music

just my personal notes about music theory

what is a chord

2+ notes played together

distance from root note

distance between any two adjacent notes in any chord should be either min3 or maj3 (tertian harmony)

distances between any two notes:

min2   - 0.5 steps
maj2   - 1   steps
min3   - 1.5 steps
maj3   - 2   steps
perf4  - 2.5 steps
dim5   - 3   steps
perf5  - 3.5 steps
aug5   - 4   steps
dim7   - 4.5 steps
min7   - 5   steps
maj7   - 5.5 steps
octave - 6   steps

chord long names

full name of any chord: root_note min3/maj3 dim5/perf5/aug5 min7/maj7 min9/maj9/aug9 dim11/perf11/aug11 min13/maj13/aug13

diminished chord:  note min3 dim5
augmented chord:   note maj3 aug5
dominant chord:    note maj3 perf5 min7
maj seventh chord: note maj3 perf5 maj7
min seventh chord: note min3 perf5 min7

• suspended chords: instead of min3/maj3 use sus2/sus4 (which means maj2/pef4), the rule about adjacent notes doesn't apply here
• 9/11/13 chords: the rule about adjacent notes might not apply here (non tertian harmony)

chord short names

as based on root note C

C          - C maj3  perf5
Cmin       - C min3  perf5
Cdim       - C min3  dim5
Caug       - C maj3  aug5
C7         - C maj3  perf5 min7 (dominant)
Cmaj7      - C maj3  perf5 maj7
Cmin7      - C min3  perf5 min7
Cminmaj7   - C min3  perf5 maj7
Chalfdim7  - C min3  dim5  min7
Cdim7      - C min3  dim5  dim7
Caugmaj7   - C maj3  aug5  maj7
Csus       - C perf4 perf5
Csus2      - C maj2  perf5
Cmin9flat  - C min3  perf5 min7 min9
Cmin9sharp - C min3  perf5 min7 aug9 ???

chord inversions

root position - normal chord
1st inversion - root_note one octave higher
2nd inversion - root_note and 3rd - one octave higher
3rd inversion - root_note and 3rd and 5th - one octave higher

what is a key?

just set of preferable notes that sound good together

rule of thumb about naming: you can play a scale, but you cannot play a key

major key

all notes in a chord must belong to a key

any major key is built as:

root_note + 1 step + 1 step + 0.5 step + 1 step + 1 step + 1 step + 0.5 step
    1st       2st      3st       4st       5st      6st       7st     1st + octave

chords based on notes in scale:

1st - major chord
2st - minor chord
3st - minor chord
4st - major chord
5st - major chord
6st - minor chord
7st - diminished chord

minor key

same as major, but start from 6st

chords based on notes in scale:

1st - minor chord
2st - deminished chord
3st - major chord
4st - minor chord
5st - minor chord
6st - major chord
7st - major chord

chord progressions

maj 1-4-5
maj 1-6-4-5
maj 1-6-2-5 ???
maj 2-5-1
min 1-6-7
min 1-4-7
min 1-4-5
min 1-6-3-7
min 2-5-1

use chord inversions to bring notes closer together

https://www.hooktheory.com/trends

modes

Take major scale of any note, but start from note number X and get this modes:

• ionian (I) aka major scale
• dorian (II) aka like minor with raised 6th note
• phrygian (III) aka like minor with lowered 2th note
• lydian (IV) aka major with raised 4th note
• mixolydian (V) aka major with lowered 7th note
• aeolian (VI) aka minor scale
• locrian (VII)