[place]

Here is a progression that I recently came across:

| Cmaj7 D♭m7♭5 G♭7 | Cm7 F7 Bm7♭5 E7 | Am

I think the analysis of this is basically a I (Cmaj7) moving to VI (Am) that goes through a cycle of II-V chords in descending half steps. My question is why does this work? Is a constant structure thing or is there something else at work here?

Thanks in advance

OK.... an unofficial guess here.

That Cm7 is really a rootless... Ab9 chord.... thus you have a V to a flat-VI... sort of thing...

And that would be fine... except later on

The F-named chord goes to that B-natural-named chord.
(You would expect it to go to B-flat!!!.. yet it doesn't)

Just by saying the chord names outloud).... there is the detectable tritone goings on:

And then this deliberate tritone business carries on to its own logical resolution.

TIER

[place]

Thanks Tier, I appreciate your reply!

I see the cycle-5 motion G♭7 - B7 - E7 which then goes to Am, and I see that the B7 is replaced by its tritone F7 (I think this is what you were getting at). The question is what principle allows the delay of each resolution by inserting the II chord. Maybe it's interpellated II-V’s but I’m just not sure.

Okay, I guess that is what’s going on. The subV resolution just makes it harder to see. So the G♭7 would turn into a G♭m7 (II of E) but instead gets replaced by the Cm7 as part of the tritone substitution. It is like algebra!

Exciting stuff for sure. There are SO many possibilities.

[wmyette]

Hey Mark,

I would like to see more of the progression, but it might also be a modulation from C major to the relative minor of Am.

Most of the time you see chords moving by 4ths or fifths. Sometimes by 3rds. However, half-step motion (like this example) is also a smooth resolution.

I look at this as sub-V resolution with related ii's.

Original progression: | Cmaj7 D♭m7♭5 G♭7 | Cm7 F7 Bm7♭5 E7 | Am

So, for example, the progression without the minor chords is:

| Cmaj7 G♭7 | F7 E7 | Am

So the E7 is dominant resolution to the Am and the G♭, F are sub-V or tritone resolutions.

F7 = tritone sub for B7
G♭7 = tritone sub for C7

So, you could do this (depending on the melody):

Cmaj7 C7 | B7 E7 | Am or.... Cmaj7 C7 | B7 B♭7 | Am

Adding in the related ii's:

Cmaj7 G-7 C7 |F#-7 B7 F-7 B♭7 | Am

And round and round it goes. Basically the main rule of thumb is break down progressions to their most basic progression by isolating ii-V's and looking for dominant motion.

Hope this helps! Thanks for sharing and thanks Tier for your post too!

[place]

THANK YOU, Willie! I really appreciate the reply. It's a lot clearer now.

BTW it is a two measure intro to a song in the key of C major that begins on the vi chord A minor.