My new game is trying to insert diminished chords wherever I can under a melody. Level one of the game was A-melody to Fly Me to the Moon like so (chords in bold are original harmony, chords in parentheses are passing):
Am7-Ab diminished-Am7-Edim.-Dm7-Edim.-Dm7-Adim.-G7-G13-Em7-Dm7-CM7-(C#dim.)
FM7-Edim.Dm7-C#dim.-Bm7b5-C#dim.-Dm7-F#dim.-E7-D#dim.-Bm7b5-G#dim.-Am7

I got some ideas from a chord-melody arrangement I downloaded years ago from Guitar College, but quickly found myself improvising my own harmony, which is of course exactly what should happen. The use of diminished chords comes from an video-lesson with Joe Beck called “Jazz Chord Workout.” He demonstrates how to harmonize a harmonic minor scale using this approach, which was a paradigm shift for me since the only approach I knew was diatonic. Jim Hall also demonstrates an approach to harmonizing a mixolydian scale using dominant chords in a video I saw, so I guessed that all of the diminished chords used here would be enharmonic to the dominant b9 of the chord that follows it: Ab diminished=E7b9, E diminished=A7b9, A dim.=D7b9 F# dim.=B7b9. Looking at the roots of these chords, it’s immediately obvious that they are a fourth apart, just like the original harmony.

Chord surplus has never really been a problem for me. I love chords and am always searching for new ones. Digging through some old lessons, I found a bunch of altered voicings with flatted or sharped 5ths. They sounded good, but initially I didn’t know what to do with them! The reason they hadn’t become part of my vocabulary was because they didn’t sound very good on my guitar and were hard to play. That all changed with the GB-10! Unfortunately, applying them is tricky. Usually I play a dominant #5 chord before a minor 9th, but these are more difficult to visualize and finger than the basic”stack,” “stair” or “bucket” shapes I know. After a few hours of shedding last night, I was able to incorporate them into some V7+ -> i cadences, and then of course ii7b5->V7+ -> i progressions. I was able to visualize the new augmented chords by lowering the 5th which yeilds a familar dominant 7 shape. The fingering is completely different though so it’s going to require a bit more work. One really nice side-effect of this is that I gained a deeper understanding of the relationship between these and minor 7 b5 chords, and diminished chords. They follow each other very logically, like a V9 follows a m7. (There’s only a half-step between a diminished chord and a m7b5.) But you could substitute an augmented chord for diminished chord for greater variety — if your fingers are fast enough. This sounds just as naturally, since the augmented scale also has a b5. Like diminished chords, augemented chords can also be displaced from chord they’re resolving using different intervals. For example, I discovered that I can play (build) a chord a minor-third away from the root and it sounds good.

Tricker than the augmented chords are the parallel dominant flat-fives, and the wierd voicings I got from my lessons with Pete Montgomery and Jody Fisher.