The Logic Off Topic list

Music Chick wrote:

>Does any one know any thing about the 12 bar blues.  what chords are used
please?

Hi Debbie,

There are many versions -- the most basic would be (In key of C)

C    F   C   C 
F     F   C   C
G(7)F  C  G(7)

These chords might be all simple major chords or all seventh chords
(dominant, minor7 or even MA7) or a mixture of the two with the G chords
most often being G7s. 

That is three four bar lines -- vocalists often repeat the same words on
each of the first two lines of each chorus add a following line that differs.

Often there is a turnaround of some kind at the end so that the last two
bars might be (still in the key of C)

C A7|D7 G7 

C Ami7|Dmi7 G7

These two  turnarounds have movement around the cycle of fifths to get back
to the first bar C of the next chorus. 

C Ami7|Abmi7 G7

C Eb7 D7 Db7

These last two are using chord substitutes (this is called tritone
substition) where a seventh chord three tones (6 semitones) away will
function as a substitute for another seventh chord.

This and other sorts of substition can be applied all the way through a
blues so that you might get two or even four different chords to the bar in
a slow jazz blues -- the V chord (G7) in the 9th bar is pretty essential to
the blues though.

Now you just gotta pay your dues ;-)

Regards,
M