What is a triad?
A triad is a generic name used to describe chords that have a total of three notes per octave.
Triads can be tertian or non-tertian. In tertian triads, the interval between successive chord tones [when played in root position] is thirds. These root position triads are all tertian triads:
The distance [in pitch] between chord tones are thirds in each case. Here’s a powerful post you can read on tertian chords. Alternatively, there are triads that are built off seconds:
…and fourths:
Our focus in this post is on triads and our interest is narrowed down specifically to tertian triads – where chord tones are thirds apart.
Triad Chord Formation
Although the process of forming triads is as easy as stacking thirds together, it’s not just any third. There are various qualities of thirds ranging from major thirds to minor thirds, augmented thirds to diminished thirds. This means that from C, all options of thirds include the following:
Major third
Minor third
Augmented third
Diminished third
* the proper spelling of this diminished third is C-E♭♭ (E double flat).
Considering that there are lots of options (four of them), our choice of third is incumbent on the underlying scale. The major scale of C has the following tones:
We can stack thirds without being mindful of the quality of third. A third from C is E:
If another third is added to E, this will produce the C major triad:
A quick contrast between scale and chord tones…
…will bring to your attention that the chord tones of a triad are the first, third and fifth tones of the scale. Pursuant to this chord vs scale tone relationship, the three chord tones are known as the first, third and fifth with reference to their corresponding position in the underlying scale.
Therefore, let’s explore various qualities of triads that can be formed.
Chord Tones
Having established the chord tones of triads, let’s look at their individual contributions to the harmonic identity of triads.
The First – The Root
This is the first chord tone in a root position triad. The first is also known as the root of the chord because it determines the letter name of the chord.
The root position triad above is a D chord because the first chord tone (aka “root”) is D. A triad that has its root as the lowest note is called a root position triad. This is because, unless a triad (let’s say D min) is inverted to:
…the root will always maintain its position as the lowest chord tone.
The Third – Major vs Minor
Considering that our class of harmony is tertian harmony, the next chord tone is a third (not a second). The third is the chord tone where the primary quality of the triad is determined.
There are two primary qualities – major and minor. These primary qualities are tailored to adapt to the two tonalities we covered on the second day of Christmas.
Do you remember the other qualities of thirds we covered earlier – diminished and augmented thirds? They are not used in the third because the third is the chord tone where the tonal identity of a chord (whether major or minor) is determined.
In the major scale of C, a closer look at all possible thirds…
C-E from the first scale step which is a major third:
D-F from the second scale step which is a minor third:
E-G from the third scale step which is a minor third:
F-A from the fourth scale step which is a major third:
G-B from the fifth scale step which is a major third:
A-C from the sixth scale step which is a minor third:
B-D from the seventh scale step which is a minor third:
…will show that there are only two qualities of thirds. Time will fail me to go through all possible thirds on the natural minor scale and its variants – melodic and harmonic minor. At your leisure, check out the possible thirds in these scales.
Natural minor:
Harmonic minor:
Melodic minor:
The third of a chord is the chord tone where the primary quality is determined (major or minor). At this point, you’ll need to see our FREE 111-pg quick guide on Consonant Intervals: The Building Blocks of Major and Minor Triads where major and minor thirds are covered in all 12 keys.
The Fifth – Augmented vs Diminished
Still on tertian harmony, the next chord tone beyond the third is the fifth. The secondary quality of a triad is determined by the fifth. These secondary qualities include the diminished and augmented qualities.
Secondary qualities of triads are concerned with the stability of the triad. The perfect fifth is universally consonant, therefore, any triad that has the perfect fifth as an interval tends towards stability, whereas, other qualities of fifths (chromatic dissonance) like the augmented and diminished fifth tend towards instability, unrest, tension, etc.
Let’s consider the possible qualities of fifths that can be formed diatonically from one scale step to another:
C-G from the first scale step is a perfect fifth:
D-A from the second scale step is a perfect fifth:
E-B from the third scale step is a perfect fifth:
F-C from the fourth scale step is a perfect fifth:
G-D from the fifth scale step is a perfect fifth:
A-E from the sixth scale step is a perfect fifth:
B-F from the seventh scale step is a diminished fifth:
You’ll find perfect fifths on every degree of the scale except the seventh degree, where you’ll find the diminished fifth (see diabolus in musica). The augmented fifth is not found in the major scale, however, it can be found in the harmonic minor scale. The interval between E♭ and B is an augmented fifth.
There are two other qualities of triads based on secondary qualities – diminished and augmented and these qualities tend towards instability. Altogether, we’ve covered four qualities. Two primary qualities (major & minor) and two secondary qualities (augmented & diminished). Let me show you, step by step, how these primary and secondary qualities work.
Four Triad Qualities
The combination of these qualities (primary and secondary) can create four harmonic entities.
Stable Triads
Triads are considered stable when the interval from the first to the fifth tone is a perfect fifth. So, using perfect fifths like…
…we can create chord qualities using primary qualities – major and minor. Using a major and minor third, we’ll produce…
C major triad
C minor triad
Both triads may differ in quality, yet they share one thing in common – stability.
Unstable Triads
When the fifth chord tone is either raised or lowered (augmented or diminished), that universal stability is lost. An unstable triad may have one of the following:
A raised fifth:
A lowered fifth:
Using these unstable fifths, we can create triads by following these secrets:
Secret #1 – All augmented chords are like major chords.
An augmented chord is basically like a major chord with an augmented fifth (raised fifth). Let’s use a known major triad – C major…
…raising its fifth will yield:
So, if you raise the fifth of any known major triad, you’ll have an augmented triad. The augmented triad is just an unstable variation of the major triad.
Secret #2 – All diminished chords are like minor chords.
A diminished chord is basically like a minor chord with a diminished fifth (lowered fifth). C minor triad:
…if we go ahead and lower its fifth, it will yield:
If you are thinking what I’m thinking, you’ll see that lowering the fifth of any given minor triad will yield a diminished triad. The diminished triad is just an unstable variation of the minor triad.
Final Words
The two stable triads – major and minor – are commonly used because of their stability, while the two unstable triads – diminished and augmented are not so popular because of their instability (the diminished triad is tritonic).
The use of two popular triads does not overrule the fact that there are four triad qualities. The unstable triads certainly have their place in harmony. They come into the picture when there is need to interject a little tension and unpleasantness.
In subsequent posts, I’ll expand on these triad qualities and also give you a special cheat sheet prepared by our founder – Jermaine Griggs – that can help you play all triad qualities in all 12 keys.
Happy Holidays
P.S.
You will do well to join our list for HearandPlay 140 – Chords. For the first time in over fifteen years, we are offering you a resource ALL about chords from classification to construction, from application to alteration, and indeed everything you need to know about chords and harmonic structures. Check it out here.
Chuku Onyemachi
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