Last lesson, we created a bass groove by doubling the kick drum pattern and used the notes of a D7 chord. We are going to expand on that groove today and learn how you can apply scale notes to your bass lines.
Today’s riff is based around an E7 chord. Although we are just playing along to drums, we still need a key centre and chords so the song can work with other instruments.
The tones of the chord should always be the framework you work around as it is the harmonic landscape of the tune.
As bass players, our functional role is to act as the connection between the rhythm and the harmony. We want to outline the chord progression while locking in with the drummer and reinforcing the necessary accents in the rhythm.
Let’s look at the notes in E7:
This is the arpeggio of E7 and the notes are E, G#, B and D. Learning a one-octave shape of this scale is important, but it does limit the notes we have available to us. To extend this shape, we can start an octave lower and play the arpeggio twice over two octaves.
Turning A Chord Into A Scale
Every chord we come across has a parent scale that the arpeggio is built from. For E7, it is the E Mixolydian scale. This is because E7 is the fifth chord in the key of A major and E Mixolydian is the mode built off of this scale degree.
E7 – E G# B D
E Mixolydian – E F# G# A B C# D
As an exercise, it is worth playing up and down the arpeggio and then up and down the scale to see how they relate to each other.
Extending The Mixolydian Scale
Like we did with the arpeggio, it is worth extending the E Mixolydian scale over two octaves to make it more useful for our bass line.
Adding Scale Notes To A Riff
Now we are familiar with the E7 arpeggio and the E Mixolydian scale, we need to know how to use them over an E7 chord. The arpeggio is fairly straight forward as there are only five notes and they will all work over the chord. With the scale, however, we need to be a bit more careful with when and where we place each tone.
The first thing to be aware of is the fact that the scale is made up of seven different notes, but only three of them are non-chord tones.
E F# G# A B C# D
The notes in red are in the chord of E7, so the only non-chord tones in the scale are F#, A and C#.
The 2nd, 4th and 6th (F#, A and C#), are the scale tones we want to use in our riff. However, we want to use them in passing and shouldn’t linger on them for long. They can be used for effect to create tension, but you should be in control of this know how to resolve it.
The next riff incorporates each of the three non-chord tones and shows how you can use them as individual notes for their own flavour.
Drum Backing Track