OK - the following is from Mark Sabatella's "Jazz Improvisation primer and this is the part that is explaining what I was trying to :
"Blues
The term "blues" is somewhat overloaded, describing a general style of music and a more specific category of chord progressions, as well as its colloquial meaning of a particular mood, as in the phrase "I've got the blues". The blues as a style has a rich history that is beyond the scope of this primer. The basic twelve bar blues form was mentioned earlier. In its original form, still played often in rock and R&B music, only three chords are used: the I chord, the IV chord, and the V chord. The basic blues progression is:
|| I | I | I | I | which, || F | F | F | F |
| IV | IV | I | I | in the key of F, | Bb | Bb | F | F |
| V | IV | I | I || yields: | C | Bb | F | F ||.
The chords are usually all played as dominant seventh chords, although they are not actually functioning as dominant chords in that they do not resolve to a tonic. The F blues scale can be played over this entire progression. While the blues progression can be played in any key, the most popular keys among jazz musicians seem to be F, Bb, and Eb, whereas rock musicians often prefer E, A, D, or G. This has a lot to do with the way instruments are tuned. Popular jazz instruments such as the trumpet and the various members of the saxophone family are usually tuned in Bb or Eb, meaning that the notated ``C'' played on these instruments actually sounds like a Bb or Eb respectively. Music written for these instruments is therefore transposed. The fingerings for the instruments favors playing in the key of C, which is actually Bb or Eb, depending on the instrument. Guitars tend to dominate rock music, and guitars are tuned to favor the keys containing sharps.
Playing the blues scale over the basic three chord blues progression in a jazz setting gets old very quickly. Starting around the swing era, and most notably in the bebop era, musicians began to make additions to this simple formula. One common adaptation of the blues progression, which is still considered the standard for jazz jam sessions, is:
|| F7 | Bb7 | F7 | F7 |
| Bb7 | Bb7 | F7 | D7alt |
| Gm7 | C7 | F7 | C7 |.
This progression offers a wider range of scale possibilities than does the basic three chord blues. For example, bars 8 and 9 form a V-i in G minor, and bars 9-11 form a ii-V-I in F.
The idea of adding ii-V's to the blues progression yields more variations. For example, consider:
|| F7 | Bb7 | F7 | Cm7 F7 |
| Bb7 | Bdim | F7 | Am7b5 D7alt |
| Gm7 | C7alt | F7 D7alt | Gm7 C7alt |.
This particular progression is especially common in bebop and later styles. Note the substitution of a Bb ii-V-I in bars 4-5, a G minor ii-V-i in bars 8-9, and a G minor V-i in bars 11-12. Also note the diminished chord in bar 6. This diminished chord is serving as a substitute for the dominant seventh, since both Bdim and Bb7b9 share the same Bb HW (B WH) diminished scale. This same substitution can be made for the second half of bar 2.
Other variations can be made using tritone substitutions. For example, Ab7 can be played instead of D7alt in the second half of bar 8. You can also change the qualities of the chords, for instance replacing that Ab7 with an Abm7. Another common substitution is A7alt for the F7 in bar 11. This substitution works because the chords share several notes, including the tonic, F, and because the A7alt forms part of a G minor II-V-i progression with the D7alt and Gm7 that follow.
Charlie Parker carried these types of substitutions to an extreme in "Blues For Alice". The chord progression in that tune is:
|| Fmaj7 | Em7b5 A7b9 | Dm7 G7 | Cm7 F7 |
| Bb7 | Bbm7 Eb7 | Am7 D7 | Abm7 Db7 |
| Gm7 | C7 | Fmaj7 D7alt | Gm7 C7 |.
This uses most of the techniques described above. You may wish to play with this progression for a while.
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"Blues
The term "blues" is somewhat overloaded, describing a general style of music and a more specific category of chord progressions, as well as its colloquial meaning of a particular mood, as in the phrase "I've got the blues". The blues as a style has a rich history that is beyond the scope of this primer. The basic twelve bar blues form was mentioned earlier. In its original form, still played often in rock and R&B music, only three chords are used: the I chord, the IV chord, and the V chord. The basic blues progression is:
|| I | I | I | I | which, || F | F | F | F |
| IV | IV | I | I | in the key of F, | Bb | Bb | F | F |
| V | IV | I | I || yields: | C | Bb | F | F ||.
The chords are usually all played as dominant seventh chords, although they are not actually functioning as dominant chords in that they do not resolve to a tonic. The F blues scale can be played over this entire progression. While the blues progression can be played in any key, the most popular keys among jazz musicians seem to be F, Bb, and Eb, whereas rock musicians often prefer E, A, D, or G. This has a lot to do with the way instruments are tuned. Popular jazz instruments such as the trumpet and the various members of the saxophone family are usually tuned in Bb or Eb, meaning that the notated ``C'' played on these instruments actually sounds like a Bb or Eb respectively. Music written for these instruments is therefore transposed. The fingerings for the instruments favors playing in the key of C, which is actually Bb or Eb, depending on the instrument. Guitars tend to dominate rock music, and guitars are tuned to favor the keys containing sharps.
Playing the blues scale over the basic three chord blues progression in a jazz setting gets old very quickly. Starting around the swing era, and most notably in the bebop era, musicians began to make additions to this simple formula. One common adaptation of the blues progression, which is still considered the standard for jazz jam sessions, is:
|| F7 | Bb7 | F7 | F7 |
| Bb7 | Bb7 | F7 | D7alt |
| Gm7 | C7 | F7 | C7 |.
This progression offers a wider range of scale possibilities than does the basic three chord blues. For example, bars 8 and 9 form a V-i in G minor, and bars 9-11 form a ii-V-I in F.
The idea of adding ii-V's to the blues progression yields more variations. For example, consider:
|| F7 | Bb7 | F7 | Cm7 F7 |
| Bb7 | Bdim | F7 | Am7b5 D7alt |
| Gm7 | C7alt | F7 D7alt | Gm7 C7alt |.
This particular progression is especially common in bebop and later styles. Note the substitution of a Bb ii-V-I in bars 4-5, a G minor ii-V-i in bars 8-9, and a G minor V-i in bars 11-12. Also note the diminished chord in bar 6. This diminished chord is serving as a substitute for the dominant seventh, since both Bdim and Bb7b9 share the same Bb HW (B WH) diminished scale. This same substitution can be made for the second half of bar 2.
Other variations can be made using tritone substitutions. For example, Ab7 can be played instead of D7alt in the second half of bar 8. You can also change the qualities of the chords, for instance replacing that Ab7 with an Abm7. Another common substitution is A7alt for the F7 in bar 11. This substitution works because the chords share several notes, including the tonic, F, and because the A7alt forms part of a G minor II-V-i progression with the D7alt and Gm7 that follow.
Charlie Parker carried these types of substitutions to an extreme in "Blues For Alice". The chord progression in that tune is:
|| Fmaj7 | Em7b5 A7b9 | Dm7 G7 | Cm7 F7 |
| Bb7 | Bbm7 Eb7 | Am7 D7 | Abm7 Db7 |
| Gm7 | C7 | Fmaj7 D7alt | Gm7 C7 |.
This uses most of the techniques described above. You may wish to play with this progression for a while.
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