When approaching improvisation over an established harmony in any genre, it helps to sort out the types of chords you're dealing with. My approach is rooted in jazz theory, a heavy component of which is improvisation: knowing how to approach a given harmonic progression.
Players like Joe Pass and Jimmy Bruno like to reduce the number of different chords as much as possible. Watching Joe Pass's interviews and instructional videos chronologically reveals the following regression (not direct quotes):
- "Dere are five types of chords: major, minor, dominant, half diminished, and fully diminished."
- "Dere are tree types of chords: major, minor, and dominant."
- "Dere are two types of chords: major and minor."
Pat Martino is known to view every single chord type as a substitution for some other minor chord.
While I usually favor mental shortcuts, and the Pass/Bruno approach is perfect for beginners or for strictly tonal jazz standards, I fear it conflates too many distinct chord types.
I think most would agree with me that there are as many types of chords as you have different ways of dealing with them. That's the point of separating or combining chord types in the first place. However, you lose many harmonic nuances if you combine too much. For example, C6 and Cmaj7 are very similar. In most cases in jazz, they serve the same function. But my improvisational approach is slightly different with each. Over C6, I wouldn't hesitate to use the root, while I'd be careful with the 7. Over Cmaj7, I'd embrace the 7 and avoid the root.
So I came up with a list of chord types, partial to jazz, that cover the different ways I deal with chords. Each of these is still a parent category for more specific chord types, but I chose these because I didn't feel like anything is lost by dealing with every chord within each category in the same way.
The name of each category is the most basic chord type that usually falls into it. I include some other chord types and scales to give an idea of what each category entails.
- 6: 69, major triad
- maj7: maj7b5, maj13#11, Lydian
- 7: 13#11, Lydian Dominant
- 7sus: Mixolydian
- 7b9: 13b9, natural 5, symmetrical dominant
- 7alt: altered 5s and 9s, altered dominant
- m7: more ii than i, Dorian
- m6: tonic minor i, melodic minor
- m7b5: m9b5, Locrian Natural 2
- dim7: symmetrical diminished
I've been using this system in its current state for a couple years now, and it's served me well, but it isn't perfect. There are times when a chord falls into a different category than the way it's written. In less tonal, chromatic modal tunes (Shorter, Hancock, Evans), some chords won't fit any of these categories. Or I might drop the same chord into different categories at different times (or even within a single measure). It helps to view the above list as "ways to deal with chords" rather than "chord types".
I'll end with an example, a static Cm9 chord. I might start by using the "m7" category, using Dorian and minor pentatonic. For some contrast, I could move to the "m6" category, using melodic minor. For some outside tension, I might use the "m7b5" category, tweaking the ear a bit with Locrian Natural 2.
Stay tuned; I have another post prepared to elaborate on how I treat each of these categories.