What is the difference between an augmented and diminished triad?

Answer 1

Augmented and Diminished triads are opposites.

Augmented triads are built from Major chords

Diminished triads are built from minor chords

Augmented chords have a raised 5th. (ex: c-e-g#)

Diminished chords have a lowered 3rd to make them minor; then also have a lowered 5th. (ex: c-e^{b -} g^b)

Answer 2

A Major triad consists of a major 3rd (root to middle note) and a minor 3rd (middle note to top note) that is stacked on top of the major 3rd. An example of a major chord would be F - A - C

Augmentation means to get bigger. Unlike a Major triad, an Augmented triad consists of 2 major 3rds stacked upon each other (major 3rd between the root and middle note, and major 3rd between the middle note and top note). To make a triad augmented from a major triad, raise the fifth or top note by a half step. For example, if you want to make the major triad of F - A - C into an augmented triad, the top note C would be raised a half step and the augmented triad would be F - A - C#.

A Minor triad consists of a minor 3rd (root to middle note) and a major 3rd that is stacked on top of the minor 3rd. To change a major triad to a minor triad, lower the 3rd or middle note by a half step. An example of a minor chord would be F - Ab - C where the middle note A in a major triad is lowered a half step to Ab.

Diminish is to make smaller. Unlike a minor triad, a Diminished triad consists of 2 minor 3rds stacked upon each other (minor 3rd between the root and middle note, and minor 3rd between the middle note and top note). To make a triad diminished from a minor triad, lower the fifth or top note. To make a triad diminished from a major triad, lower the third (middle note) and fifth (top note). For example, a diminished triad would be F - Ab - Cb where the third (middle note) and fifth (top note) are lowered by a half step compared to the major triad (F - A - C).

Answer 3

Using Interval, Augmented is triad with major 3rd over major 3rd from root note while a diminished triad is minor 3rd over minor 3rd from root note.

Example: C E G# Augmented

C Eb Gb Diminished

Answer 4

Diminish means to make smaller and augment means to make bigger.

From a major triad to a diminished triad- Lower the third and the fifth. This will make the notes closer together so we are diminishing the chord.

From a major triad to an augmented triad- Raise the fifth. This will make the notes further apart so we are augmenting the chord.

Answer 5

I would suggest thinking about this as stacks of thirds rather than as changes to another triad. As I’m sure you recall:

Major Chord: Built as a Major 3rd between the root and the middle note and then a Minor 3rd between the middle and top note

Minor Chord: Built as a Minor 3rd between the root and the middle note and then a Major 3rd between the middle and top note

SO then

Diminished Chord: Two Minor 3rds

Augmented Chord: Two Major 3ds

This is how you would describe the four basic triads theoretically and it has the benefit of not needing to be referenced to another chord.

Example: Exam says “Build a diminished triad on the following note” and there’s a D written. You’d just write a minor third (An F) and then another minor third (An Ab) and you are done. It helps you know what enharmonic notation to use. Here, F to Ab is a minor third…and F to a G# is an augmented second and would NOT be correct .

I’m not suggesting the previous answer is wrong, simply incomplete.