In the early eighties I came across an album on Windham Hill by an acoustic guitarist named Alex DeGrassi called "Slow Circle". I was initially drawn to the record because it was all solo acoustic guitar in altered tunings. I thought it would be really weird-sounding so I bought it. To my surprise the music was some of the most beautiful, "inside" guitar playing I had ever heard. I immediately began to experiment with the tunings listed on the back of the album jacket. After about three years I decided that the altered tuning approach was not good (for me) because it negated the years of study and work I had done to understand the instrument and master the neck. Change the tuning and I'd have to start over! So I decided to analyze what it was about these tunings that made them sound the way they did and then figure out how to get the same types of sounds in standard tuning. I came up with three characteristics that produced what I was looking for.
One or two drone notes occurring on top of the progression, usually open strings.
Close intervals (2nds or minor 2nds) in the middle of the chord. When played alone these intervals are very dissonant but when placed in the context of the chord they become beautiful. Many times the dissonant interval is an inverted 9th.
Liberal use of inversions to create smooth bass lines. The bass line often "walks" like in jazz.
The next few pages are what I came up with in the following three or four years. The information is organized in chronological order, that is, the order in which I "discovered" it. It generally goes from simple to complex in technical difficulty but not in harmonic content. Because of the "guitaristic" nature of this material the easy chords to play can sometimes be very complex chords harmonically. I have gotten a lot of mileage out of these chords both in terms of my own writing and in their application to every other style of music I play. There are even a couple of chords I have not heard anyone else play!
One of the things I do when I'm in the middle of a "big picture" type of undertaking like this is to write a song whenever I come across a chord voicing or progression that seems to me at the time to be a major concept. This makes the concept immediately applicable and also helps me to remember it. That is why some of the progressions you'll be getting are actually pieces of songs I wrote along the way.
I've tried to come up with a better way to organize this material over the years that makes more sense from a theory point of view but have not been successful. As is many times the case, the "guitaristic" way is not always the most logical from an intellectual viewpoint but makes sense if you understand the mechanics of the instrument.
These are easy forms physically but can create some complex chords
These chord forms pre-suppose the student has gone through the Vertical Truth series through at least Unit 6.