An Intro to Diatonic Harmony
How do I know what chords sound good together? If I want to write a killer song, what mental library can I access to figure out the next chord change? A little later, we’ll take a look at what musicians call harmonic areas. This is a way of describing the relationships certain chords have with one another. To understand them, we first need to familiarize ourselves with some basics of diatonic harmony.
Diatonic harmony is a pretty cool idea that we’re all familiar with – whether we know it or not. The push and pull we feel and hear in a lot of music owes much to this system. It’s pretty easy to analyze and control. It can tell us what chords we’re allowed to play in any given key, and a little later teaches us how to break those rules. For the purposes of these lessons, we’ll start with the well known major scale as our home base.
Briefly, we can harmonize any scale and come up with a series of chords that occur naturally in that key.
Check out the G major scale here:
|Scale Degree||Note Name|
If we start on G and skip a third (skipping one note name), we have G-B. Skipping another third gives us G-B-D. That’s a G major chord. Go ahead and check all the notes in a regular old G chord. It’s just various configurations of the notes G, B, and D.
Following this logic of building triads off of every note, we’re left with the following series:
Notice that I tell you if a chord is major, minor or diminished by using upper and lower case Roman numerals. The little circle next to viio means diminished. These are all the chords naturally occurring in the key of G major. Took a lot of work to get there, huh? Sure, but the beauty of this system is that it’s movable The same concept applies to all major keys. The I chord in all keys is major, the ii chord is minor, etc.
|Chord quality||Key of G||Key of A|
A neat and tidy way to remember the order is: Ma-Mi-Mi-Ma-Ma-Mi-Dim.
To expand on the idea of “stacked thirds”, we can add a new third to the top of every triad to find which 7th chords occur in the key. Taking our I chord – GBD – and skipping a third from D to F# yields a G major 7th chord: GBDF#.
|G||Major 7 – GBDF#|
|A||Minor 7 – ACEG|
|B||Minor 7 – BDF#A|
|C||Major 7 – CEGB|
|D||Dominant 7 – DF#AC|
|E||Minor 7 – EGBD|
|F#||Half Diminished (Minor 7 Flat 5) – F#ACE|
Notice even though we’ve added new chord members to each triad, it still follows the Ma-Mi-Mi-Ma-Ma-Mi-Dim formula. Incidentally, this “stacked thirds” method is how you can build all sorts of useful chords like 9ths, 11ths and 13ths.
At this point, start experimenting with different chords in one key. For the purposes of this article I’ve stuck to G Major, but you should work those brain muscles to start figuring out the chords in different keys. We’ll talk about applications in the next installment.