Theory; Beyond the Sound

Comment by Dave Warner on November 27, 2008 at 6:13am

How about a discussion of some common chord substitutions? I had a class with Jeff Jenkins that covered some of this to a degree. One thing he covered that I didn't catch was the idea of a "tri-tone" substitution. I understand (I think) what a tri-tone chord is, but I don't know how that helps you figure out what chord to sub when.

Comment by Dave Warner on November 27, 2008 at 8:00am

Thanks, Michael. So the dominant seventh chord of which the root note is the tritone, is generally only used as a sub for the V chord? Hm, there must be a better way to say that.

A V-I movement is generally when the tritone sub is used? You wouldn't use a tritone sub for the IV, or the ii, etc...?

Comment by Michael Gurzi on November 27, 2008 at 4:09pm

I think the concept is that you can use the tritone as a movement to a target chord. If you had a situation where enroute to the ii chord, say Dm7 and it was preceded by an A7 (which would be functioning as a 5 of 2 in C) then if you wanted you could use a Eb7 as the tritone sub for A7. It really depends on the sound you want, and how it fits, but you could. Therefore it is not limited to just the V-I movement, but to any chord where a V of something is being played.

In that situation we call any V chord that is not the actual keys V (like G7 in the key of C) then it is called a secondary dominant. So in the above, the A7 to Dm7 in the key of C is a secondary dominant. If you used Eb7, it would be a tritone sub to the secondary dominant.

Crazy stuff

Mike

Comment by Tim McGaughy on November 29, 2008 at 6:25am

One revelation in chord substitutions for me was to realize that the realtive minor was simply an inversion of the Major 6th chord. For example C6 and Ami7 have the notes in them, just different roots actually contexts that determine how they funcion. C6 = CEGA Am7= ACEG same notes in each chord.

Comment by Tim McGaughy on November 29, 2008 at 6:32am

Another sub that I learned by experience was backing up fiddlers. In fact the year that I played backup for Dave at Winfield I also played for a fiddler that was playing some waltz like Gardinia or Westphalia. Any way early in the chord sequence I would have played a D7 and a wonderful backup player from WA state showed me to sub in Am (xx7555) and walk the bass down (7, 6, 5, 4). The Am is functioning like a D9th chord without the bass - D-F#-A-C-E. This makes for some very interesting movement while still maintaining the V7 tension for several measures.

Comment by Michael Gurzi on November 29, 2008 at 10:00am

Great points Tim. One thing for all to note, is that if you learn all of your min7 chords and their inversions, you are also learning the relative Maj6 chords and their inversions. There are 4 inversions of each on each 3 string sets: String set 4,3,2,1; 5,4,3,2; 6,5,4,3 - thats 12 chord forms, but since they can function as or sub for each other, thats 24 chords!!

Also, on your Am7 sub for the D7, yes it sounds like a D9, but the bigger idea is that you can always put a minor ii chord in front of a V. This gives you much more harmonic interest. You can always use that walk down too. great stuff. Thanks Tim!!

Comment by Tim McGaughy on December 17, 2008 at 10:35am

I have three key shapes I use for closed minor 7th chords. For example Dm7 x5x565 Dm7 x5443x and Am7 5x555x (these of course are moveable shapes) Anyone else have other chord shapes that you consistently use? Usually if I'm on a min7 chord I will alternate it with the min6 form to keep the changes happening.

Comment by Mike Bunting on January 22, 2009 at 12:48pm

Good stuff, I love messing with those tritone subs.

Comment by Tim Pulley on January 23, 2009 at 7:11am

Hello all,
I can tell that I will enjoy this group.
Michael, I read your post of Jan 12, boy you hit the nail on the head with that one. I am guilty as charged, I have been working on approaching songs from different angles, but I think that sometimes at jams, either my body or more likely my mind will get lazy, I guess the path of least resistence. I work on the songs up and down the neck, across and in combinations, but get me to a jam it feels like stay with what you know. Thanks for the post, it will serve as a reminder to me to use different positions.
Also, since this is Theory, I would like to learn more about the different modes. I am not much of a theorist, but would love to learn more and more.

Comment by Chad Fette on January 24, 2009 at 5:15am

Mike,
I love this discussion group. I have a question that I think will be easy to answer. How do I figure out the chords in a minor key? For instance, how do I convert D major to D minor?
Thanks,
Chad

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