When learning music theory, the term diatonic will undoubtedly come up. Let's discuss what it means and how was can think about it when composing and producing our music!
What does diatonic mean exactly? When I was first told about diatonic playing, I thought it meant picking a scale and playing only the notes from that scale. Which it does, but you can only pick one scale when you're playing diatonically. The diatonic scale.
The diatonic scale is defined as a heptatonic scale (having 7 notes) with 5 whole tone intervals and 2 halftone intervals, in which the halftone intervals are spaced as far apart as possible (three whole tones and two whole tones separated by half tones). This doesn't give us much choice in creating diatonic scales… We are left with only one scale with the following intervals:
Looks awfully familiar. The diatonic scale is indeed our most important scale, the Major Scale!
Since the diatonic scale is only defined by its intervals, and not by any specific scale degrees, it includes all of the Major Scale's modes.
The Diatonic Scale Is Essentially The Major Scale (And Its Modes)
The major scale is the basis of functional harmony, and its modes can be used to great effect in modal harmony. And so the diatonic scale is a great base for common types of harmony! Let's first look at functional harmony.
A Note On Functional Harmony
Functional harmony means that each chord has a function within a key. It is based on the major scale's 7 notes and therefore there are 7 chords, each with a function. Let's look at the (seventh) chords in C Major
- The 1 chord: I: Cmaj7 = C E G B function = tonic
- The 2 chord: ii: Dmin7 = D F A C function = predominant
- The 3 chord: iii: Emin7 = E G B D function = tonic ext/sub
- The 4 chord: IV: Fmaj7 = F A C E function = predominant
- The 5 chord: V: G7 = G B D F function = dominant
- The 6 chord: vi: Amin7 = A C E G function = tonic ext/sub
- The 7 chord: vii: Bmin7♭5 = B D F A function = dominant
Basically, functional harmony is all about tension and resolution. In theory, we increase the tension moving from tonic to predominant to dominant, and then resolve that tension by returning back to the tonic.
Our most common chord progressions in western music are combinations of these functional, diatonic chords:
I – IV – V: Very popular in Blues and Rock/Punk
ii – V – I: The most common progression in Jazz
I – vi – IV – V & I – vi – ii – V: Very common in Popular western music
I – V – vi – iii – IV – I – IV – V: The “Canon” progression
All these progressions and many more come from playing diatonically!
A Note On Modal Harmony
Modal harmony requires that we create a tonic (a new 1 chord). We still use the diatonic scale when playing modally in the major scale, but we really focus on enforcing a ‘pseudo-tonic'. Say, we play in the mode of Dorian, built from the 2 chord referenced above. We could play all the chords of functional harmony, but we want to focus on the 2 chord and not add too many others in order to enforce that we are indeed in Dorian. Otherwise, it just sounds like we're playing functionally.
So modal harmony is created by enforcing the mode we are in. And we enforce that mode by not straying from the ‘pseudo-tonic' for too long.
Both functional and modal harmony can be diatonic if we use only the notes of the parent diatonic (major) scale.
Let's check out an example
The intro is played diatonically in the key of G Major. So I'm only using the notes found in the G Major Scale. The phrase, however, starts and stops on the outlined chord of Emin7, and therefore it sounds slightly like I'm playing in E Aeolian (the 6th mode of G Major). Check out the intro synth stem:
In the audio above, the notes are:
E G D E' A F# – B D A' B' E' C D F#' C' D' G' E' E” -repeated
All of these notes are in G major and so it is the riff is said to be diatonic!
Some “Add-ons” To Writing Diatonically
Listen to the guitar stem for the same song. I think of the guitar line as arpeggiated diatonic seventh chords without the fifth. The guitar, therefore, goes through
Emin7 – F#min7♭5 – Gmaj7 – Amin7 – Bmin7 – Cmaj7 – D7 – Emin7 – repeated.
Notice that the guitar slides between notes. We could argue that this line is not diatonic since it's technically passing through the chromatic scale (which is made up of all the notes in western music theory) on its way from one diatonic note to another. For example, when the guitar slides from the third note D up to the fourth note E, the note D#/E♭ is sounded (regardless of how little time it's sounded).
Then It's Not Diatonic?
This is where I argue that diatonicism is much better as a theoretical framework for thought than a practical application in music. There's so much beauty in the “wrong notes,” accidentals, and alterations that make music interesting. To compose and produce diatonically can leave the music bland. It will sound good, but it will be lacking that extra flavour that comes with chromatic notes, key modulations, and other forms of non-diatonicism.
So, I'd recommend thinking diatonically, but not necessarily following it strictly when composing.
So now that we know what the diatonic scale is and how we can use it in our own music, let's look at applying this thinking to other scales.
Expanding Our Thinking To Non-diatonic Scales
So far we've discussed functional harmony and modal harmony within the diatonic scale as well as going outside of the scale and adding in chromaticism.
We looked at the notes of the diatonic scale and the seventh chords they provide us with. By using these specific chords (and their extensions) and these specific notes, we can compose diatonically!
But what about the other scales that don't have the intervals of w-w-h-w-w-w-h? This is where we expand our thinking and use the diatonic idea in a non-diatonic fashion!
Let's look at some common scales that aren't diatonic
The Melodic Minor Scale
The Melodic Minor Scale is made of the intervals w-h-w-w-w-w-h. So it has equal amounts of whole tones and half tones as the diatonic scale, but they are ordered differently.
What chords does this scale create? Although they aren't truly part of functional harmony (much like they aren't diatonic), we can still harmonize the chords of the melodic minor scale to give a strict melodic minor sound.
We can definitely play modally in any of the melodic minor scale's modes as well. First, define a ‘pseudo-tonic' and then use the notes of its parent melodic minor scale.
An example of harmonizing the melodic minor scale and only playing the notes within can be found in my song Sum Triads from the album Fine Dining With An Octopus. Here is the main chord progression:
In the above example, the song is composed using only the C Melodic Minor, which is made up of C D E♭ F G A B.
The C and G are pedalled underneath (establishing the root and fifth for a modal sound) and the chords played on top are triads found within the scale (B'aug – B'dim – Adim – Fsus#4 – E♭aug – Dsus♭2 – Bdim – Baug -repeat).
Although this was not written diatonically, it was written with the framework of only using notes from the parent scale.
The Harmonic Minor Scale
The Harmonic Minor Scale is far from diatonic since it is made of the intervals w-h-w-w-h-wh-h. That whole+half tone really gives the scale its flavour, but also makes it a bit trickier to harmonize. What chords can you build using only the notes of this scale?
The Harmonic Major Scale
The Harmonic Major Scale is far from diatonic, as it is made of the intervals w-w-h-w-h-wh-h. That whole+half tone really gives the scale its flavour, but also makes it a bit trickier to harmonize. What chords can you build using only the notes of this scale? Although this is only one scale degree different from the Harmonic Minor scale, the harmonization will differ (just as the Major and Melodic Minor scales are different).
These are a few scales to expand our thinking of “composing diatonically” without using the diatonic scale. I believe that music theory is all about expanding ideas as much as possible. This is the big reason I added this “aside” when writing about composing diatonically, even though it isn't that by definition.
Perhaps I am way off, but originally I thought that playing diatonically meant to choose one scale and only use the notes of that scale. It isn't. It means to only use the notes of a specific major scale. However, I figured I'd share with you my thinking on the subject, and expand the discussion to non-diatonic scales.
I encourage you to write diatonically and with other scales. It can be rewarding to constrict yourself to only a certain pool of notes, even if they aren't from the diatonic scale. Try writing with exotic scales, too. This is certainly a topic I think about often when writing and composing and I'd love to hear what you think about it.
As always, thank you for reading and for your support!
Here is the song “Climbing With Escher” that I mentioned above in this article:
Here is the song “Sum Triads” that I mentioned above in this article: