You must Take the A Train…if you want to improvise over a standard. But this standard tune has a non-standard chord in Bars 3 and 4. If you are playing the “Real Book” version in C, the song starts with two measures of C Major 7, and then goes up a whole step to D. If we stayed in the Key of C, this would be a Dminor chord. Billy Strayhorn was much more creative than that, and he put in a chord rarely seen anywhere else: D7 b5.
The notes of this chord are D and F#, just as in the major chord, but the fifth is dropped from A to A flat. The Final note is the C.
Say we want to Bebop over this chord, and we need an 8 tone scale. What notes should we pick? The general rule is to keep the chord tones on the down beat, and get filler notes on the up beat. We also know that we are modulating from the C Major scale used in the first two measures, as well as the ii-V7-I progression that follows it. We can chose to stay as close to C as possible, as far from C as possible, or somewhere in the middle.
If we try to stay on the white notes in between we get
D E F# G Ab B C C#
Note that this give you a minor third leading in to the 7th. Thus, it sounds somewhat like a harmonic minor. This pattern is W W H H b3 H H H
To convert to my older post, rotate the minor third to the end:
H H H W W H H b3
THis is scale # 12
And over the chord:
Lets say we want to go as different as possible from that C Major scale, maintaining the Chord tones on the down beat. That gives us:
D Eb F# Gb Ab Bb C C# D
This pattern is H b3 H H W W H H
rotated to put the b3 at the end
H H W W H H H b3
It is scale #6
These two scales sound very similar, as we put a lot of restrictions on them. A Scale is constructed from 12 chromatic tones. 12 chose 8 means that only 4 notes are going to be skipped. The harder hitting chord tones mean that the chords are going to ring through the passing tones and give the same general effect.
This post was inspired by the this video: by Scott Paddock. One other scale he proposed is the Whole tone scale. A D Whole Tone Scale Looks like this:
D E F# G# A# C
It only has 6 distinct tones, not 7 like a major scale. It Also treats the F3 to G# (Enharmonically Ab from the chord) as a suspension as there are not any skipped tones between them. If we set that next to our first scale:
D E F# G# A# C
D E F# G Ab C C#
We see that we are missing the G natural but get the rest of the notes. If We Add the G natural and the C# to get 8 tones we have
D E F# G G# A# B C C#
Over the chords:
We could alternatively put the B natural in, but it means we lose the A#, which is part of the whole tone effect.
This is W W H H H H H H. I don’t see that in my list. We can fit that in to #42 in place of the duplicate I had there
We could also move the C natural to a passing tone and lose the C sharp.
This is W W W H H H H W which is scale # 35.
From an ease of playing perspective, I would probably keep with the first scale. It emphasizes the notes that are different from the C major, and it gets the minor third in there which is a great color.