As we continue our road-trip through the world of triads, we've hit the two most popular road-side attractions: major and minor triads. These two triad types are the most common triad types in rock, jazz and pop music. But there are two more, shall we say, exotic triads to look at. In this installment we'll look at the diminished triad.
The diminished triad is made up of two minor-third intervals which maps to the root, ♭3rd and ♭5th. In the key of A, a diminished triad is A (root), C (minor third) and E♭ (diminished fifth, hence the name).
Diminished triads sound pretty dissonant, compared to major and minor triads. In music theory terms, we say that the diminished triad sounds unstable. That triad doesn't sound like a satisfying stopping point. Psychologically, our brains want that triad to resolve to something else more stable. Here's a classic chord progression that includes a diminished chord:
The diminished triad is related to both the diminished triad and as well as the diminished scale. We'll tackle those topics soon enough. For now, get these shapes and sounds under your fingers. We have one more type of triad to look at, then we can begin to look at how chords are constructed and how to name them.