Generally, in music, a diminished chord is a chord which has a diminished fifth in it. More specifically, it is a three-note chord (a diminished triad) consisting of a minor third and diminished fifth above the root - if built on C, a diminished chord would have a C, an E flat and a G flat. The interval between the upper two notes is also a minor third - thus, the chord consists of two minor thirds stacked on top of one another. It resembles a minor triad with a lowered (or diminished) fifth.
Diminished chords are very cool, and easy to understand. Diminished chords serve a cadential function just like a dominant 7. Let's look at a dominant 7 chord construction in the key of C:
In the key of c the dominant chord would be a G Chord tones: G B D
To make it a dominant 7 add the F: Chord Tones: G B D F
Now let's look at the diminished chord in the key of C which would be a B Diminished: Chord tones: B D F
To make it a diminished 7 or a minor 7b5 which is how it is most commonly referred to add the a Chord tones: B D F A
Now if you look closely at the two chords G7: G B D F Bm7b5: B D F A
The only thing separating these two notes is the A and the G, so they can be used interchangably to perform the same function.
There are in reality two types of diminished chords The Half diminished which is the minor7b5: B D F A. And, there is also the full diminished chord: B D F Ab
Here is a form for each of the diminished chords.
- —– —— —— ——
- –3– —3– —1– —1–
- –2– —1– —2– —2–
- –3– —3– —2– —1–
- –2– —2– —— ——
- —– —— —2– —2–
Just like all bar chords these are universal shapes and can be moved anywhere on the fretboard and you will come out with a diminished chord as long as the shape is retained. A cool tune that uses diminished chords is ”Autumn Leaves”. You should probably get yourself a Jazz real book and go from there.
Diminished power chords
Technically speaking there really is no such thing as the diminished power chord. A power chord by definition is, as you pointed out, simply the root and the fifth of a scale. The term “power chord” is strictly a contrivance of the electric guitarist. You can, however, play two notes, one being the first, or root, and the other being a diminished fifth. This is called playing an interval. It is also a very interesting interval, theory wise, because the diminished fifth is as far away as you can get from the root. Take a look:
A, Bb, B, C, C#, D, Eb, E, F, F#, G, G#, A
When A is your root note, Eb (or D#) is your diminished fifth (or augmented fourth). It is the sixth half step from either end of the scale. This is often referred to as a tritone, because it is the third full step from the root and it takes an additional three full steps to get back to the root. It is very common in jazz and classical music but very rare in most other guitar music. It is very key in what is known as the “whole tone” scale, that is, a scale that has no half steps in it whatsoever. Here it is in A:
A, B, C#, Eb, F, G, A
A diminished chord, as I'm sure you're aware, consists of the root, the minor (or diminished) third AND the diminished fifth. If you will, it is a minor third on top of another minor third. Since the guitar, when standardly tuned, is tuned in fourths, it is almost impossible to play pure diminished chords in a moveable style. What is usually used instead is a diminished seventh, which is a bizarre chord in and of itself but truly wonderful to work with.
This is four minor thirds on top of each other. It's played on the first four strings and, in first position, it looks like this:
Ddim7:
E - 1st fret B - open G - 1st fret D - open A - don't play E - don't play
Now the fun thing about this is that because of the intervals, you can play this same chord up and down the fret board. Think about it, the notes involved in this chord are D, F, Ab, and B (which is Cb, hence the “diminished” seventh). Look where else I can play these same notes:
Ddim7 (variation 1):
E - 4th fret B - 3rd fret G - 4 th fret D - 3rd fret A - don't play E - don't play
Ddim7 (variation 2):
E - 7th fret B - 6th fret G - 7th fret D - 6th fret A - don't play E - don't play
Ddim7 (variation 1):
E - 10th fret B - 9th fret G - 10th fret D - 9th fret A - don't play E - don't play
And if this isn't wild enough, think about this - depending on what note you choose as your root, you actually have FOUR different diminished seventh chords here at your disposal:
| Chord | Root | minor 3rd | diminished 5th | diminished 7th |
|---|---|---|---|---|
| Ddim7 | D | F | Ab | B (or Cb) |
| Fdim7 | F | Ab | B (or Cb) | D (the dimished Eb) |
| Abdim7 | Ab | B (or Cb) | D (Eb dim) | F (Gb Dim) |
| Bdim7 | B | D | F | Ab |
This is one crazy subject that tends to confuse the daylights out of people. I hope to write about it sometime this winter when I have enough free time to ensure that I write it well enough for people to understand the first time!