Fuego":iyqi68b7 said:
Honestly I don't think his question was answered. The reason a major third is what it is, is because it's the 3rd note up the major scale from the root. Minor 3rds,7th etc is that number of notes up the minor scale. Perfect 4th and 5th are perfect because they are both the same in both minor and major scales. Sorry fir the necro bump.
Not quite that would make phrygian the go to minor and make the diminished 5th in locrian a minor 5th.
Perfect interval, unison, P4th, P5th
Minor, 2, b3, b6, b7
Major, 2, 3, 6, 7
Diminished, 3, 4, 5, 6, 7
Augmented, 2, 3, 4, 5, 6
Why? We can use enharmonic names and not worry. I mean G melodic minor is G, A,Bb,C,D,E,F#... spelled "correct" it'd be Abb, Bbb, Cbb, Dbb, Ebb, Fb, Gb...
What nonsense.
But there is a use if you know that a Dm7 arpeggio is d f a c making it a Db and thinking Db Fb Ab Cb keeps the naming logic in check.
Also intervals invert and add up to 9 (8 numbers per octave starting on 1).
So c to a is either M6 or m3
Or C to F# aug4 or Dim5 etc...
As for 13 vs 6 etc...
In scales we usually reference up to the octave in chords the 13.