When you want to play altered jazz guitar lines over a dominant 7th chord, there is an easy and efficient option that is to play a major triad starting on the #11 of the chord you want to improvise over. This way you highlight the b7, #11 and b9 and add tension to your playing.
Let's take an example with a II-V-I sequence in the key of C major. The progression is Dm7 | G7alt | CMaj7.
The first thing to do before starting exploring the twelve different scales shown in this lesson is to understand how to build a basic dominant 7th chord and what its role is.
What's a Dominant 7 Chord?
A Dominant 7th chord is made up of a root / tonic (1), a major third (3), a perfect fifth (5) and minor seventh (b7). It is one of the most versatile chords. It is considered as a major chord because of the major third (3).
Indeed, the 3rd tell us if the chord is minor or major. The minor seventh (b7) indicates whether the sound wants to move or not (resolve) to another chord. Usually dominant chords tend to resolve to a chord down a perfect fifth (or a chord up a perfect fourth).
C Dominant 7th Chord C E G Bb Intervals 1 3 5 b7 Related Arpeggio 1 3 5 b7