Last week in our article "Moving Forward; Melodic Progression," we mentioned the different perceptions of the "direction" in music, horizontal and vertical. Recall, music can be melody, it can be chords, and usually a combination of both. We took a close look at the notion of "pull" in the former, but this time we want to look at communicating the harmonic, vertical "guts" of a simple two chord jam.

You could think of these as the first two chords of a 12-bar blues. You could also just take them as they are; maybe you actually sat in a rehearsal waiting for other band members to get their gear plugged in, and someone started wailing on these. It could even be said that major professional careers have been launched on not much more than these two chords.

A7, D7

If we analyze these, we could label them I7 and IV7. In the key of A, they would be based on the first and fourth scale degrees. Notice with the lowered 7th, we have the problematic departure from a major scale (A, B, C#, D, E, F#, G#, A) from G# to G natural, but this is the character of the whole blues genre, that restlessness or defiance, the unsettled esoteric theme of "I'm never happy" communicated in the lyrics, as well. We have the same in the D7 (D, E, F#, G, A, B, C# D), we lower the 7th from C# to C natural.

Two scales you'd use to jam on (don't say "Blues Scale," you advanced theory people; we aren't there yet...) would be:
A7 : A, B, C#, D, E, F#, G, A
D7: D, E, F#, G, A, B, C, D

You'd be fine wandering around these notes (theory buffs call these Mixolydian), but the real harmonic "meat" here is in the 3rd and 7th of each chord, that restless Tritone of C#/G and F#/C. Notice if we invert the second one on the fretboard (C/F#), we have a nice one-fret movement, down:

This is what you want to emphasize when jamming on the chords. No matter what kind of melodic detours you take, you want to feed the beast. When you're playing an A7 and D7 chord, the attention needs to go to them.

What's cool about the mandolin fretboard is how these notes are duplicated with a visually clear geometric pattern. Take these notes all around and you can access this secret treasure intuitively and intentionally.

Okay, you blues experts, add in your harmonic library the lowered 5ths (A7 would be Eb, D7 would be Ab) and minor 3rds (A7 would be C natural, D7 would be F natural) if you want, but the main thing here is grab these tritone notes. You'll really impress your friends!

Whatever you do, don't tell them how easy it is to do this on a mandolin...

Further:
Mandolin Chord Economics
Jazzed Pentatonics
Applying Turnarounds
Another look at Turnarounds
Chord Combinations for the Lizard Ear

Posted by Ted at May 6, 2010 9:41 AM