Some Thoughts on Dominant Sevenths.
Of all the chord types we use in jazz, by far the most
common are dominant seventh chords. They appear in every
standard chord sequence and feature in more modal type tunes
such as ‘Canteloupe Island’ and ‘Maiden Voyage’.
From the point of view of what to play over dominant
chords, it is worth knowing that sometimes dominants move in
mysterious ways, and that in certain circumstances some scale
choices are better than others
So let’s think about the way dominant seventh chords
function. The most common function of dominant chords is to
resolve to a chord whose root lies one step further round the
cycle, for instance in the ubiquitous II,V,I sequence. In this
case, my personal view is that ‘anything goes’ so we could list
our scale choices. By looking at the number of non-diatonic
notes within these scales, it is possible to compile the list in
order of ‘outsideness’.
Let’s consider the G7 chord in a Dm7 | G7 | C | chord
sequence.
Scale
G Mixolydian
Parent scale
C Major
Outside Sound
None
G7
G7sus4
Melodic 1
G7(#11)
G
Lydian
Dominant
G Mixolydian
b13
G Whole Tone
G
Spanish
Phrygian
G Diminished
G Altered
D
minor
C
Melodic 1
minor
2
C Harmonic 2
minor
3
Ab Melodic 4
G9(b13)
G7(#4#5)
G7(b9b13)
G13b9
G7 alt
or
minor
You’ll hear that the more non diatonic notes we introduce
the more tension is built up, which is then released when we
reach our C Major chord. I’ve found it valuable to work out
which notes in these dominant scales resolve up or down by a
semitone to notes of C Major.
Dominants move in mysterious ways.
You will often encounter dominant chords that don’t
resolve round the cycle.
You may hear some people,
particularly those classically trained, referring to these chords
as secondary dominants. In these cases, some scales will sound
better than others.
As a general rule of thumb, use the dominant scale that
contains the most notes that are diatonic to the next chord. A
good illustration of this is ‘Stella by Starlight’ (see attached
sheet).
 The A7 in bar 2 is an interesting case. My personal view
(and by the sound of it, that of Stan Getz) is that
diminished scale is best here. I think that Victor Young’s
original chord sequence was probably: Bb dim| % |Cm7 |
 The F7 in bar 4 becomes Fm7 in bar 5, so mixolydian is
good here.
 The Ab7 in bar 8 resolves up a tone to Bb. The Ab7 scale
choice that contains a Bb major triad is Ab Lydian
Dominant.
 Similarly, the Eb7 in bar 12 resolves up by a tone to
Fmajor therefore once again Eb Lydian Dominant is best
here.
 The G7#5 at the start of the bridge would suggest that
whole tone is a good choice, but beware!, - once you get
into the blowing, the pianist may view this as G7b13, in
which case a scale containing a b13 (e.g. Spanish
Phrygian or Altered) is best. – Use your ears.
 In bar 21, the Ab7 resolves up a tone to Bb as it did in bar
8, so the same applies.
All the other dominants resolve round the cycle, so anything
goes, though it’s worth saying that when resolving round the
cycle to a minor chord, a scale containing a b13 is often safest.
Summary
Here is a summary of dominant scale choices for dominant
seventh chords.
1. For dominant sevenths that resolve to a chord whose root
lies one step further round the cycle, anything goes. You’ll
probably find yourself gravitating towards particular
sounds you like, but check them all out.
2. On dominant sevenths that resolve up a tone, Lydian
Dominant is best.
3. Lydian dominant is also best for dominants built on II of
the key you’re in e.g. Take the A Train. It is also an
excellent choice for dominant chords built on IV of the key
you’re in. (e.g. bar 5 of a blues)
4. The final use for Lydian Dominant is where the dominant
chord resolves down by a semitone. This usually means on
tritone substitutions. (Lyd.Dom. is a tritone away from
Altered).
5. Some dominants resolve up a semitone e.g. bar 2 of ‘I
Remember You’ or bar 4 of ‘Groovin’ High’. In these
instances, altered or diminished are the best choices.
Don’t worry if this all seems a bit daunting at the
moment, there are a few years study in these few pages, but
I do feel that the acid test of whether someone really
understands functional harmony is their intelligent use of
dominant sounds.
Also, remember the chord tones (with the possible
exception of the 5th) remain the same, we’re merely playing
around with extensions which are the ‘colourful’ notes.
PC 2001
PC 2001