A dim Piano Chord

Piano Diagram of A dim in Root Position

The A dim chord is the diminished triad built upon the A key. It is built by combining the Root note (A), the minor 3rd (C), and the diminished 5th (Eb) notes from the A scale. Keep reading to learn more about the music theory behind this chord.

 

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A dim Chord Inversions

 

The A dim chord has a total of 2 inversions:

 Piano Keyboard Diagrams

 

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Music Theory and Harmony of A diminished

 

What are Diminished Chords?

In music theory, diminished chords are classified as triads just like major, minor, and augmented chords. A diminished triad is a chord that has a root note, a minor 3rd, and a diminished 5th. They are often abbreviated with a small circle (°) or the letters “dim”. For example, an A diminished chord would be written as A° or Adim.

The interval between the root and the diminished 5th is called a “tritone” interval and creates a dissonant sound that adds tension and instability. Diminished triads are commonly used as transitional chords, leading to more stable chords.

Different types of Diminished Chords

1. Diminished triads are usually considered unstable and are often used as transitional chords that create tension and lead to a more stable chord.
2. There are also diminished seventh chords, which include an added diminished seventh interval above the root note. These chords are often written as °7 or dim7. They can also be used as a substitute for dominant 7th chords.
3. Additionally, there are half-diminished chords (also known as minor seventh flat five chords), which include a minor seventh interval instead of a diminished seventh.

 

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Building the A dim Chord: Different Approaches

Starting from a Major Chord

The formula for a diminished chord is R, m3, d*5.

*The diminished 5th is one half-step lower than a perfect 5th. It’s called “diminished” instead of “minor” just for naming conventions.

 

 

 

To build a diminished chord, you begin by selecting the root note, the 3rd note, and the 5th note of the major scale. Next, you lower the 3rd and the 5th note by one half-step.

So, if you want to build an A diminished chord, you would start with the A major chord, which consists of the notes A, C#, and E. Then, you would lower the third note, C#, by one half-step to get C and lower the fifth note, E, by one more half-step to get Eb. The resulting notes, A, C, and Eb, form the A diminished chord.

 

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by Combining 3rds

Alternatively, a diminished chord can be built by stacking two minor 3rd intervals on top of each other. To get this chord, you begin with the root note and then raise it by a minor 3rd. Next, you raise the third note by another minor 3rd. The resulting chord will consist of three notes that are spaced an equal distance apart.

m3 + m3 = diminished Chords

To form an A dim chord, you start with the root note A and raise it by a minor 3rd to C. Then, you raise the third note C by another minor 3rd to Eb. This results in an A dim chord consisting of the notes A, C, and Eb.

 

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How to Use A dim in a Chord Progression

 

Harmonic functions describe how chords sound together in a specific key and context. In Western music, there are seven main harmonic functions, one for each note of the diatonic scale. Major chords are represented by capitalized Roman numerals, while minor chords are represented by lowercase ones.

The tables below show the G minor scale and its relative major scale, both of which include an A diminished chord. The A diminished chord is found on the second scale degree (II) in the G natural minor scale and on the seventh scale degree (VII) in the Bb major scale. However, for a more comprehensive list of its uses, please refer to the dim7 tables, where I delve deeper into some of the features of these chords.

 

on Natural minor Scale

• Supertonic chord in G minor

 

on Major Scale

• Leading tone chord in Bb Major

 

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A dim in G Minor

In the key of G minor, the A diminished chord serves as the supertonic chord, which is the chord built on the second degree of the scale. It is often used as a passing chord to create movement between other chords in a progression.

 

A dim Chord Progressions as ii degree

Here are some examples of chord progressions that feature the A diminished as the supertonic chord.

ii iv V i

In minor keys, the fifth degree (v) is often replaced with a dominant 7th chord (V⁷) or a major chord (V) in the context of triads. This chord is derived from the harmonic minor scale and is commonly used in this position.

 

iv ii i

 

VII ii i

ii V i

 

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A dim in Bb Major

In the key of Bb major, the A diminished chord serves as the leading tone chord, which is built on the seventh degree of the scale. The leading tone chord is often used to create a sense of tension and resolution as it strongly pulls towards the tonic chord, which is the Bb major chord in this case.

 

A dim Chord Progressions as vii degree

The following chord progressions feature the A dim chord as the leading tone:

V vii I

 

I IV vii iii vi ii V I

 

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Alternative Names for A Diminished

• A°
• Adim
• A diminished

 

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