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In the previous Pomodoro, we saw how we can build chords by stacking up the root, the 3rd and the 5th note of the modes of the scale, resulting in 3 note chords. 3 note chords are mostly used in folk music and its derivatives like bluegrass.
In jazz however 4 note chords are used. You can hear it already in the swing music of the ‘20s of the previous century. But as we’ve mentioned in the previous Pomodoro, there’s also one 4-note chord used in folk music : the dominant 7th chord.
Building a 4-note chord is childishly easy : you take a 3-note chord, and you add the 7th of the mode. So, that gives in the key of C the following chords :
mode root | chord notes (1 – 3 – 5 – 7 of the mode) | chord name | indication |
C | C – E – G – B | C major 7 | C+7 or Cmaj7 |
D | D – F – A – C | D minor 7 | D-7 or Dmin7 |
E | E – G – B – D | E minor 7 | E-7 or Emin7 |
F | F – A – C – E | F major 7 | F+7 or Fmaj7 |
G | G – B – D – F | G 7 | G7 |
A | A – C – E – G | A minor 7 | A-7 or Amin7 |
B | B – D – F – A | B half diminished | B-7b5 |
I left out the roman numeral notation, because in my brief big band jazz amateur guitarist career, I’ve never seen a music sheet with roman numeral notation.
As always, when you use another key, the root of the modes and the chords will change, but not their major or minor characteristic.
Some points to notice :
- The same remarks as for the 3-note chords remain : when you play a 4-note chord, notes and their octaves can be repeated. However, most 4 note chords on the guitar are played using only 4 strings (e.g. string 6 for the bass note, strings 2-3-4 for the other notes).
Inversions are also allowed : 1 – 3 – 5 – 7 or 3 – 5 – 7 – 1 or 5 – 7 – 1 – 3 or the 3rd inversion 7 – 1 – 3 – 5.
- While it was ok to call the 3-note chord VII “diminished” (and leave out the “half” part), that’s not the case of for the 4-note VII chord ! Here, you HAVE to call it half diminished, because there is also a 4-note full diminished VII chord. The difference is that the half diminished VII chord has a minor 7, and a (full) diminished chord has a diminished 7. E.g. a (full) diminished B chord = B – D – F – Ab !
If you compare this with the VII chord in the table above, you will notice that the minor 7th A has dropped to Ab. An interesting feature of this chord is that every note is separated by the exact same interval 1+1/2 step, so it can repeated upwards or downwards : B – D – F – Ab – B – D – F – Ab – etc. ! It’s the only chord for which this is the case.
Without going further into detail, I can tell you that you find the (full) diminished chord when you build chords based on the minor scale. If you want to try out for yourself, don’t forget to use the minor harmonic scale, as mentioned in Pomodoro 8. I assure you : you will find some exotic chords there !
- A neat trick if you want to become a (big band) jazz guitarist : since the piano and/or the bass will play the root and the 5th of the chord, you don’t need to play them. So, you can stick to the 3rd and the 7th’s of the chord. They happen to be the most characteristic notes of the chord, so it’s great if you can let them shine on the guitar. Now, the trick : you can play the 3rd and 7ths of ALL THE CHORDS (major, minor and diminished) in ALL THE KEYS, only using strings 3 and 4 (the strings in the middle) !
A chord that is worth exploring a bit more is the V-chord, also known as the “dominant 7”.
First, the word “dominant”. In the diatonic scale, each note has a function. I don’t quite know the purpose of these names, but here they are in a table :
note in scale | function name |
1 | root or tonic |
2 | supertonic |
3 | mediant |
4 | subdominant |
5 | dominant |
6 | submediant |
7 | leading tone (leads to root) |
The two most important are the root (1st note) and the dominant (5th note). It’s called the dominant, because if you play the dominant 7, it’s like it is “demanding” to be resolved to the root chord.
E.g., in the key of C, when you play G7 (dominant 7), the chord “demands” as it were to be solved to C, the root chord. It’s this “demanding” characteristic that makes the V chord dominant.
In blues, very often all the chords are played with a “dropped 7” (the difference between a Gmaj7 and a G7 is indeed a dropped 7). A blues in E for instance is very often played as : E7 – A7 – B7.
The last point to discuss is the question : what after adding the 7th note to the chord ? Indeed, in jazz, chords don’t stop on the 7th note. Many a times, more notes are added : 9ths, 13ths, and all sorts of augmented and lowered notes.
They are called “ornaments” because they don’t really change the general “mood” of the chord, they just add color to it.
Some well known chord ornaments are
- the 6/9 that you can play whenever you play maj7. E.g. if you play Cmaj7, you can play C6/9.
- the 13th that you can play together with or instead of the dominant 7. So in stead of G7, you can play G13. (13 is the 6 above the octave of the root).
In extreme situations (free jazz), the entire chromatic scale is used as chord ornaments. But then as Charles Ives said, you have to take your dissonance like a man ! I don’t know about you, but I am certainly not there yet !
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This concludes this series of Basic Music Theory in 11 Pomodoros.
The last thing I want to say is that, for me Basic Music Theory can be compared to a CV of a person. This CV (if honestly written) will tell you a great deal about the facts and figures, but you won’t really know who that person is : what is her/his personality ? To really know that person, you have to meet her/him in person.
It’s the same with Music. You can read all the music theory books you want, it still while singing or playing an instrument that you get to see a tip of the veil of the mystery that Music is. A mystery that is worthwhile to explore and discover for a lifetime !
I wish you all a happy continuation of your exploration adventure !
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