Tritones
It is not always necessary to play a whole chord to get the effect of a chord. It often works well to take only the most essential notes of the chord and leave the other notes to the bass player and whoever is playing the melody. Here is a C7 chord. Its notes are C E G Bb. The second diagram here is the Tritone within the chord. Listen to the effect it produces.
c7
The root note (C) can be left to the bass player. The 5th (G) is not an essential note, so it can also be left out. It is the 3rd (E) and the flattened 7th (Bb) which are essential to the sound of the dominant 7th chord. These are the notes which form the tritone. The tritone is so named because the two notes are exactly three whole tones apart. The tritone interval is exactly half an octave, which means if you invert it (turn it upside down), the two notes are still three whole tones apart. This means the tritone will work regardless of which note is on the top, making it possible to find tritones in many places on the fretboard. Here is an example of the way tritones may be used. As you can hear, it’s a great sound.
Here are two examples showing the patterns formed by tritones across the fretboard. Memorize the patterns and learn them in all keys.
