I particularly like chord progressions with key changes that are seamless. These take skill and imaginative craft because chords like to hang with their brethren in the same key, so if you introduce them to those from other keys without care and attention, it can get messy.
Cool multi-key chord progressions are a reminder of just how many options are available to writers who are not satisfied with the 3&4-chord turnarounds that fuel most pop, rock & blues. In these genres key changes are normal only used for effect e.g. it is common to move all of the chords temporarily to another key (a move by cheesy pop bands to milk the chorus) or to jump into another key for a tangential bridge (a move designed to create to break up the monotony).
Perfect Day is a great example of the cool variety, this created by Mick Ronson (on piano) for Lou Reed.
The first step in an analysis is to learn the progressions and listen carefully to how the chords resolve to one another. Once you get used to the changes then the sound of them will start to sink in more deeply.
Then write the chords as per each section:
Intro = F | Bbm | x2
Verse = Bbm | Eb | Ab | Db | Gb | Eb | F
Now write the keys (including Harmonic minor) of each chord as full triad scales. This is essential because in most sophisticated music the chords do not start on the tonic and often drift between keys:
The intro: F | Bbm | x2
F = F Gm Am Bb C Dm Edim
F’s relative is Dm and its Harmonic = Dm Edim F Gm A Bb C#dim
Bbm = Bbm Cdim Db Ebm Fm Gb Ab
Bbm Harmonic = Bbm Cdim Db Ebm F Gb Ab
Notice that only in Bbm Harmonic do the F and Bb triads appear = V Im
Now the verse: Bbm | Eb | Ab | Db | Gb | Eb | F
Bbm = Bbm Cdim Db Ebm Fm Gb Ab
Eb = Eb Fm Gm Ab Bb Cm Ddim
Ab = Ab Bbm Cm Db Eb Fm Gdim
Gb = Gb Abm Bbm Cb Db Ebm Fdim
Notice in Ab: the Bbm | Eb | Ab triads appear = iim | V | I
Notice in Gb: the Db | Gb triads appear = IV | I (or as a III | VI in Bbm).
Notice in Bbm Harmonic: the Ebm | F triads appear = ivm | V, resolving nicely back to Im = Bb when the verse starts again, except this Bbm is actually the iim of the key of Ab…
Alternatively the last to can be combined: Db | Gb | Ebm | F = III | VI | iv | V in Bbm Harmonic
With there being so many common chords between these keys its possible to produce a different analysis, but that’s part of the joy of listening to and studying ambiguous well-crafted music. This analysis is at least one of them and it gives serious music students an inkling into the deductive process required to approach all charts.
Once you have done this process many times (I recommend you buy a book of standards like the Real Book) you will start to remember which keys have which chords and what the Harmonic Minor (and Melodic) Scale does to the triads - see THEORY 3. You will also start recognise the changes by ear and since the famous songs like this are often referenced by other writers, the changes start to become familiar as well.
Here are the shapes I used:
If you are new to chord analysis but can read and/or play the clef using key signatures, then you will discover that the song is scored and played as if in Bb major = Bb Cm Dm Eb F Gm Adim, but this is just for convenience because obviously the chords do not conform.
I have just done the intro and verse. If you want to pursue it further then buy the piano chord sheet and keep on it.
