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Dominant 7th chords (V7) are those chords built on the 5th degree of the scale. Their formula is therefore (R, 3, 5, b7). For example, in C major, we have G7 = (G, B, D, F).
This chord contains a very dissonant and unstable #4/b5 interval called “tritone” (because it consists of 3 whole tones). That tritone always sits between the third and the seventh of the chord. For G7, the tritone is between B and F.
This tension needs to be released (except in a blues!), so the V7 chord needs to resolve somehow to a more stable chord. Very often (but not necessarily) that chord is the I chord (or i chord); this then is the so-called “perfect cadence”. In C major that would be G7 -> C; in C minor it would be G7 -> Cm.
We will limit the discussion to major keys.In the C major scale, the note B is the leading tone so it resolves upward to the tonic, whereas the note F is the subdominant which is strongly pulled downward by the (stable) mediant (the 3rd scale degree E).
When you improvise, you can of course use the chord arpeggio and resolve as indicated above. But that quickly becomes a tad limited. So, what are the options?
1. Chord tensions
If you remember my post about chord tensions, you know that the only “avoid notes” on a V7 chord are the notes a semitone above the chordal 3rd and 7th. For G7, those notes are C (11) and F# (7). All the other notes are available tensions. (Avoid notes are not forbidden; you can certainly use them as non-essential notes, but you should never insist on them).So, for G7, we have:
G {Ab A A#} B (C) C# D {D# E} F (F#), or equivalently R {b9 9 #9} 3 (11) #11 5 {b13 13} b7 (7)
The available tension notes are: b9, 9, #9, #11, b13, 13
(We are talking about non-altered V7 chords here, i.e. the 5th of the chord is natural. Altered V7 chords have a #5 or a b5 and are dealt with differently).Since we are in C major (the cadence is G7 -> C), we need to understand how these tension notes behave in the key of C major. Put differently: where are these notes going?
– The b9 (Ab) has a very strong tendency to resolve downward to G; G is the root of the G7 chord, and the 5th scale degree in C major. So the resolution is straightforward.
– The 9 (A) also has a tendency to resolve downward to G, although less so than Ab.
– The #9 (A#) has a very strong tendency to resolve upward to B; B is the third of the G7 chord and the leading tone of the C major key. How you handle this is up to you. Resolving to B over the G7 chord is obviously straightforward. Resolving to B over the C major chord will create a Cmaj7 chord which may or may not sound appropriate (it will depend on your personal taste and the musical context).
– The #11 (C#) has a very strong tendency to resolve upward to D; D is the 5th of the G7 chord and the supertonic (degree 2) of the C major scale. Again, resolving over the G7 chord is easy; resolving over the C chord may require an additional resolution to C because ending on a Cadd9 chord may or may not not be appropriate.
– The b13 (Eb) behaves exactly like the #11
– The 13 (E) also behaves like the #11 and the b13
2. The pentatonic options
If you are a die hard pentatonic player, you should know what impact the various pentatonic scale tones will have on the V7 chord.2.1 Playing the minor pentatonic of the key
The scale is: C Eb F G Bb, which we rewrite G Bb C Eb F to get a G7 chord skeleton. As you can see, we have T b3 (11) b13 b7
So, if you play this scale, you need to be careful with the C (11) which is an avoid note. Also, the b3 against the 3 of the chord will produce a bluesy sound that you may or may not want in the current musical context.2.2 Playing the major pentatonic of the key
The scale is: C D E G A, which we rewrite G A C D E or equivalently T 9 (11) 5 13.
Again, you need to watch for that 11.2.3 Playing the minor pentatonic of the chord
The scale is G Bb C D F or T b3 11 5 b7. Here again you should be careful with the b3 and the 11.2.4 Playing the major pentatonic of the chord
The scale is G A B D E or T 9 3 5 13. This is very safe, but maybe not very original!3. Yet another option: the Lydian dominant scale
The “Lydian dominant” scale is a Mixolydian scale with a #11: T 2 3 #4 5 6 b7. It is sometimes called “Mixolydian #11”!
For a G7 chord, we get G A B C# D E F.Where does this beast come from, you may ask?
This scale is usually defined as the 4th mode of the melodic minor scale; the D melodic minor scale is D E F G A B C#. The 4th mode off this scale is G A B C# D E F.In terms of chord tones we have R 9 3 #11 5 13 b7.
As you can see, this scale is perfectly safe to use over V7 since it doesn’t contain the 11. The #11 provides a powerful resolution discussed above, and so does the 13.
For many guitarists, the Lydian dominant scale is the de facto go to scale to create phrases on a V7 chord resolving to I.Also, the D melodic minor scale is very convenient over a Dm -> G7 -> C cadence since the first part of the scale (D E F G A) spells a Dm chord whereas the second part (G A B C# D) spells a G7 chord. So, in general, to improvise over a ii -> V7 -> I cadence you can always use the melodic minor scale built on the 2nd scale degree!
Conclusion
Knowing how to best resolve V7 chords is an essential way to improvise more meaningfully (melodically). We obtain this understanding by looking at the natural tendency of chord tones and tension notes in the given key.
Enjoy! -
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