As I've mentioned in my previous post, I read the new book by Mick Goodrick and Tim Miller: Creative Chordal Harmony for Guitar. In this book the authors introduce their concept of Generic Modality Compression (GMC). Since this term is not really self-explanatory (at least not for me), I was curious what it is all about.
There are actually only about 10 pages to read, the remaining pages (about 80) are examples in standard notation (no tabs). So, I've read everything, actually twice to make sure I didn't miss anything, I've looked at all the examples, and I've played through many of them. Let me first summarize what I think this book is about, and what you can find in those 90+ pages.
The basic concept is very simple and can be explained very easily. Take a heptatonic (7-note) scale and remove the root ("compression"). Now you're left with six notes. Divide these six notes into two groups of three. If you try (or if you know basic combinatorics), you'll see that there are 10 possible ways to do that. Now you have 10 pairs of three notes. Each pair, when combined, gives you all six notes of the "compressed" scale (i.e., all notes except the root). These 10 pairs of three notes can be played as three-part chords, or they can be played linearly as melodies (in any permutation, of course). That's what Generic Modality Compression is about.
So, what can you do with it? The idea is that instead of playing complete four-part or five-part-chords, you choose a chord-scale for the chord you want to play, apply the process described above, and then you play the above mentioned three-part chords (either harmonically or melodically). This will hopefully lead you to new voicings and will open up new sounds that you might not have discovered otherwise.
Let me give you an example to show you how it works in practice. If G7 is the chord over which you want to play, first choose an appropriate scale, e.g. G-mixolydian: g-a-b-c-d-e-f. If we remove the root we're left with six notes: a-b-c-d-e-f. Now we get the following 10 three-note pairs:
a-b-c * d-e-f
a-b-d * c-e-f
a-b-e * c-d-f
a-b-f * c-d-e
a-c-d * b-e-f
a-c-e * b-d-f
a-c-f * b-d-e
b-c-d * a-e-f
b-c-e * a-d-f
b-c-f * a-d-e
Each pair contains all six notes, i.e. each pair completely represents the scale apart from the root note G. You can play each of the above groups of 3 pitches as three-part chords. Note that you can use inversions and open voicings, i.e. the three-part chord a-d-f (second inversion of a D minor triad) can (and should) also be played as (from low to high)
In this way you'll get tons of three-part chords (and six voicings for each chord) to create new and unexpected sounds (and to keep you busy for a while).
Those 80 pages of the book in standard notation just contain all possible pairs of three-part chords and their inversions (close and open voicings), first for the mode C ionian (C major). After that the principle is applied to the jazz standard Stella By Starlight. For each chord in that tune, a chord scale is chosen, and the corresponding 3-part-chords are listed. You can listen to the examples on the CD, and there are also play-along tracks for you to practice. Later in the book, there are also examples for the melodic use of this concept ("Arpeggio Permuations"). This is very simple, just take the 3-part-chords from the previous pages and arrange the notes linearly, i.e. play them one after the other.
OK, that's what this book is about and what you can expect to find in it. Now I would like to make a few critical remarks. First of all, the whole GMC concept as introduced in the book is based on reducing a 7-note scale to a 6-note scale by removing the root. The motivation for removing the root appears to be the 'fact' that the root is played by the bass player, so the guitarist shouldn't bother to play it. Well, especially in a jazz context, you won't find a bass player just playing the root. Maybe the bass will play the root on the first beat of the bar (or maybe not), but anything can happen after that. If also the accompanying instruments are to be given some freedom - as is normally the case in improvised music - then all instruments are responsible for establishing the sound of the mode/chord at any given time. For this reason I think the motivation for removing the root from any 7-note scale is a bit weak. There are great sounding chords/voicings including the root (in a high register), so why not use them?
I feel that there's another problem with GMC: there is no mention of how to treat avoid notes. Avoid notes are notes in a scale which are not (traditionally) available as tensions for the related chord. E.g., if we choose C ionian (C major) as a chord scale for a Cmaj7 chord, the note F is considered an avoid note, i.e. a note which cannot be added as a tensions to the Cmaj7 chord. Consequently, if a Cmaj7 chord should be outlined using GMC, all 3-part-chords containing the note F should be avoided. But this is not done and not even mentioned in the book. Instead, all 3-part-chords containing a C are avoided, yet this is not always necessary, depending on the chord voicings played by the other instruments.
I understand that GMC restricts itself to three-part chords, but this fact is not discussed in the book. I think that 4-part chords do sound great on the guitar, and just because six notes (i.e., the compressed scale) can so beautifully be split in two groups of three notes should be no reason to leave out great sounding 4-part voicings.
Finally, while browsing through the book I got the feeling that there are too many redundant examples. E.g., all the permutations of melodic possibilities of three-part chords. I think it is obvious how to take apart a three-part chord and play its three notes linearly, in any desired sequence. The authors spend many pages on writing out all those possibilities. I would have preferred a few more pages of discussion and motivation, e.g. addressing the issues I've mentioned above (avoid notes, etc.).
On the bright side, the accompanying CD sounds great and inspires you to play through some of the examples yourself. While doing so, you will definitely discover some chord voicings which you haven't played before. What I also found inspiring was that the book showed me one more possibility to learn a tune: by figuring out all possible (three-part) voicings of the appropriate chord scales for the chord progression of the tune. This is quite some work, but it will give you a lot of freedom while playing through the changes, either harmonically or melodically. And finally, I found the book a great reading exercise. Since there are no tabs you have to read everything from standard notation. And since many of the chords are no standard triads, (sight) reading them can be quite challenging. So despite having a few critical remarks on the book's concept and its presentation, I got quite some inspiration out of it, and I discovered yet another way to study a tune.
Here a short summary:
- nice CD, some great and surprising sounds
- shows you a very thorough method to study a tune
- good reading exercise
- no mention of avoid notes
- completely disregarding the root is not sufficiently motivated
- too many pages of redundant examples, at the expense of room for discussing and motivating the concept more thoroughly
- artificial restriction to three-part chords
Also check my post on II-V-I progressions using GMC.