Here is an interesting little chord study. We are all accustomed to thinking about the diatonic seventh chords played in an ascending numerical order of I, ii, iii, IV, V, vi, vii. How about playing an ascending numerical order but with a descending note order? In this example I begin with a root position tonic major seventh chord and move through the entire diatonic set of seventh chords in a major scale by keeping one common tone and moving the remaining three voices down by step to the next available chord tone. For example when moving from tonic (I) to supertonic (ii):
CMaj7 (voiced as C-G-B-E) moves to Dm7 (voiced C-F-A-D).
“C” is the common tone and the remaining three voices descend by step.
When moving from supertonic (ii) to mediant (iii):
Dm7 (voiced C-F-A-D) moves to Em7 (voiced B-E-G-D).
“D” is the common tone and the remaining three voices descend by step.
We continue this pattern until we return to tonic but this time it ends up in first inversion (E or third in the bass) at end of line one.
Line two begins with this tonic in first inversion and descends through the set of diatonic seventh chords as we did in line one; keeping the common tone and moving the remaining three voices down by step. Now we end up with a tonic chord in second inversion (G or fifth in the bass) at end of line two.
Line three begins with this second inversion tonic chord and moves through the series as above ending with a third inversion tonic chord (B or seventh in the bass) at end of line three.
Line four begins with this third inversion tonic chord and moves through the series again ending up where we started with a root position tonic chord.
Just in case you are not familiar with figured bass, the numbers next to the Roman numerals refer to the intervals above the bass note and is another way of indicating chord inversions. The following may be helpful:
Root position = 7
First inversion = 6/5 (third in bass)
Second inversion = 4/3 (fifth in bass)
Third inversion = 4/2 (seventh in bass)
What we end up with is a little exercise in which we play all of the diatonic seventh chords found in a major scale in all the possible inversions. This is not the only way to accomplish this but I thought it was interesting to do them in this descending note order for a change. I didn't even know it was possible until I tried it.
Also notice the interesting inversion pattern that occurs with the different seventh chords in the series:
Root position – Third inversion – Second inversion – First inversion.
This pattern repeats through the entire example.
You can also read down each column and play each of the four voicings (root position, first, second and third inversions) for each diatonic seventh chord.
I hope you find this as interesting as I did. Try using this pattern on other string sets, although some of the voicings become difficult to play.
Remember you can recycle most of these voicings as rootless ninth chords.