Chord TheoryA Diminished 7th chord is a dissonant or unstable chord and generally needs resolution. Guitarists often play the diminished 7 or dim7 (4-note chord) instead of the diminished triad (dim) or 3 note chord.
- dim7 chords are 4 note chords consisting of 3 minor 3rds above the root or tonic, therefore having a root, a minor 3rd, a diminished 5th and a diminished 7th.
- The chord formula for a dim7 is 1 - ♭3 - ♭5 - ♭♭7(6)
- The symbols for a diminished 7th chord are, dim7 or º7
- The featured song for this session using dim7 chords is 'Love is a Losing Game' written and performed by Amy Winehouse... some excellent backing by the guitarist and bass player.
- For Country Music Fans we have another featured song by Patsy Cline called Crazy. It has a great melody with some very nice diminished 7 chords and a vast array of barre chords. Every learning guitarist will enjoy playing this one.
Example: Calculating C diminished 7th... Cdim7 or Cº7
- Diminished 7th chords consist of the 1st, ♭ 3rd, ♭5th and ♭♭7th notes of a Major Scale
- Remember that a minor third is equal to 3 half steps or 3 semitones. If we move a minor third upwards from C, we get E♭...(C - C# - D - E♭). If we move another minor 3rd upwards from E♭, we get G♭... (E♭- E - F - G♭). If we move another minor 3rd upwards from G♭, we get B♭♭... (G♭ - G - A♭ - B♭♭)... B♭♭ is actually an A. We call it a B♭♭ because it is the 7th note of the C diatonic scale which is B.
- Remember that all chords are based around the major scale of that chord, therefore C chords are built from the C major scale which consists of no sharps or flats. The scale reads as follows: C - D - E - F - G - A - B - C
- Formula for a dim7 chord = 1 - ♭3 - ♭5 - ♭♭7
- Substitute the notes into the formula: 1=C, ♭3=E♭, ♭5=G♭, ♭♭7=♭♭B(A)
- Cdim7 reads as follows: C - ♭ E - ♭G - B♭♭(A)
|♭5th||E♭||E||F♭ (E)||F||G♭||G||A♭♭ (G)||A♭|
|♭♭7th||G♭||G||A♭♭ (G)||A♭||B♭♭ (A)||B♭||C♭♭ (B♭)||C♭ (B)|
|♭3rd||F#||G♭||G||A♭||A||B♭♭ (A)||B♭||B||C♭ (B)|
|♭5th||A||B♭♭ (A)||B♭||C♭ (B)||C||D♭♭ (C)||D♭||D||E♭♭ (D)|
|♭♭7th||C||D♭♭ (C)||D♭||E♭♭ (D♭)||E♭||F♭♭ (E♭)||F♭ (E)||F||G♭♭ (F)|
Diminished 7th Chord Charts
Adim7 - Cdim
C#dim7 / Dbdim7 - Edim7
Please note that all chord charts indicate different shapes in different fret positions rather than set fret positions. Generally, there are 3 different dim7 shapes and each one can be played in 4 different positions. Let's say that you like playing the third shape, and you are looking for a Ddim7 chord... as long as the shape stays intact and any one of your 4 fingers lands on a D note, you are playing a Ddim7 chord. The same applies to the other shapes.