Backdoor Dominants in Jazz: Understanding How They Work

If you're a jazz musician, you've probably heard of backdoor dominants. But what exactly are they, and why do they work? In this post, we'll explore this concept and help you understand how backdoor dominants can add depth and complexity to your jazz chord sequences.

So, what are backdoor dominants?

Essentially, they are dominant 7th chords built on the flat 7th of a key, which are used as substitutions for V7 chords. In jazz standards, you'll find them in popular tunes like Lady Bird and Stella By Starlight. It's important to recognize these chords when you see them, as they're a common feature in many jazz chord sequences.

The backdoor dominant is often preceded by a ii chord, which creates a little distraction and sets up a ii-V resolution. However, instead of resolving to the expected I chord, the backdoor dominant resolves somewhere unexpected. This creates a surprise for the listener and adds interest to the chord sequence.

To understand why backdoor dominants work, it's important to know that dominant 7th chords are often altered in jazz. This means that we can add flat 9s, sharp 9s, sharp 11s, and 13s to create a more complex sound. When we take into account the possible alterations on both the V chord and the backdoor dominant, we find that there are many common pitches between the two chords. This makes them interchangeable, and we can substitute one for the other.

To help you visualize this concept, we've created a little sheet that shows the dominant 7th chords and how they function when playing backdoor dominants in the key of C major. You can download this sheet for free or follow along on screen.

Let's take a look at the chords in the key of C major: Fmi7 - Bb7 - Cmaj7

The backdoor dominant in this sequence is Bb7. If we play the sequence normally, we would expect it to resolve to Eb, which is the ii-V-I resolution in the key of Eb. However, with backdoor dominants, we resolve to Cmaj7 instead. This creates a little surprise for the listener, as they're expecting a different resolution.

So, why do backdoor dominants work?

Essentially, it's because the dominant 7th chords are interchangeable. When we take into account the possible alterations on both chords, we find that there are many common pitches between them. This makes them functionally similar and allows us to substitute one for the other.

In conclusion, backdoor dominants are a technique that can add depth and complexity to your jazz chord sequences. By understanding how they work, you can use this technique to create interest and surprise in your music. So, the next time you come across a backdoor dominant (bVII7), remember that it's a substitution for a V7 chord and experiment with different resolutions to create unique and interesting chord progressions.