Is a minor Seventh Chord basically just a combination of a “minor Triad” and its Relative “Major Triad”, (or a combination of a Major Triad and its Relative minor Triad)?
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1It's not wholly clear what you're asking. Are you asking to confirm a property of the notes in the chord, or are you asking if that's how the chord was "invented" — that is, the theoretical basis for the chord?– AaronCommented May 28 at 3:40
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For example, the “a minor Seventh Chord” looks like it is basically just a combination of the “a minor Triad” and the “C Major Triad”.– Dave LittleCommented May 28 at 3:44
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1So, you're just looking for confirmation of that observation?– AaronCommented May 28 at 4:00
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Yes, that is correct.– Dave LittleCommented May 28 at 4:13
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7 Answers
All m7 chords comprise minor and major triads from relative keys.
The tonic notes of relative major and minor scales are always a minor third apart. Put another way, any minor third can represent the tonic notes of a minor scale (the lower note) and its relative major scale (the upper note).
A minor chord has the structure m3 + M3, and major chord has the structure M3 + m3.
A minor seventh chord has the structure m3 + M3 + m3. So, the lower triad of a minor seventh chord is a minor triad (m3 + M3), and the upper triad of a minor seventh chord is a major triad (M3 + m3).
These two triads, because they're separated by a minor third, represent the roots of relative minor and major keys.
Let's take actual notes to explain. We'll be in key C, with its relative minor Am.
The triad notes of Am are A C and E. The triad notes of C major are C E and G. Playing all four notes will produce what you ask about - Am7. So, yes, your observation is correct. Except - those same four notes could also be determined as the chord C6! Although you could never superimpose two triads (in root position) to produce that one.
Of course, using a formula of 1,3,5 from any minor, and superimposing 1,3,and 5 of its relative major will produce what you suspect in any key, of all 12 keys (or is that 24..?!).
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your point about C6 seems important but I'm not sure I understand correctly. Why is not C6 a combination of the same two triads as Am7? The two triads in the analysis for Am7 are root positions in the two respective scales, same as if we thought C6 comes from the C major and the relative minor. Am I confused?– Davy5003Commented Jun 7 at 7:14
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The notes are identical for C6 and Am7, true. But they can't be overlapped as triads in root position, as G and A are next to each other.– TimCommented Jun 7 at 9:02
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sorry if I seem obtuse but is the key word here 'overlapped'? The OP uses 'combination'. I get Am (A C E) + C (C E G) = Am7 with C and E common while C (C E G) + Am (A C E) = C6 and this could be interpreted as C and E sounded simultaneously in two octaves. Is that it? On a guitar we often cannot respect the order of notes in a triad and playing C6 as C E G A can be tricky. Why would overlap or superposition be important here?– Davy5003Commented Jun 8 at 5:49
I think a m7 chord is 'basically' an extended minor triad. The fact that the upper structure coincides with the relative major's tonic triad is interesting, but not particularly important.
Yes. Take any m7 chord in its most basic version. Remove the bottom note, you have a major chord, remove the top note you have a minor chord. Maj7 chords work similarly but backwards.
All minor seventh chords are transpositions of one another, so let's take Am7 for an example. It just looks more intuitive with letters rather than numbers.
The Am7 chord consists of A, C, E, G. (Root, minor third, fifth, minor seventh.)
The Ami chord consists of A, C, E. (Root, minor third, fifth.)
The relative major of A minor is C major.
The C chord consists of C, E, G. (Root, major third, fifth.)
Ami ∪ C = {A, C, E} ∪ {C, E, G} = {A, C, E, G} = Am7
Q. E. D.
A minor seventh chord is nothing more than just a minor triad with a minor seventh added to it.
So a root note, minor third, perfect fifth, and minor seventh.
I think there are two main ways to think of the generation of seventh chords, including minor seventh chords.
- Stacking thirds, and the basic stacks are diatonic. This would be the vertical or harmonic conception.
- The seventh is formed by some non-chord tone motion like a suspension or passing tone. The would be the contrapuntal conception.
You might add a third category, which is a base triad plus a seventh. This is used for seventh chord nomenclature in some theory books. Ex. the minor major seventh chord is a minor triad base combined with a major seventh, in C minor C E♭ G B♮.
Your concept of combining the two chords is like the third category I listed, but I don't remember seeing that exactly in any theory books. Nevertheless, it's clear what you mean.
answered Jun 5 at 20:56
