A diminished seventh chord (also known as a full diminished seventh chord) is composed using a root/1^st, minor 3^rd, diminished 5^th and diminished 7^th (or R/1-3-5-7) intervals played simultaneously. Generally written as C⁷, Cdim⁷ or Cmi⁶⁽⁵⁾, it is good practice to simply use an uppercase C, a superscripted lowercase and the number ⁷ to represent it in writing (ie: C⁷).

A diminished seventh chord occurs naturally in a harmonized harmonic minor scale on the seventh scale degree, and although it does not occur naturally in a harmonized major scale, it does appear in a major scales parallel harmonic minor. The double flat () 7^th is enharmonically equivalent to a major 6^th and is one half-step/semi-tone lower than a minor 7^th interval, hence the name diminished 7^th.

The tonality of a diminished seventh chord is dissonant and distinctly unresolved, it "drives" towards root resolution as opposed to a major seventh chord which is stable and centered.

Diminished Seventh Tetrad

In music theory, a diminished seventh chord belongs to a group of chords called tetrads. Generally, a tetrad is a four note chord composed using specific intervals, those being the root/1^st, the 3^rd, the 5^th and the 7^th degrees (note absence of interval quality). As previously shown, a diminished seventh tetrad is composed using a root/1^st, minor 3^rd, diminished 5^th and diminished 7^th (R/1-3-5-7) intervals. Other tetrads are built by raising or lowering the 3^rd, 5^th and/or 7^th degrees. For instance, a minor seventh tetrad interval structure is root/1^st, minor 3^rd, perfect 5^th and minor 7^th (R/1-3-5-7). The interval structure for a minor seventh flat five tetrad is root/1^st, minor 3^rd, diminished 5^th and minor 7^th (R/1-3-5-7), and a major seventh tetrad is root/1^st, major 3^rd, perfect 5^th and major 7^th (R/1-3-5-7).

Major seventh, minor seventh, dominant seventh and minor seventh flat five tetrads occur naturally in the harmonized major scale (tetrads).

Diminished Seventh Chord Profile

Intervals	root/1st, minor 3rd, diminished 5th, diminished 7th or R/1-3-5-7
Stability	Dissonant / Unstable / Unresolved
Grouping Class	Tetrad
Common Names (examples in C)	C7, Cdim7, CDIM7, Cmi6(5)

Diminished Seventh Chord Voicings

The chord voicings below are not shown in any particular key, they are shapes which can be moved around the guitar neck freely using the root note (circled dot) as your navigator. See example below.

• How to use
• As an example, let's say you require a D major chord
• After playing all the chord voicings, you decide on voicing #2
• Voicing #2 has it's root on the 5^th string so you need to find the D note on this string
• Click the notes on the neck chart tab and find the D note on the 5^th fret (5^th string)
• Now play D major using voicing #2 on the 5^th fret
• Use the Octave chart tab to help you remember which notes are where
• Use the Chord chart help tab if your a beginner at reading chord boxes

Diminished Seventh Chord Audio Sample(s)

To download audio sample(s) for later listening, right click on the MP3 link, then from the context menu that appears select Save Target As (Internet Explorer) or Save Link As (Firefox).

Audio Sample Name	Flash	MP3
C Diminished Seventh Chord voicing #2		c-diminished-seventh-chord-voicing-2.mp3

Related Lessons & Resources

• Guitar Lessons
• • How to read chord diagrams
  • Open chords part 1
• Music Theory
• • Harmonizing a major scale (triads)

External Resources

• Diminished seventh chord at Wikipedia.org