Exploring Half-Diminished & Fully Diminished Chords

Welcome to this in-depth lesson on half-diminished and fully diminished chords. These two chord types are essential in jazz harmony, particularly in minor key 2-5-1 progressions and chromatic voice leading. By the end of this lesson, you will have a deep understanding of how to voice, practice, and creatively apply these chords in your playing.

Understanding Half-Diminished Chords (Minor 7♭5)

The half-diminished chord, also known as a minor 7♭5 (e.g., B-7♭5), is a common sound in jazz progressions. It is often found as the 2-chord in a minor 2-5-1 progression, leading to a dominant chord (5) and resolving to the tonic (1).

For example, in A minor, a 2-5-1 progression would be:
B-7♭5 → E7♭9 → A-7

Constructing the Half-Diminished Chord

A half-diminished chord consists of:

• Root
• Minor 3rd
• Diminished 5th (♭5)
• Minor 7th

An easy way to visualize this chord is by thinking of it as a minor chord with a lowered 5th or as a minor 7th chord built from the Locrian mode (1, 2, ♭3, 4, ♭5, ♭6, ♭7).

Practicing Half-Diminished Chord Voicings

1. Simple Inversions

One of the simplest ways to practice half-diminished chords is to think of them as a major triad with a different bass note. For example, B-7♭5 shares the same notes as a D minor triad (D-F-A) with B as the root.

2. Chromatic Exercises

Practicing half-diminished chords chromatically across the keyboard will help solidify the shapes under your fingers:

Play:
B-7♭5 → C-7♭5 → C#-7♭5 → D-7♭5, etc.

3. Expanding the Chord with Extensions

Adding a natural 9th (C# in the key of B-7♭5) creates a more open sound. Experiment with different placements of the 9th in your voicings to find what works best in a musical context.

4. Rhythmic Variations

Rather than playing chords statically, practice applying different rhythmic patterns to make them more dynamic and usable in a comping or soloing setting.

The Fully Diminished 7th Chord

The fully diminished 7th chord is different from the half-diminished chord in that it consists entirely of minor 3rd intervals, making it a symmetrical structure.

How to Build a Fully Diminished 7th Chord

For example, B diminished 7 (B°7) consists of:

• B (root)
• D (minor 3rd)
• F (diminished 5th)
• Ab (diminished 7th)

Because the notes are equidistant, you can move any diminished chord up or down by a minor 3rd and still retain the same chord shape.

Common Uses of Fully Diminished Chords

• As a passing chord between dominant chords (e.g., Cmaj7 → C#°7 → D-7)
• As a substitute for a dominant 7♭9 chord (e.g., B°7 can replace G7♭9)
• In blues progressions as a chromatic movement between the 4 and 5 chords

Applying These Concepts in Jazz Harmony

One of the most powerful applications of diminished chords is their ability to resolve smoothly through chromatic motion. For example, in a jazz setting:

1. Descending Half-Diminished Movement
   Try moving from B-7♭5 to A#°7 to A-7, creating a smooth chromatic descent.
2. Ascending Fully Diminished Movement
   A diminished chord can move upwards by minor 3rds, allowing for smooth modulation:
   B°7 → D°7 → F°7 → Ab°7
3. Substituting Dominant Chords with Fully Diminished Chords
   Instead of G7 in a 2-5-1, try replacing it with B°7 (shares many of the same tones).

Practice Tips

Visualize the Relationship Between Chords

• Think of a half-diminished chord as a minor triad with a different bass.
• Think of a fully diminished chord as a dominant 7♭9 substitute.

Use Chord Inversions to Smooth Voice Leading

• Experiment with different inversions to connect half-diminished chords fluidly within a progression.

Move Diminished Chords in Minor 3rd Intervals

• Fully diminished chords can be transposed up or down by minor 3rds while keeping the same structure.

Apply Rhythmic Patterns When Practicing

• Don’t just play chords statically; use different comping patterns and rhythmic placements.

Listen to Jazz Standards That Use These Chords

• Songs like "Stella By Starlight", "Misty", and "Body and Soul" showcase beautiful applications of diminished harmony.

Final Thoughts

By understanding the function, construction, and movement of half-diminished and fully diminished chords, you open up a vast world of harmonic possibilities. Whether you’re comping, soloing, or arranging, these chords provide essential tools for rich jazz harmony and expressive playing.

Happy practicing! 🎶