Today we continue our discussion of secondary dominants with a look at the VI7 chord. Remember the magnetic tunnel progression? The power of that progression came from the fact that we were moving from the v of V to the V of I to the I (ii-V-I).
That sequence can be extended to the v of ii, which is vi. Try playing vi-ii-V-I to see what I mean (in the key of C major, that’s Am-Dm-G-C). It makes sense to think of this as an extended tunnel sequence. Can you feel the smooth and direct motion, and the sense of inevitability when you finally return home?
Today we are going to use this extended tunnel sequence as a jumping-off point in order to introduce our next secondary dominant. Recall that we can journey to another harmonic world by replacing the ii with the II7. II7 is the V7 of V, and pulls us as forcefully to the V as the V pulls us to the I.
We can achieve a similar effect by bringing in the V of ii. Say you want to emphasize the ii, making it feel like a temporary home in your song. Simply play the VI7 immediately before it (VI7-ii in the Key of C is A7-Dm). It will function as a portal to the ii just as the II7 functioned as a portal to the V.
That’s useful on its own, but for today’s exercise I’m going to show how the VI7 can add new life to the vi-ii-V-I.
Today’s exercise is a bit simpler than usual. That’s because we’re going to be playing a set chord cycle over and over. The purpose of this exercise is to develop a feel for the place secondary dominants can play in your songs.
Start out by playing the following progression and coming up with a corresponding melody: VI7-ii-V-I (in the key of C: A7-Dm-G-C).
Once you’ve got this tunnel sequence down, it’s time to add another part. Follow it with this sequence: vi-IV-V-iii (in the key of C: Am-F-G-Em).
Now play the entire sequence through, giving equal time to each chord: VI7-ii-V-I-vi-IV-V-iii (in the key of C: A7-Dm-G-C-Am-F-G-Em).
Try to come up with a melody to match the progression. Treat the first four chords as a question and the second four chords as an answer. Interpret that however you like. Somehow the first four chords should be setting the tone and the second answering or developing it.
“BUT THIS IS YOUR PROGRESSION, NOT MINE!”
Normally, these exercises are designed to help you come up with your own progressions. So why am I giving such rigid instructions this time?
Because this chord cycle illustrates a number of useful ideas:
The appearance of the vi chord here is unusually interesting because you’ve already introduced the VI7. It adds character to an otherwise ordinary move (the change from I to vi is a common way to change mood).
Switching between the major and minor versions of a chord can generally be an interesting exercise. Experiment with it!
The IV-V-iii at the end is a surprising move. IV-V often leads to I. The iii seems all the more colorful if it appears instead.
The return from iii-VI7 foreshadows our next installment in this series. That’s because iii is the v of VI.
On the last point, what this means is that we’ve extended our tunnel sequence by one more step. Now it’s iii-VI7-ii-V-I.
That’s not all: iii feels like the end of the sequence and VI7 the beginning. We’re establishing our home key in an unusually roundabout way! The I only shows up in the middle.
The lesson? Even though I’ve given you a rigid exercise, the ideas it illustrates can form the basis of a great deal of experimentation. Get to it!