59. Secondary Dominants (2)

Last time, we analyzed the first half of "Fly Me to the Moon (In Other Words)" with secondary dominants in mind.

First, let's listen to that audio.

Chords only, simplified

Now that we've checked the audio, prepare the diatonic chords of the C major key with space between them, as in the image.
This time we'll work with four-note chords.

Let's check the important resolving motion from V to I.
In the figure above, it's the motion G7→Cmaj7.

To make it easier to hear, let's add a bass and tidy up the voicing.

V7→Imaj7: I changed this progression to V→I.

Of course, V7→I and so on are fine too.

This one has a stronger feeling of resolving brightly.
When you write your own music, use them as suits the song and the image you have in mind.

Next, let's apply the V→I resolving motion to the other diatonic chords as well.
The idea is to treat each diatonic chord other than Cmaj7 as a temporary I and add a V in front of it.

This is the result.
✳︎ Note: The voicings have been changed.

For analysis, I've labeled each chord with numbers like this.
✳︎ Note: Please be aware that these are different from slash chords (on-chords).

Let's write them into the "Fly Me to the Moon" score too.

As one way to read it, V7/II is "five-seven of two," in other words the V7 of II.
✳︎ The highlighted yellow part.

A7→Dm

A7→D

Let's check each V→I motion.
Keeping in mind that "this is a resolving motion," we'll listen in the order V7→I (four-note chords), V→I (triads), V7→I (triads).

V7/II

A7→Dm7

A→Dm

A7→Dm

V7/III

B7→Em7

B→Em

B7→Em

V7/IV

C7→Fmaj7

C→F

C7→F

V7/V

Next, let's check the 5th from the left, the first red circle.

D7→G7

D→G

D7→G

Moving to G gave a natural sense of resolution, but some of you may have felt something off you hadn't felt before when it moved to G7.
Let's check it once more.

D7→G7

If you look closely, it's a flow from a dominant 7th to a dominant 7th.
I'd like to cover this point in detail next time.

V7/VI

Next is a part you'll know well from around lessons 51 to 53 of Music Theory for Beginners.

E7→Am7

E→Am

E7→Am

Finally, let's check the 7th from the left, the red circle.

F#7→Bm7b5

F#→Bdim

F#7→Bdim

How was that?
You probably felt something far more off than with the 5th.
This motion is occasionally explained as a secondary dominant, but m7♭5 and dim chords are too unstable to serve as the I being resolved to, so it's common to consider that VIIdim and VIIm7♭5 basically have no secondary dominant.

Another difference to note is that the root note is outside the scale.
If the diatonic chords are family, think of the secondary dominants whose root notes are in the scale as relatives, and the one circled in blue, outside the scale, as a distant relative.

Next time, we'll explain and practice the parts that sounded off which we couldn't explain this time, as well as arrangements that bring secondary dominants into chord progressions we've seen so far.