II-V Chord Progression

Was talking to Brady, my good msn musician pal from Vancouver, Canada~ this morning before i went
to camp in the afternoon. He's a genius lah~ Was teaching me bout II-V chord progressions.
I find dat we both are very similar in the way we approach the teaching of music. Very patient,
very clear, very precise and he brings forth the idea in a very simple way dat's easily understood.

I've learned from him a generous amount of stuff about jazz improvisation, chord formations
and jazz modes etc etc.. Without fail, i'd always save those MSN conversations we have about
music stuff. And he's very ready to share wat he has learned with me. I believe dat's how
we should all learn - dat is to teach others wat we know and in turn reinforce our current
knowledge. You might never know wat you can learn when you teach ppl~ So yeah i'll try to
rephrase wat he's taught me.

Basically, to improvise over a chord, we gotta first look at the chord and figure out what key
it's from. I.e, what key it is diatonic to, and what its relationship to that key is. After
knowing this, you can then figure out wat scale to play over it. Like for example, a chord progression
like this: Dmi7-G7-Cmaj.

When you see a Dominant 7th chord (A7, F#7, Bb7 etc) such as G7 here, it is almost always
functioning as a '5th of' something. This is because the Dominant 7th chords are always build
on the 5th degree of a given major scale. Therefore, G7 is functioning as the 5th chord of the
C major scale. Likewise, the Dmin7 chord here is functioning as a '2nd of' something,
ie. IImin7 of the C major scale. In as such, we can see dat this chord progression is basically
a II-V7-I chord progression, which is by far the most common chord progression you'd find out
there in pop/jazz music.

So, Dmin7 and G7 are chords in the key of C major, i.e they are formed from the scale of C
major. So, in saying dat, you can play the entire scale of C major over these 3 chords and
you'd sound ok.. not fantastic sounding but yeah not wrong sounding at all definitely.
Now since we know Dmin7 is the 2nd degree chord of C major and G7 is the 5th degree chord of C
major, thus we can add more colour to the improvisation by using the Dorian and Mixolydian
modes respectively.

So, you'd play the Dorian mode of C maj scale over the Dmin7 chord and the Mixolydian
mode of C maj scale over the G7 chord~ As simple as can be. Although there arent really any
'wrong' notes in jazz music, BUT there are some notes dat can sound real bad if you played them
with emphasis.. they'd be ok if they were just passing tones though.

The basic rule is this - Any note of a scale that is a half-step above a chord tone is an avoid
note. I.e, in that G mixolydian scale to play over the V chord, the C (which is the 4th note of
the scale) would be an avoid note, because it is a half-step above B, which is the 3rd of the
G7 chord.

However the exception to this rule is when you encounter II chords in the Dorian mode. In this
case, the 6th note of a dorian mode, even though it's a whole-step above the 5th, IS an avoid note.
For example, the chord tones of Dmin7 are D F A C, don't play notes dat are half-step above
these chord tones i.e D# F# A# C# AND dun play note B because it is the 6th note.

Finally, in the chord of Cmaj, the avoid note would be an F because it is half a step up from
E which is the 3rd chord tone. Therefore, beware of playing the 4th note in a MAJOR chord.

Jazz improv or any other improv for dat matter is actually quite easy to understand. The only difficult
part is you gotta know your modes and ur chords and scales very well in order to improvise superbly.
The chord progression is wat gives the melody a direction, an emotional direction. Once understood,
you can then improvise over these chord progressions and spread the icing on the cake~