Chord Families

cdkrugjr said:

That's actually a pretty complicated question. There are Many different approaches that have been used over the years. Since you're talking "Triads" (three-note chords), I'll stick to basics, but there's a lot more where that came from.

Okay, we like Roman numerals for this. Sometimes we distinguish between Major and minor with capitalization. That wasn't how I was taught, but it's out there. The nice thing about standards is that there are so many to choose from.


In Major keys, as you say, it goes like this:
1-I-Maj; 2-ii-min; 3-iii-min; 4-IV-Maj; 5-V-Maj; 6-vi-min; 7-vii-diminished.

In minor, we take the roots from the Natural minor, but the chord notes from the Harmonic minor. That raises the 7th degree, which conveniently makes the V chord a major again.

1-i-min; 2-ii-dim; 3-III-M (#5); 4-iv-min; 5-V-Maj; 6-VI-Maj; 7-vii-dim

I've seen III given as both "Major" and "Augmented" (#5). Both are "correct" depending on whose theory you're citing, though most of the songs we play use Major.

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cdkrugjr said:

That's actually a pretty complicated question. There are Many different approaches that have been used over the years. Since you're talking "Triads" (three-note chords), I'll stick to basics, but there's a lot more where that came from.

Okay, we like Roman numerals for this. Sometimes we distinguish between Major and minor with capitalization. That wasn't how I was taught, but it's out there. The nice thing about standards is that there are so many to choose from.


In Major keys, as you say, it goes like this:
1-I-Maj; 2-ii-min; 3-iii-min; 4-IV-Maj; 5-V-Maj; 6-vi-min; 7-vii-diminished.

In minor, we take the roots from the Natural minor, but the chord notes from the Harmonic minor. That raises the 7th degree, which conveniently makes the V chord a major again.

1-i-min; 2-ii-dim; 3-III-M (#5); 4-iv-min; 5-V-Maj; 6-VI-Maj; 7-vii-dim

I've seen III given as both "Major" and "Augmented" (#5). Both are "correct" depending on whose theory you're citing, though most of the songs we play use Major.

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ubulele said:

Minor harmony uses three base scales simultaneously (or one natural scale with two intervalic sequence mutations), so you get even more variety in the minor chords than cdkrugjr mentions. The harmonic minor scale (created by changing the minor 7th into a leading 7th) is a bit of a misnomer; its main effect is to change the V chord from minor to major, but both types of V chords may be used, even in the same piece. The two other chords generated by the 7th alteration of "harmonic minor" (viz, IIIaug and VIIdim) are seldom used as given. Instead, the less dissonant chords from the natural minor scale are used: major III and major VII (whose root is the minor 7th of the scale, not the major 7th).

In minor harmony, this major VII plays a much bigger role than it does in major mode, where it mostly functions as a rootless V7 chord. In fact, there are many minor (and Mixolydian) songs where the harmony consists of only Im and VII chords. Of course, this could also be analyzed as Im and (rootless) Vm7.

Also, in minor, the II chord tends to be altered from dim into a simple minor.

In summary, the most typical chords in minor are:
Im
IIm, sometimes IIdim
III, sometimes IIIaug
IVm
V or Vm
VI
VII
#VIIdim


On a related note, in major mode, the II chord is often major rather than minor when it leads to the V chord (and in this case, it's often a dominant 7th as well). That's because II has the same relation to V as V does to I. Technically, it's a "V of V" chord, as if you'd temporarily modulated into the key of the V chord's root. Similarly, you may encounter III and VI in major rather than minor form when they lead to VI and II respectively.

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Redeyejedi said:

thank for the detailed explanations.
days ago, this made less sense than launching lunar landings but after a some reading, some of this is beginning to make sense to me. the lightbulb hasn't quite 'gone on' so to speak, but at least the some light to shed on the topics so i am seeing them more clearly.
- Aaron

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