Date: Tue, 11 Dec 2001 08:55:31 -0800 (PST) From: Winslow Yerxa Subject: Re: blue notes/jazz substitutions - the tritone substitution
Glenn Weiser writes:
>That raises another intersting question: playing over >jazz chord substitions for 12-bar blues. But I don't >that much jazz, so, maybe someone could list some of >the more common substiutions, either in C or by Roman >numeral . You got anything on this?
Let's look at tritone substitutions.
The absolute simplest substitution, and fairly common, would be to use a tritone substitution on the way from I to IV:
I bV9 IV9
e.g. C Gb9 F9
Here the bV chord is a tritone substitution for I, and it also slides down to the IV by a semitone. Using 9th chords seems to make it that much more lubricious.
Another one you sometimes hear is a vamp, on a long stretch of I before the chord changes to IV. It helps to keep things from getting monotonous, especially on tunes where the initial I section has been doubled or quadrupled in length. At a slow walking tempo, you play 3 beats of I, then on the last beat, you play bII, leading back to I on the first beat of the next bar.
(slashes = additional beats of the same chord)
I / / bII | I / / bII (etc. - 1 beat per chord)
e.g. C C C Db | C C C Db (etc.)
Again, using 9th chords can fill this out.
Now the Db does not normally occur in the key of C. But it leads so nicely into the C, and doesn't seem to disrupt the tonality despite its foreign nature. It serves the same function of putting a little V chord in the same place - adding harmonic movement (but not too much) and leading strongly back to the main "focus" chord. In that sense, it can be viewed as a tritone substitution for V.
Another I'm not sure I've heard but which I can hear working would come in the last third of a 12-bar progression.
(slashes = beats)
V / / / | IV / / / | I etc.
becomes
V / / / | IV / / VII| I etc.
e.g. G / / / | F / / B | C etc.
Here, at the end of the IV chord, we've inserted a tritone substitution for the IV chord, which leads up to the I chord by a semitone. You could do the same thing leading back from te IV to the I earlier in the tune, at the end of Bar 6.
Winslow
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