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The Minimalist Blues - A look at tritones

Guitar Lesson by Kirk Lorange

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The almighty tritone


What's the least number of tones — per chord — required to express a jazz/blues progression?

Two!

That's right, just two, and not only that, the root isn't one of them. The only notes required are the 3 and the flat 7. Remember that in the blues/jazz genre, most, if not all the chords are dominant chords, meaning they all include the flat 7.

Here's the interesting thing about those two tones: they are separated by an interval of 6 semitones, or 3 whole tones. That interval is known as a 'tritone' ... 'three tones'. We know that an octave is 12 semitones, so here we have an interval of exactly half an octave. So if one of those tones is the 3, the other is a flat 7 ... in either direction! This means that every tritone can apply to two different 7th chords, with the roles of each note reversed.

Confused? Let's look at a case in point. Below is a graphic showing two chords, D7 and G#7. Notice how both share the same tritone, the red notes.

animation
The only reason this can be is that in the D7 the 3 is the bottomĀ note and the b7 is the top note; in the G#7, it's the other way around, the b7 is the bottom note and the 3 is the top note. When you hear the term 'tritone substitution', this is what it's all about. Jazz players will often substitute one for the other. Every 7th chord has a 'partner', another 7th chord that uses the same tritone, and the roots of the two chords are a tritone apart. I'll do a lesson on that one day. Meanwhile, let's look at an animation of the five 7th chords in this piece.

g7
Notice how that tritone occupies the same two strings and moves left and right, embedded in each chord in these positions. In the G, E and A, the b7 is the bottom note, the 3 is the top note. In the C and D, it's the opposite, 3 on the bottom and b7 on the top. These tritones are found on all adjacent strings and can become very powerful visual tools for navigating the fretboard and very easy to see down there if you know the PlaneTalk mindset.

OK, back to this lesson. You'll see and hear that I don't play any roots under any of the chords until bar 12, and yet it's very clear to the ear what the progression is. That's because I keep playing those tritones, which I've boxed in green in the video. Once the progression gets going, the context of all of the tritones together quickly tell you what the piece is all about: a fairly standard blues/jazz progression in the key of G. No bass notes, no roots, are required. Cool, huh?

A quick note about the progression: the I-IV-V chords are there -- the G7, C7 and D7. They are the core of any blues piece. The E7 and A7 are what I call 'majorized minors'. In the key of G, the usual E and A chords are minor, but here I've turned them into dominant chords which use the major 3. There is a proper term for this but I forget what it is.

I thought I'd throw some melodic lines to get your left hand limbered up a bit. As you well know by now, I don't think scales, I think chord tones. The line over the C7 chord, which should really read C9, is almost pure chord tones; the line of the G7 is almost pure chord tones (I move through the flat 3 a couple of times). I treated the A7 as a A13, meaning a very extended 7th chord. The line uses most notes from a A Mixolydian mode plus some chromatic 'in between' notes. BUT, and this a big but, I wasn't thinking 'mode'. I was thinking A13. It would be good practice to learn these lines and work on playing them smoothly and with feel.

The take-away from this lesson is that tracking tritones can became a very powerful way of creating lines — improvising — in the blues/jazz world. Most jazz players will tell you that, if nothing else, know where the 3 and flat 7 are for whatever chord you're working through. Why? Because they are the core of a 7th chord, and as this lesson proves, they are all that is really needed. You could play a compact rhythm part just using tritones and be right on the money. If your melodic lines keep using the 3 and flat 7, they will sound nicely 'glued' to the progression.

I will think about a lesson on tritone substition soon, so keep all this in mind.

Until next lesson!



For a mere $4.95, you can download the Guitar Pro file and a printable PDF of the tab/notation of this lesson. The fee helps me to pay for the hosting and running of this site and allows me to create more of these lessons. Click here to order it. Thanks!