Learn to improvise. 2003-2004. Lesson 18: diminished chords.
For improvisation thinking in structure helps: 1) what is the initial key,
2) which are the successive temporary keys, 3) which are the chords.
It is practical to consider the chord structure to consist exclusively of
major and minor chords. You can object, that particularly the complex
chords (C9+, Cmaj7-5, etc) form the essence of a certain music
piece, but still, if you are able to discover a simplified underlying
harmonic flow, it will help to keep the thread of the music. Compare the
plot of a story.
Together with the primary chords major and minor we also mentioned
the diminished and augmented chords. The reason is, they consist of
two thirds and are consequently fundamental.
The diminished chords
deserve extra attention. If a diminished chord belongs to the basic
harmonic flow it is hard to find an acceptable replacement for it among
the major and minor chords. An example is the following chord scheme:
C Cdim C Cdim C A7 Dm G7...
Hear this scheme.
The name diminished refers to the fifth (Cdim has c to g-flat in stead of
c to g). On the one hand it seems logically to talk of C-minor-
diminished (Cmdim), as the first interval is a minor third (c to e-flat), on
the other hand however one may say both intervals are diminished.
The case is even stranger, because for improvisation Cdim is used as a
replacement for Cdim, Ebdim, Gbdim en Adim. Only a connoisseur will
be disturbed by the difference. Hear the previous chord scheme, but
with Cdim replaced by Cdim7.
Hear previous scheme with dim7 in stead of dim.
In practice it is convenient to have to take into account only 3 different
dim7 chords in stead of 12 dim chords. It has become so established,
one mostly writes only dim even if dim7 is meant.
The word 'seventh' is strange too, because in C7 the seventh note is b-
flat and in Cdim7 it is the a. As an excuse one can count along the
diminished scale, which consists of alternately one and two key steps.
Then the seventh note is the a. All these remarkable things are also an
indication of the application of the diminished chords. Their effect,
namely, happens to be a little strange, too.
Typical applications for the diminished seventh chord are the following:
-Nearly every seventh chord may be replaced by the diminished seventh
that has 3 of the 4 notes collective. It gives the strange (often
interesting) effect, though. It depends on the music style how often you
can use it. For bar music e.g. it may be applied much.
Compare scheme Em B7 with Em Ebdim7.
-Interlude during a modulation. Suppose, you have played a song in A,
but the singer prefers G. Then you will modulate to G, as soon as the
singer starts, but in order make the changing more flowing, you may
play Adim7 in between.
Modulation of key A to key G via Adim7.
-For just an interesting effect. E.g. by replacing the chord Cm with
Gdim7 in the scheme G G7 C Cm G D7 G of 'When the saints go
marching in' (in G). It is incorrect, but funny.
'The Saints' normal and with Gdim7 as a replacement for Cm.
-Emergency chord if you don't know the real one. Often it works well.
You have to play something anyway. A dim7 chord may be interpreted
as improvised on purpose in stead of incorrect. Moreover, the chance to
strike the best fit is 1 out of 3 for a diminished seventh chord, while it is
1 out 24 for the right major or minor chord.
-If it is meant in the composition. E.g. the 2nd chord in 'Stormy
Weather' (Scheme: G G#dim7 Am D7).
Hear the effect of the chord dim7.
The real diminished chord with 3 notes is not used much in
improvisation. It is too delicate. E.g. the difference between the
positions c e-flat g-flat and e-flat g-flat c is more sensitive than between
the positions c e-flat g-flat a and e-flat g-flat a c.
The position has more influence for dim than for dim7.
Use dim7 chords. Work playfully with them. Hear the typical atmosphere
and get used to it. Play them broken (e.g. like in the Moonlight Serenade
of Beethoven) and make melodies with them.
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