Tonic, Subdominant and Dominant Chords

Let’s go on to the way chords are formed and how to use them in bluegrass music.

A “Triad” consists of three notes. A triad formed on the “home” note of a chord is a “root position” triad. In the key of G major, a root position triad consists of the three notes: G B D. If you refer to the G scale, (GABCDEF#G) you will see that the major triad is based on two intervals; one constructed with a major third on the bottom and the other a minor third on the top. The major third is figured: G to A is a whole-step and A to B is a whole-step. Thus, two whole-steps make a major third. The top third – the minor triad- is formed by the interval B to C, one half-step, followed by the interval C to D, a whole-step.
To review: A major third with a minor third on top is a major triad and a minor third with a major third on top is called a minor triad. So then, a G chord is built by the notes G B D and a G Minor chord is G Bb D.

In bluegrass, many of the tunes and songs are constructed using the 1, 4 & 5 chords. Again, think of the G major scale. GABCDEF#G. The G is the 1 chord, the C is the 4 chord and the D is the 5 chord.
The key a piece of music is written or played in is called the root or “Tonic” chord. The 4th chord is called the “subdominant” and the 5th chord the “dominant”.
The subdominant root position triad in the key of G is formed on the 4th note of the G scale which is C. Looking at the G scale again, (GABCDEF#G) we see that if we start on a C note and build a lower half using two whole-steps, we’ll need to use these notes: C & E (C to D is one whole-step and D to E is another whole-step). Then for the top of the triad, we’ll need a G (E to F is a half-step and F to G is a whole step). Our C chord, in its’ root position will be CEG.
The dominant chord in its’ root position will be the three notes: D, F# and A.

Key of G:
G chord G B D
C chord C E G
D chord D F# A

Key of C:
C chord C E G
F chord F A C
G chord G B D

Try building the following chords all in their root position using triads:

Key of D:
Key of A
Key of F

Now build a C Minor root position triad.