Music Theory for Harmonica Players

Music Theory for Harmonica Players Part 10 – 7th Chords

In the last post we looked at how to build a chord and how we can refer to them based on their scale degrees. We examined the G (I), C (IV) and D (V) chords. In this post we’re going to extend these chords and turn them into 7th chords.

7th chords are extremely important in blues, folk and country music. They provide a great feeling of tension, and are perfect for leading into a chord change to make it sound more dramatic. Often blues tunes are made entirely of 7th chords.

Here’s the G scale again.

G Major Scale:         G A B C D E F# G
G Major Scale Degrees: 1 2 3 4 5 6 7  8/1

If you’re smart you may already be thinking that we can make a 7th chord by adding the 7th scale degree to the G major triad we looked at last time. You’d be correct… almost. In fact, we’re going to use a flat 7th. Chords with a flat 7th are so common that by convention when we refer to a 7th chord it’s assumed we technically mean a flat 7th chord. If we wanted to refer to a major 7th (where we don’t flat or sharp any of the notes) we would specifically say major 7th.

To make the 7th flat we simply move it down one semi-tone, or half step, relative to it’s position in the chromatic scale. The 7th note of the G major scale is F#, so the flat 7th is F. You already know how to play this note because you’ve memorised your C harmonica. It’s 2 draw whole step bend, 5 draw and 9 draw.

You can play a whole G7 chord by stretching your embouchure wide and playing draw holes 1, 2, 3, 4 and 5. This is actually the only 7th chord that’s available in it’s entirety in 2nd position.

Here’s the C Major scale again:

C Major Scale:         C D E F G A B C
C Major Scale Degrees: 1 2 3 4 5 6 7 8/1

The 7th note in the C major scale is B. If we flat B we get Bb, so that’s the note we want to add. We can play the Bb on holes 3 draw half step bend and hole 10 whole step blow bend.

Same thing for D, our V chord. Here’s the D Major scale again:

D Major Scale:         D E F# G A B C# D
D Major Scale Degrees: 1 2 3  4 5 6 7  8/1

If we flat the 7th in this D scale we get a C. We can play a C on blow holes 1, 4, 7 and 10. Lets add that to our diagram.

It’s well worth your time to memorise these three chords. It will pay off down the line.

Now we’ve learned the chords we need we’re ready to tackle a blues (yeah, I know, finally). That’s what the next post will cover.