Seventh scales (7th Scales) are basically descending mixolydian modes with added notes. The most common way of playing a 7th scales is to add the major 7th between the root and the flatted 7th scale degrees.
Adding this one notes gives you an 8 note scale which is important because it allows you, in this case, to start and end on the same note. This of course assumes you are playing 8th notes in a Bebop style.
As an example, let’s say we are playing a “C” 7th scale over a C7 chord and we are resolving to Fmaj7. If we are playing 8th notes and starting on the first beat of the bar we will end on the same note we start on. We start on a “C” note which means we will also end on a “C.” This is important because it allows us to end on the 5th of the Fmaj7 chord.
Now of course this is not all there is to 7th scales. It is possible to start on any note of the scale. Depending on which note we start on, chromatic notes are added in a way which ensures you will resolve nicely to your next chord. I will not go into every example in this post but will stick to just 2 examples for now. The first will be as described above and the second is as follows: Starting on the 3rd of the chord we will add chromatic notes between the 3rd and 2nd degrees, between the 2nd degree and the root of the chord and between the root of the chord and the flatted 7th degree. More information is also available in my book “Jazz Guitar Elements.”
A “C” 7th Scale (C Mixolydian with added note) is played over a C7 chord.
Next, let’s look at how we can use 7th scales over Half-Diminished chords. The first thing you should do is look at my post on “Chord Substitution.” In this post, we saw how a G9 chord with no root is the same as a Bm7(b5). If these 2 chords are in fact the same, then it stands to reason we can play a “G” 7th scale over a Bm7(b5) chord.
Here is an example of a “G” 7th scale used over a Bm7(b5) chord in a II – V – I chord progression in A minor.
Next let’s look at a standard. Below is a solo on the chord changes to “Stella By Starlight.” I’ve used 7th scales over some of the Dom7 and m7(b5) chords. At times I’ve used the entire scale and sometimes just fragments of the scale. (As in the first couple of notes only) Take a look and listen at how I’ve used 7th scales on both chord types. (Audio track is at the bottom of the post)
- John Roney:piano
- Dave Watts: bass
- Claude Lavergne: drums
- Michael Berard: guitar