Ok, so I've been working a lot on my songwriting as of late. I'm getting a lot better at making chord progressions and knowing when to use a major/minor chords, as well staying in key. A lot of my chord progressions are a bit bland so I've been trying to incorporate some extended chords in my playing. What I'm having a hard time with is knowing when to use, say, a 7th chord. For example - If I'm playing a chord progression in the key of G major, which chord would sound "good" with an added 7th? the IV? the V? the iii? What about an added 9th? or 11th? Any advice on this would be much appreciated, and would help me out immensely.
You just figure out if the jazz chord played will fit into the key you are playing in. For key of G (being the I chord) you could use a Cmaj7 (IV) or Am7 (II). Do note that maj7 is not same as dominant 7th. As for 9ths, you could substitute in a D9 (V), since a D9 has notes that fall in G (D9 = D, F#, C, E). Just learn the keys and what sharps or flats are in each key, then you'll be ok 99% of the time.
Just add the 7th from the scale. That would make, in the key of C, Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, Bm-5 (or Bdim). All chords "work" with a 7, you just have to play the right 7 (major or minor), you won't see many standard chords played in jazz. Oftentimes, for example if the melody strays out of key and lands on the b9, you could change the chord for that certain note into a b9 chord.

A tip: I find that learning theory is the most effective when you disregard your guitar, and just focus on the theory in itself. A saying goes: Practicing technique makes you a better guitarist, practicing theory makes you a better musician".
Last edited by Aziraphale at Mar 19, 2009,