From: "Mike Livengood"@mrgw.gene.com
Subject: LESSON: Diminished Chords
Tue, 18 Jul 1995 00:00:00 PST

What is a diminished chord you ask? No it's not a chord that suffers from an 
inferiority complex. A diminished chord (or more correctly called a diminished 
7th chord) is a four note chord that consists of a root, a minor third, a flat 
fifth, and a diminished 7th. You'll notice that this results in three minor 
thirds. The symbol for a diminished chord is the root followed by a small 
circle (like a degree mark) or the abbreviation dim. The diminished chord is 
best known for its unresolved tension and is therefore used in movies when the 
villain bursts onto the scene (boo hiss).

Below are a few fingerings for diminished chords:

        r m3 b5 m7
Cdim    C-Eb-Gb-A       (in this case the dim 7 is written as an A 
                         instead of a Bbb for convenience)

                                                Gdim
E----           --2-            ---             -3-  G
B--4-           ----            ---             -2-  Db
G--2-           --2-            -8-             -3-  Bb
D--4-           --1-            -7-             -2-  E
A--3-           --3-            -9-             ---
E----           ----            -8-             ---

The wild thing about diminished chords is that they repeat every four frets 
(minor 3rd). This means that the 4 notes that are in a diminished chord form 
four diminished chords, one for each root note.

So the C-Gb-A-Eb that form the Cdim also form the Ebdim, the Gbdim and the Adim.

So take the first Cdim fingering example above and slide everything up 3 frets 
to the 6th position. The notes are now.
Eb-A-C-Gb

E----
B--7-
G--5-
D--7-
A--6-
E----

Hey! Look at that! It's an Eb diminished chord but it contains the same notes 
as a C diminished.

Here are some other diminished chord notes:

Ddim    D-F-Ab-B        (includes F, Ab and B diminished chords)
Edim    E-G-Bb-Db       (includes E, G and Db diminished chords)

Believe it or not, these three diminished chords (Cdim, Ddim and Edim) include 
all the notes for all twelve dim chords!

How do we use diminished chords? (Besides in Dudley Dooright movies). 

Admittedly popular music does not use diminished chords much.(Plush by STP uses 
a Gdim in the main theme) (A friend of mine uses one in Auld Lang Syne). But 
that doesn't mean that they aren't useful in your original compositions, or for 
your theory knowledge. Here are a few progressions that you can use to try out 
a few diminished chords.

Simple #1 (use a funky jazz strum)

   C  C#dim  Dm7  G7    C  C#dim   Dm7  D#dim
E--0---0---l--5---3---l--0---0---l--5--------l
B--1---5---l--6---3---l--1---5---l--6----7---l
G--0---3---l--5---4--ol--0---3---l--5----5---l
D--2---5---l--7---3--ol--2---5---l--7----7---l
A--3---4---l--5---5---l--3---4---l--5----6---l
E----------l------3---l----------l-----------l

   C  D#dim  Dm7  G7
E--0-------l--5---3--l
B--1---7---l--6---3--l
G--0---5---l--5---4--l
D--2---7---l--7---3--l
A--3---6---l--5---5--l
E----------l------3--l


Simple #2

   C  C#dim  Dm7  D#dim   C   E7    F    Fm
E--0---0---l--5--------l--0---0---l--1----1---l
B--1---5---l--6----7---l--1---3---l--1----1---l
G--0---3---l--5----5---l--0---1---l--2----1---l
D--2---5---l--7----7---l--2---0---l--3----3---l
A--3---4---l--5----6---l--3---2---l--3----3---l
E----------l-----------l------0---l--1----1---l

   C  Ebdim  Dm7  G7      C  C#dim  Dm7   G7
E--0-------l--5----1---l--0---0---l--1----1---l
B--1---7---l--6----0---l--1---5---l--1----0---l
G--0---5---l--5----0---l--0---3---l--2----0---l
D--2---7---l--7----0---l--2---5---l--0----0---l
A--3---6---l--5----2---l--3---4---l-------2---l
E----------l-------3---l----------l-------3---l

Simple #3
                                            alternate
  C#dim    Fm6     Bdim     C    C7   Fm6     (Fm6)
E---0---l---4----l-------l--3----3--l--4--l   --1-
B---5---l---3----l--3----l--5----5--l--3--l   --3-
G---3---l---5----l--1----l--5----3--l--5--l   --1-
D---5---l---3----l--3----l--5----5--l--3--l   --3-
A---4---l--------l--2----l--3----3--l-----l   --3-
E-------l--------l-------l----------l-----l   --1-

    C     D7   G7
E---0---l--5----3---l
B---1---l--7----3---l
G---0---l--5----4---l
D---2---l--7----3---l
A---3---l--5----5---l
E-------l-------3---l

Try playing these again but instead of playing a C#dim, play an Edim (7th fret). 
Hey! sounds similar...same notes.

Try and find some resolutions to other chords that you like. I kind of like the 
way the diminished chord resolves to the minor seventh chord a half step lower 
(ie C#dim-Cm7). But there are lots of resolutions to try.

Here's a more complex (kind of jazzed up) version of the first chord progression 
using substituted chords.

Substitute

   C6 C#dim  Dm7  G13   C6  C#dim   Dm7 D#dim
E--5---0---l--5---5---l--5---0---l--5--------l
B--5---5---l--6---5---l--5---5---l--6-----7--l
G--5---3---l--5---4--ol--5---3---l--5-----5--l
D--5---5---l--7---3--ol--5---5---l--7-----7--l
A--3---4---l--5-------l--3---4---l--5-----6--l
E----------l------3---l----------l-----------l

   C6 D#dim  Dm7   G13-9
E--5-------l--5-----4--l
B--5---7---l--6-----5--l
G--5---5---l--5-----4--l
D--5---7---l--7-----3--l
A--3---6---l--5--------l
E----------l--------3--l

Now go get that jazz guitar and some dark shades...