Ah, the diabolus in musica: ‘The Devil in Music’ it was called centuries ago. The tritone interval was considered so dissonant that it led to stories of singers in the church being banned from using it. While kinda cool, stories like that are likely not true; in fact, the tritone was used in many Baroque and Classical compositions. Instead of focusing on the notes today, we will focus on the use of the tritone in chords.
Rock guitarists have it easy. They get to just stand there and look cool while playing chords, running around the stage while money rains down on them from above. Well, if you get bored of the same old static chord progressions like I do, it’s time to make rhythm-playing fun again, all while inwardly smiling about the cool harmonic sophistication you display for your bandmates and fans.
This series will focus on rhythmic chords, and the idea of chord substitution. This is the idea that in a given progression, you can substitute one chord for another, cooler/hipper/exotic sounding chord- all while keeping the progression flowing. We will focus on the tritone here, a chord either three whole steps above, or three whole steps below the chord you want a substitute for.
Before We Start…
Western harmony breaks chords in two categories: Chords that have tension, and chords that don’t. Or, we can say, chords that are at rest, and chords that feel like they need to move somewhere.
Take this example, a normal A/E7/A chord progression:
Notice how the A sounds at rest, but when we move to the E7 chord, we want to really come back to that E. This is the standard tension and release aspect of western harmony, and it’s all over classical music, rock, jazz and blues.
We’re going to first focus on that middle chord. That E7 is important because of the tension it holds. When I was first studying guitar I was intrigued by the tension. Why do my ears want to resolve this chord? What’s so special about this chord? Later, I figured it out, but it took some digging.
The musical notes in an E7 are E G# B D…a common way to play this is like this:
Actually, the entire chord isn’t tense, and in fact, we can break it down into two notes that hold all of the tension here: G# & D.
These two notes are what we call a tritone away from each other. A tritone is an interval of three whole steps, and a whole step is two frets apart. This interval is also called a diminished fifth. Most guitarists who have played any Black Sabbath or Metallica song have probably played this interval. It’s like a power chord, but your third finger moves down in pitch one fret, creating this evil, tension-filled sound that much of modern metal was built on. Here is a power chord, and then the tritone after it.
OK, back to our E7 chord. The cool thing is that tension-filled tritone in the E7 chord also exists in another 7th chord!
Now, look at the notes in the A#7 in the tab:
Notice anything? The circled notes are the same tension-filled notes that give the E7 its distinctive sound! And how did I pick such a random chord as A#7? Well, it is a tritone away from E!
So, we now learn that for any dominant 7th chord, we can substitute another dominant 7th chord a tritone away.
So if the progression goes A/D/A/E7/A:
I can take that E7, and substitute an A#7, which is a tritone away from the E. It is also ½ step (one fret) higher than the tonic chord, A.
So, if your progression is made up of only dominant chords:
Then any one can be changed out for another dominant 7th chord 3 whole steps away. So a kinda boring progression like the one above can have every chord switched out whenever you want.
So, A7 can become D#7, and D7 can become G#7, and we already know E7 can become A#7. I don’t have to switch these out every time, either. Here is the same progression as above but with added tritone substitutions. The cool thing is that it always works harmonically in a song, although it sounds a little strange at first. Play the progression a few times, and try to pick out individual notes in the chord. Listen to how these voices in the chord lead your ear to the next chord. I’m holding each chord two beats, but you can experiment with many types of rhythms and substitutions.
Piano players are wonderful at this, which is why their idea of harmony is way beyond most guitarists. But we don’t have to hang out in the cave forever. Time for us to get in on the sweet, sweet harmonic action.
See, you don’t have to be bored playing rhythm chords behind a soloist. You can have just as much fun, coming up with sophisticated substitutions and providing a changing harmony instead of boring, static chord progressions. Thing is, good soloists love this, and it is the basis of ‘comping chords’ in jazz.
A note about tone: Complex chords and harmonic playing benefit for a tone more on the clean side of things. My tone isn’t squeaky clean, but if I pile on the gain, the overtones and harmonics generated by the distortion smear the harmony. Ever play an open C chord with a ton of distortion? Yeah, kinda like that.
This is a great video explaining the concept further:
How do you make your rhythm playing stand out? And who is your favorite rhythm guitarist?