To enhance the basic blues, you can play seventh chords instead of just major triads. Dominant seventh chords are an essential ingredient to blues, gospel or jazz. To do this, the minor seventh is added to the notes of the major triad. This very ‘bluesy’ interval adds a lot more spice to the sound of the blues.
Here is the same blues in the key of F as in the example on blues basics, but this time played with dominant seventh chords. The F7 and G7 chords are played not in root position, but as inversions. This voice leading makes it easier for the right hand to move back and forth between the different chords.
Blues with seventh chords in the key of F
F7 LH 5 3 2 1 RH 1 2 3 5
Bb7 2nd inversion LH 5 3 2 1 RH 1 2 3 5
C7 2nd inversion LH 5 3 2 1 RH 1 2 3 5
Note that in bar 2 the IV chord (Bb) is played. This movement is very common in blues. Here is the twelve bar blues pattern with this new change.
I IV I I IV IV I I V IV I V
Or – written as notes in the key of F:
F Bb F F Bb Bb F F C Bb F C
The chord symbol for dominant seventh chords is dom7, or just 7. For example, Fdom7 and F7 denote the same chord.