Chords For Bass – Thirds Through A Scale

Creating Thirds From A Scale

The most common thirds are Major and Minor. Below we can see the major and minor thirds on C as harmonic intervals (Time: 0:17):

Even though a Major Scale is seen as being primarily Major, we have both major and minor thirds present within the scale itself. In fact, we have more minor intervals than major!

Let’s take the C major scale as an example (Time: 1:00):

C D E F G A B

To find a third interval within a scale, we select a note and then move up three notes in the scale.

• If we take the note C and move up three notes of the scale we find the note E. This is a major third interval. C to E
• If we take the note D and move up three notes of the scale we find the note F. This is a minor third interval: D to F

Repeating this process for every scale degree provides the following sequence of thirds:

• 1^st Degree: Major 3^rd
• 2^nd Degree: Minor 3^rd
• 3^rd Degree: Minor 3^rd
• 4^th Degree: Major 3^rd
• 5^th Degree: Major 3^rd
• 6^th Degree: Minor 3^rd
• 7^th Degree: Minor 3^rd

If we apply this sequence of thirds to the C major scale we find the following:

• C to E: Major 3^rd
• D to F: Minor 3^rd
• E to G: Minor 3^rd
• F to A: Major 3^rd
• G to B: Major 3^rd
• A to C: Minor 3^rd
• B to D: Minor 3^rd

Tip: Thirds on the 1^st, 4^th and 5^th scale degrees are all Major. All the rest are Minor.

We can apply this sequence to any major scale. So in the key of G major we have the following thirds:

• G to B: Major 3^rd
• A to C: Minor 3^rd
• B to D: Minor 3^rd
• C to E: Major 3^rd
• D to F#: Major 3^rd
• E to G: Minor 3^rd
• F# to A: Minor 3^rd

Bass Application

Now we know the sequence of thirds in a major scale let’s apply them to the bass. Below we have the basic set of thirds in C Major played with root notes on the A string (Time: 4:08):

Some of these thirds may sound a little muddy on that low string so let’s try the same sequence with root notes on the D string (Time: 5:25):

We can apply these thirds to any key. Here are some examples:

G Major (Time: 6:00)

F Major (Time: 6:23)

A Major (Time: 6:41)

Minor Scale Application

We can also apply this same principle to any type of scale. Every scale will have a unique sequence of thirds.

The Natural Minor scale would be as follows:

• 1^st Degree: Minor 3^rd
• 2^nd Degree: Minor 3^rd
• 3^rd Degree: Major 3^rd
• 4^th Degree: Minor 3^rd
• 5^th Degree: Minor 3^rd
• 6^th Degree: Major 3^rd
• 7^th Degree: Major 3^rd

Therefore, the thirds of the A Natural Minor Scale would be played as follows (Time: 7:43):

Melodic Application (Improvisation)

Once you’ve learned the order of thirds within the major scale you can start to play around with them a little by improvising chordal melodies.

The video lesson features the following example of improvisation (Time: 8:12):

 

Harmonization

When we play thirds around a scale in this way, we are, in effect, harmonizing a melody. The top note is our melody note.

Whenever you play any chordal piece on any instrument, it’s always worth paying attention to the upper most note. That will be the melody even when viewing the chord from a block chord harmony perspective.

As bass players we’re always thinking of the lowest note and building up from there. But in arranging and harmonisation, we see everything from the top down.