The 12-bar blues sequence, tritones and shells

Music Lesson: Blues in F by Thelonious Monk

Now, let's turn our attention to the blues, a Blues in F, in fact, by Thelonious Monk.

The Chords of Blues

Before we dive in, let's look at the chords:

• The typical sound of the blues is the dominant seventh chord.
• For a blues in F:
  • The tonic (I chord) will be F7, not F major 7.
  • This applies to the IV chord and the V chord as well; they will all be flattened sevenths.
• Every chord in the blues will be a dominant seventh, which sets the blues apart harmonically from Western music.

"You don't normally get dominant sevenths all over the place."

You could say that "Down the Line" also had a blues tonality because every chord was a dominant seventh.

The 12-Bar Sequence

The 12-bar sequence, in its simplest form, goes as follows:

1. 4 bars on the tonic (F7)
2. 2 bars on the IV chord
3. 2 bars back to the tonic
4. 2 bars on the V chord
5. 2 bars back to the tonic

This sequence is repeated over and over.

Playing the Chords

Now, let's look at how you might play these chords:

• Left Hand Chord Shape:
  • Start with F7 in second inversion.
  • This shape allows you to transition easily to Bb7 in root position with minimal movement, it's right next door.
  • The C7 is also conveniently located nearby.

"You don't probably even need to look once you get used to those changes."

Practice Tips

Take a little bit of time to get used to these shapes and play around with the 12-bar sequence. You can use the Straight No Chaser backing track for practice.

Note: In Straight No Chaser, I've simplified those voicings. In fact, I've left out half the notes.

The Tritone Concept

Let's explore what happens when you leave the root and fifth out.

• By removing F and C (the root and fifth), you are left with Eb and A.
• This combination is called a tritone:
  • You're playing the seventh of the chord on the bottom and the third on top.

"That's actually a really cool way to play an F7 chord, even though you don't have the root."

This tritone creates a "magic interval" when inverted.

• If you play A and Eb, it's still three tones, hence, the name tritone.

Chord Variations

With the Bb7 chord, by leaving out the root and fifth, you get D and Ab (third and seventh). This is right next door to where we were. Instead of moving up a fourth, we've gone down a semitone.

With the C7 chord, leaving out the root and fifth gives you E and Bb, which is a tritone and a semitone above where we were.

"So how cool is that?"

Shell Voicings

After practicing the tritones, remember that these are rootless voicings. Sometimes, you may need to include the root in the chord.

• If you want to add the root, I suggest playing what I call a shell (just the root and seventh of the chord):
  • F7 could be played lower down; however, avoid playing the whole chord down there to prevent muddiness, the shell sounds really nice.
  • Similarly, Bb and C can also be played as shells (root and seventh).

"That, in fact, is more in the style of Thelonious Monk."

This approach reflects Monk's favored style of playing dominant seventh chords, often referred to as Bud Powell voicings, a common practice among bebop musicians of the 40s and 50s.

Final Practice

Take some time to play with these voicings following the chords of Straight No Chaser on the backing track.

Before you attempt the full arrangement, it's worth mentioning that Straight No Chaser includes an extra chord change in bar two, known as a quick change.

• This is a very common variation on the blues sequence.
• We start with the basic sequence and introduce a IV chord in bar two for just one bar.

Otherwise, everything remains the same. Happy practicing!