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·
Although everyone should get familiar with the tertian
and quartal major, minor and dominants and all the other
standard chords, the discussion of clusters (Steps
17,
18) should carry the clear message that
there are great opportunities for experimentation with
chordal and scale structures.
·
If you spend any time at all playing around with
clusters, or indeed chords of any sort, you'll quickly
realise that the keyboard isn't uniformly available
across its range for producing harmonious sounds. To
sound right, a chord has to be in the correct
register.
·
The further down the keyboard you go, the more widely
spaced the notes of a chord should be if they are to
sound clearly. As a general rule, for an instrument in
a decent state of tuning (and if the tuning's too far
out, some chord forms such as clustered quartal 13ths
will never sound right in any register) intervals closer
than about a fourth or fifth are not recommended lower
than the region around G below middle C,
unless a special effect is desired such as dark or
ominous atmospherics.
·
For clusters, there is a sweet spot beginning at G
below middle C (plus or minus a tone) and
extending upward. There is an upper limit because
beyond about G over middle C, the left
hand begins to intrude into the right hand's improvising
space.
·
So we see that the window for clusters is surprisingly
narrow - no more than about an octave - and it is one of
the important skills of keyboard harmony to be able to
organise the voicings of your chords in a way that keeps
the clusters in this optimal position.
·
To illustrate this,
Example
[19.1] a few choruses of accompaniment to a
blues in G, employing a range of tertian,
quartal, clustered and shell-voiced chords, organised so
that the dissonances cluster in the sweet spot.
·
So ends (except for some final thoughts in
Step 20)
this personal account of where jazz chords come from and
where they may be heading. There's still plenty of
exploration to be done, so what are you waiting for?
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