution to the tonic. In doing so, they reinforce the tonality of the key area and help to regulate harmonic rhythm and the accumulation of tension.
As I mentioned previously, vi and VI sometimes fall within the tonic-function triad and other times function as pre-dominant triads. The other pre-dominant triads in major are IV and ii, and in minor are iv and iio.
Traditionally, the pre-dominant could only lead to the dominant. However, it is increasingly common in popular music to forego the dominant entirely so as to avoid the drama and sense of finality that comes with authentic cadences from dominant to tonic. In this case, the dominant-function pole is removed from the chord progression and the pre-dominant assumes a lesser version of this functionality as the opposite to the tonic-function triad.
Triads In Action
Now that you know the theory behind the construction of triads and their applications, we ought to spend some time with popular chord progressions so that we can see our triads in action. The following examples are just a few chord progressions from the infinite realm of possibility we have at our disposal when we have a solid foundation in the theory behind triads and their application.
This I – IV – V – I chord progression is very basic but outlines nicely the traditional harmonic motion from tonic through pre-dominant to dominant and back to tonic.
The ii – V – I chord progression can be heard throughout jazz music, and features one minor triad and two major triads. Within the context of jazz music it is more common for the ii and V chords to be seventh chords than triads, but for our purposes, the triads sound good too.
As mentioned earlier, it is increasingly common for chord progressions to get by without a V or viio chord, instead utilizing a pre-dominant chord as a sort of substitute dominant-function chord for a softer harmonic oscillation back and forth with tonic. The above image depicts just such a chord progression.
Here, we see an example of how scale degree 7 (in this case G) can be raised a semitone (in this case to G-sharp) to turn v to V in a minor key area.
The above image depicts an example of a deceptive cadence, in which V resolves to vi instead of I in major, or VI instead of i in minor. This would be an example of vi acting as a tonic-function chord instead of a pre-dominant function chord.
As is the case with most aspects of music theory, the study of triads is composed of a multitude of layers. There are the four basic formulae used to construct the four different triads, but understanding these is not quite enough to get us writing coherent music.
Beyond that, there is the understanding of where these triads occur within a key area. But even that might not suffice, so then the study of functional harmony gets us to the point at which we really begin to understand the relationships between these triads.
Still, there are many layers beyond those we have covered here, so it is my hope that this brief exploration of the four types of triads and how to use them has only just whetted your appetite and left you hungry for more.
Check out these other articles if you want to improve your songwriting skills: