Mike Moxcey ©2005

Building Extended Chords

Just as you can add certain notes to the basic triads to get larger chords, you can add more notes to the other chords to get extended chords. The basic extended chords are built on the dominant seventh (7) chords. To get a Ninth chord (9), you add the ninth note (or second note) of the scale to the seventh chord (not to the major seventh or minor seventh). To get a 13th chord, you add the 13th note (or 6th note) of the scale to the seventh chord.
C9  notes: C E G Bb D     A9  notes: A C# E G B
C13 notes: C E G Bb A     A13 notes: A C# E G F#
If they indicate the chord is a minor 9th (Cm9) or minor 13th (Am13), then you add the extra note to a minor seventh group of notes.
Cm9  notes: C Eb G Bb D    Am9  notes: A C E G B
Cm13 notes: C Eb G Bb A    Am13 notes: A C E G F#
You can build suspended ninth chords and minor-major 13ths and all sorts of other weird chords this way. And they can be written many different ways. You’ll just have to see what harmonizes best with the melody.

Choosing Important Notes of the Chord

One of the problems with extended chords is that can be impossible to play on an instrument with only four fretted strings such as the mandolin, banjo, or ukulele. In order to play them reasonably well, you’ll probably have to drop some notes.

The two best notes to drop are the root (I) and the 5th notes.

This may seem counterintuitive at first, but those notes are the same between every chord so playing them doesn’t really distinguish between different chords. The 3rd note is critical to distinguish between a major and a minor. Likewise, the 7th note is needed to distinguish between a dominant and a major seventh. And the extra notes such as the “sus” or “13th” are required or else, why bother?

If you’re playing with other people, you can forget about doing the root note. Someone else will be playing it. The 5th note is implied by the root so you can forget about that if you want to, also. Conversely, you can play just the basic major or minor chord if someone else can cover the extensions for you. It’s almost like a symphony where no one plays a chord. Each instrument can only play one note but together they can make a chord you have no hope to emulate on your puny little instrument.

If you’re playing by yourself, let your ear be your guide. Not every chord has to be complete in and of itself. The entire song has to hold together as a piece so choose the notes you can reach that make the song sound better.

Diminished Chord

The diminished chord is formed from the diminished scale. Just as there are only three distinct diminished scales, there are really only three distinct diminished chords. On a banjo or mandolin, you can actually make a three note Diminished chord differently from a 4-note Diminished Seventh, but they sound similar enough that you needn’t distinguish between them unless you’d like to vex someone trying to read your music (another benefit to knowing theory).

The diminished chord is made from every other note of the diminished scale. Each note is 3 frets from its neighbor.

Diminished Scale:

Frets:  -2--1- -2--1- -2--1- -2--1-
Scales: C D  Eb F  Gb Ab  A B  C 
Db Eb  E Gb  G A  Bb C  Db 
D E  F G  Ab Bb  B Db  D 

Diminished Chords:

The Diminished chord is shown as a minus sign (-) or “dim” after the chord. Any note of the chord can be considered the root chord so a These are all pronounced "C-diminished" or "B-diminished" chord.

Using the Diminished Chord

Another way of thinking about the diminished chord is as a regular seventh with every note flatted a fret except for the root.

Thus you can drop a C7 down to a Cdim:
C7: C E  G  Bb 
C-: C Eb Gb A 
Of course, on the instrument, the easiest thing to do is raise the root instead of drop all the rest of the notes.
C7 : C  E  G  Bb 
C#-: C# E  G  Bb 
A good place to use diminished chords is right before you change to the next chord. Move up one fret and use the next higher diminished chord of the chromatic scale. Thus the basic chord progression:
I / /  /  | IV / /  /   | I / /  /  | V / / / |
I / / I#- | IV / / IV#- | I / / I#- | V / / / |
Here it is in a few keys:
C / / C#- | F / / F#- | C / / C#- | G / / / | 
D / / D#- | G / / G#- | D / / D#- | A / / / | 
G / / G#- | C / / C#- | G / / G#- | D / / / | 
A good turnaround at the end of a verse or chorus also uses the diminished chord:
I I#dim VIm V7
Here it is in a few keys:
C C#dim Am G7
D D#dim Bm A7
G G#dim Em D7

Augmented Chords

The augmented chord is built off of the Whole Tone scale.
Frets: -2--2- -2--2- -2--2-
Scales:C  D E  Gb Ab  Bb C 
Db  Eb F  G A  B Db 
D  E Gb  Ab Bb  C D(same as the C whole tone scale)
Although there are only two distinct Whole Tone scales, there are four different Augmented chords.
For each of the two scales, one chord starts on the 1st note of the scale and one starts on the second. Like the diminished chord, any note of the chord can stand in for the root.
Scale one chords: C E Ab
D Gb Bb
Scale two chords: Db F A
Eb G B
Augmented chords fit in well as turnarounds on ragtime songs.

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