Intervals: Seconds and Sevenths

We have one last stop on our journey studying intervals. Today we’re going to look at the final pair of intervals, seconds and sevenths. Once you have these terms, patterns and sounds down, they become the building blocks for triads, chords and arpeggios. Let’s dive in!

Seconds and sevenths each come in two flavors: major and minor. Remember that intervals are all named in relation to the major scale. So what we call a “second” is more specifically a major second. What we call a “seventh” is more specifically a major seventh. You may also hear people call these “flat seconds” or “flat sevenths”. If somebody refers to a second or seventh without a qualifier, you can assume that they mean the major kind.

Like the other pairs of intervals, seconds and sevenths share a similar tonal quality. Both are only a whole-step away from the root which makes them quite dissonant when played simultaneously with the root. But, just because it sounds dissonant, doesn’t mean you can’t make it sound musical. The main riff to Alice in Chains’ “Man In The Box” grooves righteously on a minor seventh:

Minor 7ths in action: Alice In Chains’ “Man In The Box”

Minor 7ths in action: Alice In Chains’ “Man In The Box”

Let’s start with the shapes for the major second. As usual, the tuning difference between the 2nd and 3rd strings give us a slightly different shape:

Major seconds shapes

Major seconds shapes

The minor second is a half-step smaller (one-fret) which, somewhat paradoxically, results in a wider stretch for your fingers:

Minor second shapes

Minor second shapes

Seconds are close enough that they can also be played on the same string:

Seconds played on the same string

Seconds played on the same string

The intervallic distance for sevenths is big enough that you’ll need to skip a string to play these. Remember the shapes for sixths? Same issue here. Here are the shapes for major sevenths:

Major seventh shapes

Major seventh shapes

Since a minor seventh is a half-step (one fret) smaller than a major seventh, the top note slides down one fret:

Minor seventh shapes

Minor seventh shapes

Now if we go down from the root note for sevenths on the same string, we get some very familiar looking shapes:

Sevenths played on the same string

Sevenths played on the same string

See? These distances look the same as the single-string intervals for seconds. It’s just a matter if which note you consider the root note. This is true of all of the intervals we’ve studied. It’s just that seconds and sevenths are the easiest to show.

Let’s look at how seconds and sevenths are related as inversions. First, let’s look at it based on music theory. Let’s trot out our handy-dandy A major scale chart:

A major scale chart

A major scale chart

The second degree of this scale is B. Now, let’s look at the B major scale:

B major scale chart

B major scale chart

The major seventh of B is A♯, which is a half-step higher than A. So if A♯ is the major seventh, A is the minor seventh of B.

Let’s look at how inversions work visually on the fretboard. First, let’s look at the relationship between major seconds and minor sevenths:

Inverting a major second into a minor seventh

Inverting a major second into a minor seventh

Inverting a minor seventh to a major second

Inverting a minor seventh to a major second

For minor seconds and major sevenths, the inversions look like this:

Inverting a minor second to a major seventh

Inverting a minor second to a major seventh

Inverting a major seventh to a minor second

Inverting a major seventh to a minor second

So we can now update our inversion chart to now include seconds and sevenths:

A visual display of inversions

A visual display of inversions

That wraps up our study of intervals. By themselves they may not seem all that special, but they are fundamental building blocks for triads, chords and arpeggios. Make sure that you understand these concepts before you continue your studies.

At first it will feel awkward to recall the names, the sound and the shapes of each interval type. But eventually those three separate aspects will synthesize into a single concept in your brain and under your fingers. One way you can help yourself groove these concepts is to start identifying them in your playing. Which things use fourths and fifths for maximum power? Which parts use thirds and sixths? Do you find any seconds and sevenths in what you play?

In the next installment, we’re going to look at triads, which are the foundation of chords and arpeggios. No matter what style you play, triads are an essential ingredient and powerful concept to master on the guitar. Before you can dive in, you need to have your intervals down.

Until next time, keep rocking!