Diminished Seventh Chords For Guitar (Dim7) - Drop 2 and Drop 3 Voicings

Diminished seventh chords (dim7) are four-note chords widely used in jazz to create tension, connect chords, and add harmonic color. On the guitar, their symmetrical structure makes them particularly useful for chord substitutions, inversions, and movable voicings.

In this lesson, you will learn how diminished seventh chords are constructed, how to play them on guitar, and how to use them in jazz harmony. You will explore chord shapes, inversions, drop 2 and drop 3 voicings, the relationship between diminished and half-diminished chords, and the Barry Harris approach to diminished harmony.

Whether you are a beginner exploring jazz chords or an experienced guitarist looking to expand your harmonic vocabulary, this guide will help you understand and apply diminished seventh chords in your playing.

Diminished Seventh Chord Construction

Diminished seventh chords (dim7) consist of a root (1), a minor third (♭3), a diminished fifth (♭5), and a diminished seventh (♭♭7).

They can be viewed as diminished triads (1–♭3–♭5) with an added diminished seventh (♭♭7).

In other words, they are built by stacking four minor thirds (three semitones) on top of one another.

Symmetry

Diminished seventh chords are symmetrical because the octave is divided equally into four minor thirds.

This means that a diminished seventh chord has four possible root notes, each separated by a minor third.

For example, C diminished seventh (C°7) consists of four notes: C, E♭, G♭, and A. Each note is separated from the next by three semitones (a minor third).

Because of this symmetrical structure, C°7 can also be named E♭°7, G♭°7, or A°7. These four chord names refer to the same set of pitches, with a different note serving as the root.

Comparison With Half-diminished Chords

Diminished seventh chords (dim7) can be confused with half-diminished seventh chords (m7♭5).

The main difference is that half-diminished seventh chords contain a minor seventh (♭7), whereas fully diminished seventh chords contain a diminished seventh (♭♭7).

Comparison With Dominant 7 Chords

Keep in mind the following concept, as it can be very useful for guitar comping and chord melody arrangements.

If you lower any note of a diminished seventh chord by a semitone, you get a dominant seventh chord.

Here are some examples showing the possible connections between drop 2 chord voicings.

These examples are based on the same drop 2 diminished seventh chord shape, with the notes voiced in the order R (root), diminished fifth (♭5), diminished seventh (♭♭7), and minor third (♭3).

By lowering each note of this chord shape by a semitone, you obtain four different drop 2 dominant seventh chord voicings.

Barry Harris Concept

Barry Harris taught that the fully diminished seventh chord lies at the heart of his harmonic system.

By making small chromatic adjustments to its notes, this chord can transform into dominant seventh, minor 6, or major 6 harmonies.

✔︎ Lower one note of a diminished seventh chord by a semitone to create a dominant seventh chord, as explained above.

✔︎ Raise one note by a semitone to create a minor 6 chord.

✔︎ Lower two adjacent notes by a semitone to create a major 6 chord.

✔︎ Raise or lower two non-adjacent notes by a semitone to create a dominant 7♭5 chord.

From this perspective, dominant seventh, minor 6, and major 6 chords are closely connected through chromatic movement around the diminished seventh chord.

Explore the full lesson to learn more about how to transform diminished seventh chords using the Barry Harris system for guitar.

Chord Substitutions

Diminished seventh chords are often used as substitutes for dominant seventh flat ninth chords (7♭9). This technique is known as diminished chord substitution.

Example: A II–V–I progression in C major

Dm7 | G7 | Cmaj7

can become:

Dm7 | Bdim7 | Cmaj7

Thanks to the symmetrical structure of diminished seventh chords, three other substitutions are possible:

Dm7 | Ddim7 | Cmaj7

Dm7 | Fdim7 | Cmaj7

Dm7 | A♭dim7 | Cmaj7

You can also experiment with replacing dominant seventh chords in a common I–VI–II–V turnaround.

Example: A turnaround in C major

Cmaj7 | A7 | Dm7 | G7

can become:

Cmaj7 | D♭dim7 | Dm7 | Bdim7

Explore four ways to use diminished seventh chords to discover more possibilities for jazz guitar.

Drop 2 Diminished 7th Chords

What Are Drop 2 Chords?

Drop 2 chords are among the most commonly used chord voicings in jazz guitar.

They are built by taking a four-note closed-position chord and dropping its second-highest note down an octave.

The formula for a closed-position diminished seventh chord is R–♭3–♭5–♭♭7. This gives the following drop 2 voicing formula: ♭5–R–♭3–♭♭7.

What Is an Inverted Voicing?

An inverted chord voicing is one in which the root is not the lowest note.

As you can see in the guitar diagrams above, the third, fifth, or seventh can be in the bass.

The chart below shows four drop 2 diminished seventh chord voicings: one root-position voicing and three inversions.

In the root-position voicing, the root (R) is in the bass. In the three inversions, the ♭3, ♭5, and ♭♭7, respectively, are in the bass.

This is the principle of chord inversion: the same chord tones are arranged in a different order, changing the bass note while preserving the chord's identity.

Drop 2 Diminished 7 Chord Shapes

That's what drop 2 diminished 7 voicings look like on the whole guitar neck. Each voicing is represented by a different color. 

• Black shape = Root position
• Blues shape = First inversion
• Pink shape = Second inversion
• Green shape = Third inversion

Drop 3 Diminished 7th Chords

What's a Drop 3 Voicing?

Now that drop 2 diminished seventh voicings are no longer a secret, let's explore four drop 3 diminished seventh voicings and their eight related shapes for guitar.

You may be wondering what the difference is between drop 2 and drop 3 voicings.

As explained above, drop 2 voicings are created by taking the second-highest note of a four-note closed-position chord and dropping it down an octave.

The same principle applies to drop 3 voicings, except that the third-highest note is dropped down an octave. This produces four distinct voicings for the chord.

Drop 3 Chord Rules

The lowest notes are always played on the fifth or sixth string, as there are no drop 3 chord shapes with the bass note on the fourth string.

Each voicing includes a string skip.

What Scales to Play Over A Diminished 7 Chord?

There are three main scales to play over dim7 chords.

1 - The Whole-Half Diminished Scale

The whole-half diminished scale is an eight-note scale that alternates whole steps and half steps. It is a symmetrical scale.

2 - The Half-Whole Diminished Scale 

The half-whole diminished scale is also an eight-note scale, consisting of an alternating pattern of half steps and whole steps.

It is a symmetrical scale and the reverse of the previously discussed whole-half diminished scale.

3 - Super Locrian bb7 Scale

The Super Locrian ♭♭7 scale is the seventh mode of the harmonic minor scale.