In part 3 we’re going to look at how to play triads on the bass. Triads are simple three note chords that form a foundation for a lot of extended harmony. Before we can go on to explore chord extensions it’s really important to understand triads.
There are essentially four types of triad, these are major, minor, diminished and augmented and they are written out here in Example 1. In this example all the triads have the root note C.
We can harmonise scales into triads. In part one we harmonised scales into intervals of a third and a triad is two intervals of a third stacked together, by which I mean you take a root note find a note that is a third above it and then another note which is a third above again. The three notes of a triad are often referred to as the root, the third(an interval of a third above the root) and the fifth (an interval of a third above the third and an interval of a fifth above the root). You will find that when you harmonise a major scale into triads you’ll get seven chords, three major triads (chords I, IV & V), three minor triads (chords II, III and VI) and one diminished triad (chord VII). Example 2 is a G major scale harmonised into triads played in root position (the root note is the lowest of the three notes).
In the previous example we refer to these triads as root position because we’ve arranged each triad in a neatly stacked order with the root at the bottom and the third and the fifth stacked on top of it. If we change the order of these notes to make either the third or the fifth the lowest note then we have what we call an “Inversion”. There are only two possible ways to invert a triad. The first way is to put the third at the bottom as in Example 3.
If you harmonise a melodic minor scale into triads you get two minor triads, two major triads, two diminished triads and one augmented triad. Example 7 is a G melodic minor scale harmonised using root position triads.