The Major's Bass Boot Camp - Session 18

[Major-Minor]

The Major's Bass Boot Camp - Session 18

The Development of the "12 Bar Blues" in the Jazz Genre

(I'll be doing a more "Rhythm and Blues" and "Rock" oriented Session on Blues riffs and Lines sometime soon.)
(SEE SESSION 19 "12 BAR BLUES - BASS RIFFS AND LINES")

With this set of examples, I hope to show you how the basic blues sequence (as used in Urban Blues and 50's Rock and Roll) developed into the more complex "jazz" blues sequence which you will encounter on virtually every jazz gig. When the band can't settle on a tune to play next, the usual cry is "… well I suppose we could always play a Blues ! ".
There are lots of jazz tunes that have been written for this 12 bar sequence and usually the frontline players can agree on one they all know. As a bass player, all you really need to know is the key. And this is usually in horn-friendly keys like F or Bb. Rock oriented guitarists usually want a Blues in E or A, but that would put the transposing instruments into awkward keys like F# or B.

So I've chosen the key of F for this Session.
I've restricted all the bass parts to notes within the 1st two positions.

MBBC18a
[attachment=45609:MBBC18a.pdf]
[attachment=45613:MBBC18a.mp3]

So, here we have the basic blues chord sequence as used in 50's Rock and Roll.
In the first "chorus" (in jazz, this term means one full sequence - in this case 12 bars), I've just used Major triads (no dominant 7ths). As you can see, there are only 3 chords (hence the phrase "Three Chord Trick") - F, Bb and C - the Major triads that are built on the 1st, 4th and 5th notes of the F major scale.

In the 2nd chorus, I've added the 6th note of the F scale to the bass line, so in bar 13, you can see a D on the 4th beat. This note has a benign effect on the harmony. It is, after all, the relative minor root of F major (D minor).
Similarly in bar 17 there is a G in the Bb major bass line, G being the 6th note of the Bb major scale.

In Chorus 3 (from bar 25), you will see and hear "Dominant 7th" chords. Notice how the nature of the sound changes. Now much more unstable and edgy. So in the bass line we get the root, 3rd, 5th, 6th and now also the flattened (dominant) 7th.
This is the archetypal Rock and Roll bass line.

Chorus 4 (from bar 37) - here I've written some variations on this bass line, still using the same notes, just in a different order.

MBBC18b
[attachment=45610:MBBC18b.pdf]
[attachment=45614:MBBC18b.mp3]

Now we start to get into the variations on the sequence that have become standard in the jazz genre.
Each of the 4 chorus's in this example demonstrate a development away from the original 3 chord blues sequence.
So in Chorus 1 (which is still just Dominant 7 chords) we get the following alterations (substitutions):
Bar 2 now becomes Bb7 (chord Ⅳ - also called the subdominant)
Bar 8 now becomes D7 (a dom 7 chord built on the 6th degree of the F scale - the submediant)
Bar 9 becomes G7 (a dom 7 chord built on the 2nd degree - the supertonic)
Bar 10 becomes C7 (chord Ⅴ - the dominant)
Can you spot the cycle of 5ths from bars 8 to 10 ? D7 G7 C7
Now for the last 2 bars of the sequence we get another cycle of 5ths :
A7 D7 G7 C7 (F7)

Chorus 2. Here I have added some " Ⅱ Ⅴ Ⅰ " sequences. Look at bar 16 for example:
Where before we just had an F7 chord leading into Bb7 in the next bar, we now have 2 chords - Cm7 and F7. So by inserting the Cm7 we get Ⅱ Ⅴ Ⅰ in the key of Bb.
Confused ?
This is one of the most crucial points to get your head around. Although we say a piece is in such and such a key, actually most music is constantly changing key within its internal structure. Wherever you get a dominant 7 chord, effectively you are moving into the key of which that chord is "dominant" even if only fleetingly.
Bar 16 is a good example of this:
Think for the moment of bar 17 as being in the key of Bb. The 2nd and 5th degrees in Bb major are C and F, and because of the key signature of Bb (2 flats - Bb and Eb) if we build a 4 note chord on C we get C Eb G Bb (Cm7). On F we get F A C Eb (F7).
So these 2 chords - Cm7 and F7 lead us into the "new" key of Bb. Of course, when we get to the Bb, we have put that flattened 7th (Ab) into this chord making it into Bb7, so this chord in turn becomes a dominant chord in the key of Eb major.
So the instability continues, and rather than moving to Eb major, we return to our home key of F major.
We get the same Ⅱ Ⅴ Ⅰ effect at bar 20 (Am7 D7) bars 21 and 22 (Gm7 C7) and again at 23 (Am7 D7) and 24 (Gm7 C7).

The other substitution in Chorus 2 is in bar 18. Here the bass note is crucial. The original chord was Bb7 (Bb D F Ab). Now we have B diminished (Bdim) - B D F Ab
You will see that 3 notes are common to both chords - D F Ab - only the Bb bass note changes to B natural.

Chorus 3.(from bar 25). Here I have changed all the Minor 7th chords to♭5s (flat 5s) so in bar 28, the Cm7 is now changed to Cm7♭5. In bar 32, you will see that the bass line reflects this change: For the 2 beats of the Am7♭5 I have written A (the root) and E♭(the flattened 5th). And in bar 33, all the notes of Gm7♭5 are present in the bass line : G (root) F (minor 7th) Db (♭5) and Bb (minor 3rd).

Chorus 4 (from bar 37): More substitutions: B diminished (B dim) in bar 38. And a descending line of Dominant 7th chords in bars 43 and 44: F7 E7 Eb7 D7.

MBBC18c
[attachment=45611:MBBC18c.pdf]
[attachment=45615:MBBC18c.mp3]

In this example, I've introduced passing notes into the bass line i.e. non-chordal notes and I've used even more substitutions.
Look at the 2 chords in bar 1:
F7 = F (root) A (major 3rd) C (5th) Eb (7th)
B7♭5 = B (root)D# (major 3rd) F (flat 5) A (7th)
Now let's look at the notes of B7♭5 in a different order:
F (flat 5) A (7th) B (root) D# (major 3rd)
and let's think or the D# as it's enharmonic Eb:
F (flat 5) A (7th) B (root) Eb (major 3rd)
Now look again at the notes of F7:
F (root) A (major 3rd) C (5th) Eb (7th)
You'll see that there is only 1 note that is different :
the C of F7 is replaced by a B in B7♭5
So this helps to explain (I hope !) how the note B on the 4th beat of bar 1 fits in so nicely, with it's fall of a semitone to the Bb of the next bar.

And if we make that 1st chord into F7♭5 (F A Cb Eb), the notes of the 2 chords are identical ( if we think of the Cb as a B ). So the only difference is the note in the bass part - F or B.

Another example of this occurs in bar 13 - last 2 beats - C7♭5 and Gb7♭5 - both chords are the same notes just different root notes.


Just while I'm on this subject (although not specifically blues related), it's also worth noting another pair of chord types that share the same notes but with a different root:
A minor 6 (Am6) = A (root) C (minor 3rd) E (5th) F# (6th)
F# minor 7♭5 (F#m7b5) = F# (root) A (minor3rd) C (flat 5) E (7th)



MBBC18d
[attachment=45612:MBBC18d.pdf]
[attachment=45616:MBBC18d.mp3]

In this example, I've used the "dotted quaver/semi-quaver" method of writing swing parts.

By now, you should have a good grasp of the basic blues sequence and a reasonable understanding of some of the possible substitutions. (There are many more standard subs, far too many to include in this session).

So here is an example of the kind of bass part I might improvise on a typical jazz gig when the bandleader says "Blues in F". I've purposely not put chords on the part. In a real playing situation, you are expected to know the sequence and be able to use your ears to hear the substitutions going on in the piano or guitar and fit in accordingly. This is never an exact science ! Its quite alright to just stick to your own ideas chord wise. It can end up with some interesting dissonances going on which is what makes jazz such an interesting and exciting art form.

Also, bear in mind that in order to make things clear, all the mp3 examples here have a somewhat sterile sound with all the parts being "correct". On a real gig, there would be far more fireworks going on !

The Major

Edited April 2, 2010 by Major-Minor

[billphreets]

invaluable as ever major.. im really into these sessions, i applaud you for the time and effort you make in an effort to educate the basschat community..

cheers

[Major-Minor]

[quote name='billphreets' post='786634' date='Mar 26 2010, 10:08 AM']invaluable as ever major.. im really into these sessions, i applaud you for the time and effort you make in an effort to educate the basschat community..

cheers[/quote]
It is my pleasure, billphreets.

The Major

[spiltmilk_2000]

Hi Major, many thanks for all of your hard work and time in pulling these lessons together.
These chord substitutions are something Im really interested in as I'd love to get involved in playing jazz or at least being able to jazz up my blues playing...

Anyway, apologies if this is a silly question but here goes...

Assuming Im playing with non-jazz-educated guitarists who are playing a straight blues progression. Can i as a bassist use some of the note choices you suggest here or does the whole band need to be playing the same substitutions? Im guessing if i start introducing b5s etc while the band are playing dom7 chords it wont sound too good? Or, if I play those substitutions will it kind of suggest the harmony of the substitutions?

Not sure Ive explained my question very well

Thanks if you can help!

[ZMech]

can i second the previous question. will it start sounding like a mess if i start subbing in chords on bass whilst the others are playing a standard progression?

[Bilbo]

[quote name='Zach' post='1009913' date='Nov 2 2010, 06:55 PM']can i second the previous question. will it start sounding like a mess if i start subbing in chords on bass whilst the others are playing a standard progression?[/quote]

Yes No Maybe - depends on the chord voicings, their note choices, your note choices etc. Recommend you try stuff out in the practice room. If their chord voicings are full of root notes you may clash but, if they are more 'open' voicings, your options are wide open. Learn to hear what's good and what's not.