7/7/06

Half-step subs/related ii-7s, part two

A few posts ago we looked at a simple ii-V7 substitution that implies a secondary dominant over the ii-7 by playing a minor seventh chord up a half-step from the ii-7. This implies a subV7 of V7 because you are playing the related ii-7 of the subV7 (related ii-7s and V7s are interchangable as far as substitution goes).

original
D-7 /G7 /Cmaj7

played
Eb-7 /G7 /Cmaj7

implied
Ab7(#11)/G7 /Cmaj7

Now let's take this same concept one step further and substitute the related ii-7 of the subV7 of Imaj7 for the regular V7. This sounds convoluted but is so simple to calculate on the fly. All you have to do is play a minor seventh chord a half-step above the dominant.

So over this
D-7 /G7 /Cmaj7

play
Eb-7 /Ab-7 /Cmaj7

implying
Ab7(#11) /Db7(#11)/Cmaj7
subV7 of V/subV7 of I/Cmaj7

Very, very cool. Very, very easy to do.

2 comments:

Larry said...

I can hear the Ab7#11 Db7#11 to CMaj7 better than Ebm7 Abm7 to CMaj7 at this point. But very cool concept for me to play with. Larry

David Valdez said...

While this sub is a outside sounding, it's still totally within the realm of functional harmonic resolution. It helps to outline the chords clearly as you substitute more dissonant subs.

The principle that related ii-7s and V7s can be substituted is one of the primary rules of substitution. It's alright if the substitute chords are very dissonant when played of the existing changes, as long as they have strong harmonic motion and resolution.

It may take a while to get used to the harmonic logic of some substitutions. Some only work at faster tempos. Post-Bop is much more dissonant than classic Bebop, but it is usually still based on functional tonal harmony. The subs that I am talking about here are best used to create lines over existing changes.
Keep working with these until you get used to the internal logic of the substitutions, they are meant to create a high level of dissonance that still has a strong resolution.