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Hello there,

This might seem like a silly question, but I've been practicing diminished chords, and I've not seen any minor diminished chord being labelled specifically with its minor indication. Is it because diminished chords on the tonic or specific notes are always formed from minor chords?

Like G#m is G#, B, D#.

But when it's diminished as G# B D, it is simply written as G#dim.

Then how do you differentiate G#min as G# B D and not G# B# D?

Or is it because B# and D now have an interval of a major second it is not labelled as a minor triad?

Otherwise shouldn't G# B# D be labelled as G#dim and G# B D as G# m dim (G# minor diminished)?

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Diminished chords are not a variety of minor chord; the two types are entirely separate entities.

The types of chords you're practicing are defined as being made up of as combinations of major thirds and minor thirds. Triads – three-note chords – each contain two such intervals. Thus, there are four possible chord combinations.

  • M3 + M3 = Augmented chord
  • M3 + m3 = Major chord
  • m3 + M3 = Minor chord
  • m3 + m3 = Diminished chord

Following the G# examples:

  • G# B# Dx = M3 + M3 = G# Augmented
  • G# B# D# = M3 + m3 = G# Major
  • G# B D# = m3 + M3 = G# Minor
  • G# B D = m3 + m3 = G# Diminished

These are the four basic triads recognized by the theory. Other combinations of notes, like G# B# D (M3 + d3) are not recognized as basic triads and would be defined according to their function within a larger musical context.

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  • Is "basic triad" an established term? E.g. would you call any two stacked thirds a triad even if it's not any of the four basic triads you list? Oct 27 at 14:59
  • @Divide1918 Sus chords are not considered "basic triads" within the theory. They are chords defined by context. However, in the way you're asking, G# B# C# would be a G#Sus chord (also called G#Sus4).
    – Aaron
    Oct 27 at 14:59
  • @user1079505 Yes and no. "Basic triads" is a recognized term. Tonal theory recognizes "basic triads" as stacks of major and minor thirds. The inclusion of diminished or augmented thirds would not be recognized as "basic triads". Seventh chords are similarly defined: as stacks of three major or minor thirds.
    – Aaron
    Oct 27 at 15:00
  • my question is, if you use term "basic triad", are there therefore triads which are not basic triads? Do you call G# B# D a "nonbasic triad"? Oct 27 at 15:01
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    @user1079505, I think the distinction you're looking for is diatonic triad. When the term triad is used the general understanding is diatonic triads. G# B# D is three tones, but not diatonic, it has a non-diatonic diminished third B# D. Major, minor, and diminished triads are obviously diatonic. But, the augmented triad has a sort of spotty history. It isn't quite diatonic, you only get that type of triad with accidentals. Oct 28 at 12:59
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Diminished chords and minor chords are two distinct types of chords. A minor chord (technically, a minor triad) is made of the root, minor 3rd, and perfect 5th, whereas a diminished chord (again, technically a diminished triad) is made of the root, minor 3rd, and dimished 5th (one semitone lower than perfect 5th).

So {G# B# D} is not G#dim. {G# B D} is G# dim. There's no chord type known as minor diminished. So you cannot label a chord as 'm dim'.

(Note that the other answers may use different definition for the chord types than me, but it's easy to check that they are equivalent.)

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  • Really, all this talk about defining chords as stacks of thirds is just confusing. The identity of the interval between the third and the fifth of the triad is not nearly as useful a fact as the identity of the interval between the root and the fifth. +1.
    – phoog
    Oct 28 at 13:24
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There are four type of basic triads and they strictly refer to the following combination of intervals (and their inversion):

  • minor (comprising of minor and major third)
  • major (major and minor third)
  • diminished (two minor thirds)
  • augmented (two major thirds)

A chord like G# B# D is therefore not a basic triad. We may consider what might be a chord symbol for this chord, and that would be G#(b5), which would read "G# major with flattened 5".

I would say it's a rarely used chord, but in jazz you may encounter G#7b5 (G# B# D F#), or G#maj7#11 (G# B# Cx D# Fx (A#)). Note also that more typically root for this chord would be Ab rather than G#, which would use less accidentals.

A potential source of confusion are two frequently used chords, other than triads, which use the word "diminished".

  1. Half-diminished chord: G# B D F# which is notated as G#ø. However, it is often also notated as G#m7b5, "G# minor seventh with flattened fifth", despite it includes G# diminished triad.
  2. Diminished seventh chord: G# B D F which is notated as G#o7. In jazz nomenclature where sevenths are played on regular basis "7" is sometimes omitted from the notation, so G#o7 and G#o are synonymous. On the contrary in classical nomenclature G#o refers strictly to a diminished triad, and if you decide to add the seventh it's not specified whether it should be G#o7 or G#ø. For instance a diatonic triad built on the (raised) seventh step of a major (minor) scale is diminished, viio, but a diatonic seventh chord would be half diminished in major and diminished seventh in minor.
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  • The full name is "half-diminished seventh chord," because it differs from a diminished seventh chord by having half as many diminished intervals -- one instead of two. Omitting "seventh" doesn't create any ambiguity, but it does cause confusion. Of course, the name "half-diminished seventh chord" is also a bit confusing because the seventh is neither a diminished seventh nor a half-diminished seventh (which doesn't even exist).
    – phoog
    Oct 28 at 13:21
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    @phoog right, and a symbol G#ø7 is also in use. The point I wanted to make is that it is also called minor seventh chord with flat 5, which may contribute to the specific confusion OP reported. Oct 28 at 13:31
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I think you need to review some fundamentals about the triad types and their practical origin.

First you must understand the foundation is the diatonic gamut. You can describe that several ways but a common one is to say it's the white keys of the piano, or C major, the group of pitches CDEFGABC.

From that selection of tones you stack up thirds on each tone to create triads, like this...

enter image description here

...notice it is the triad on B on the VII seventh scale degree, the leading tone, which is the diminished triad. It is the only triad of the group that is diminished. The leading tone triad is the fundamental diminished triad. In terms of stacked thirds it is two minor thirds, but in terms of the diatonic gamut it is the particular quality of the triad on the leading tone.

Minor key music is more complicated, because accidentals are used in combination with a key signature, but the basic diatonic harmonies in minor will be...

enter image description here

...notice now the triad on B is on the II second scale degree, and also the VII seventh scale degree takes a sharp. Both the II and VII chords are diminished in minor keys.

Notice also that the augmented triad doesn't appear in these particular diatonic chords. We can skip over the details of that and simply say there are four triad types:

  • major
  • minor
  • diminished
  • augmented

The two patterns of diatonic chords above can be transposed into any key.

Lower case roman numerals and the o circle sign are often used to label diminished chords, like viio and iio, but sometimes you will see only upper case Roman numerals used and the chord qualities are understood from the major/minor context.

Diminished chords are not a kind of minor chord. Yes, both the minor and diminished chords have a minor third, but they a considered different types of chords.

The various qualities of triads come from the diatonic chords and their position in the diatonic scale, the intervals between the tones in those positions, determines the triad qualities.

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  • Minor key music doesn't need to be 'more complicated' - and doesn't need that raised leading note - o.k. it's often used, but not obligatory!
    – Tim
    Oct 28 at 8:45
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    @Tim, it isn't about minor "needs to be complicated," it just is compared to major. Basic major harmony can be purely diatonic, but basic minor key needs the accidentals. That chromaticism confuses many beginners. I'm speaking of the common practice harmony as taught in typical harmony textbooks. I'm giving the OP a practical heads up for minor keys. Oct 28 at 12:50
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    In "common practice" theory, the raised leading tone is not in fact optional in a perfect cadence in a minor key.
    – phoog
    Oct 28 at 13:16
  • @Phoog, exactly. And I think it can be extended back before common practice. In Renaissance music accidentals (musica ficta) were used to make leading tones. In that style a mode like dorian would get a raised leading tone for a final cadence. This is not theoretical mumbo-jumbo, the leading tone in minor mode is a very, very, very old practice. Oct 28 at 13:20
  • I somehow forgot to tag @Tim in my previous comment. And yes, the raised leading tone in Dorian mode (and mixolydian!) is one of the things that gave rise to the common practice period, but as you note it began hundreds of years earlier.
    – phoog
    Oct 28 at 13:29
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Don’t look for too much deep logic in this. Just be aware that a major triad with a lowered 5th is called C(♭5), a minor triad with a lowered 5th is called Cdim.

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