Secondary Dominant ① / Music Theory Lesson

Chord Progressions with Non-Diatonic Chords

We will use our knowledge up until this point to the fullest to take a look at a chord progression that uses non-diatonic chords.

“Fly Me to the Moon (In Other Words)” will continue to be used for this tutorial.

Here, lets take a look at the chords.

The chords sound like this:

On the piano roll it looks like so:

Lets write it the degree names into the piano roll.

Lets find the non-diatonic chord point from the chords above.
This time we will be analyzing in the key of C major.

It will be any chord not found in the boxed area above.

The C7, E7, and A7 are non-diatonic chords.

Why don’t we try to change these chords with diatonic chords?
We’ve changed the chords boxed above to:

• C7→Cmaj7
• E7→Em7
• A7→Am7

It will look like so.
Lets hear how this sounds.

Before changing the chord progression:

After changing to diatonic chords:

What did you think?
There is a huge change in the feel of the song.

As expected, the non-diatonic chords (C7, E7, A7) have a much stronger tension and pull towards the next chord that follows it.
Lets think back to the info from our last article.

First we have the chord progression using just diatonic chords in C major.

We’ve changed the “IIIm→III” and “IIm→II” as shown below:

It has the same melody but it sounds much different.
The V→ to Im (III→VIm) contains the leading tone from the scale of the relative key (A minor in this case).

The last (D→G) II→V area is the V→I in the key of G major.

With this in mind lets take a look at the “C7 E7 A7” from the chord progression in “Fly Me to the Moon (In Other Words)” and focus on the “following chord” that comes after each dominant chord as well.

C7→Fmaj7 is V7→Imaj7 in Key=F

E7→Am7 is　V7→Im7 in Key=A minor

A7→Dm7 is V７→Im7 in Key=D minor

We can consider it like so.

We’ve basically changed the triads from last time to 7th chords.
Because it contains the tritone, it has a stronger sense of tension and urge to resolve.

Temporary Modulation

This kind of temporary change in the key can be considered a temporary modulation.

The “C7→Fmaj7 = V7→Imaj7 in Key=F” is

It feels as is the song in the Key=C Major (or A minor) suddenly changed to the Key=F momentarily.
With this in mind, we will take a deeper look at this in our next article.

Article Writer: Kazuma Itoh

After moving to the USA at 18 years of age with a scholarship from Berklee, he completed a 4 year study focused on song writing and arranging there.
Using this knowledge, he works across a variety of fields from pop music, film music, and more.

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