Chords and modal interchange

One of the most powerful music theory concepts you can learn is how to make chords from scales. If you learn a few scales, then you get a whole bunch of chords for free. The specifics of all the chord names can be complicated and daunting. But the concept of constructing them is very simple. Take a seven-note scale, like, for example, C major.

Start on any note. That’s your chord root. Go around the scale clockwise, skipping the next scale degree to land on the following one. That’s your third. Go around clockwise and skip the next scale degree to land on the following one. That’s your fifth. Do the same thing to find the seventh. (You can also keep going to get the ninth, the eleventh, and the thirteenth. Then you will have used all the notes in the scale.) Any seven note scale will produce seven different chords, and they will all sound good together in any order and any combination.

Below I present the seventh chords you can produce by systematically working your way around an assortment of widely used scales and modes: the major scale, Mixolydian mode, Lydian mode, Lydian dominant mode, Phrygian dominant mode, the natural minor scale, Dorian mode, the harmonic minor scale, the melodic minor scale, Phrygian mode, and Locrian mode.

Noteflight’s output is not very musical. Here’s the same information with a groove:

This is not all the chords that exist! But it is a wide assortment of interesting and useful ones. Here, I explain what all the chord symbols in the chart mean. They are not as horrible as they look!

Major chords (four semitones between the root and third)

• C7 – C, E, G, B-flat. Say it: C seven. Classical musicians sometimes call this a major minor seventh chord, which, why.
• Cmaj7 – C, E, G, B. Say it: C major seventh. A sophisticated sound.
• Cmaj7(#5) – C, E, G-sharp, B. Say it: C major seven sharp five. A strange chord you do not use very much outside of modern jazz.

Minor chords (three semitones between the root and third)

• Cm7 – C, E-flat, G, B-flat. Say it: C minor seven. It’s smooth.
• Cm(maj7) – C, E-flat, G, B. Say it: C minor (major seven). A very dark, weird and mysterious chord much loved by modern jazz musicians.
• C°7 – C, E-flat, G-flat, B-flat-flat (so, A). Say it: C diminished seven. A symmetrical stack of minor thirds. A film score cliche for darkness and drama.
• Cø7 – C, E-flat, G-flat, B-flat. Say it: C half-diminished seven. This name is awful! Here’s the logic. The fully diminished seventh chord has a flat fifth and a diminished (doubly-flatted) seventh. The half-diminished chord has a flat fifth but a regular flatted (non-diminished) seventh. Jazz musicians sometimes call this chord Cm7b5 (C minor seven flat five) because it’s the same as Cm7 but with a flat fifth, which is a more complicated chord symbol but nicer conceptually.

So what can you do with this information? The main thing is: write songs. The chords you generate from a given scale will all sound good together, in any order and any combination. That’s always a safe place to start. However, you get more colorful and unpredictable results by mixing chords from different scales together.

For example, let’s start with the chords you get from C major: Cmaj7, Dm7, Em7, Fmaj7, G7, Am7, and Bø7. They all sound… fine. Perfectly nice. But definitely lacking in drama. So let’s replace some of them!

• If you replace Cmaj7 with C7 from Mixolydian and Fmaj7 with F7 from Dorian, you get the characteristic sound of the blues.
• If you replace G7 with Gm7 from Mixolydian, you get a really nice modal rock sound.
• Bø7 is something you really only hear in classical music. Replace it with Bbmaj7 from Mixolydian for a smooth classic rock sound, or Bb7 from natural minor for an edgier, more tragic sound.
• Replace Fmaj7 with Fm7 from natural minor for extra pathos.
• Replace Am7 with Abmaj7 from natural minor for an epic film score cliche. Bring in Ebmaj7 for a similar effect.
• Replace Dm7 with Dbmaj7 from Phrygian for a Middle Eastern sound.

The possibilities are endless! Bear in mind that you can leave the sevenths off of any of these chords too.

Knowing what scale produces what chord is also useful, because then you know what notes are available to you for melody writing or improvisation. If you are in C and you see Cmaj7, Dm7, Em7, Fmaj7, G7, Am7 and/or Bø7, the C major scale will work over all those chords. If you see C7 or Gm7, use C Mixolydian. If you see F7, use C Dorian. If you see Fm7, use C natural minor. And so on.

This is not a complete explanation of all of Western harmony. Even within these groups of chords, there are many rules, norms and guidelines about which chords go together. Before you start learning all of it formally, I recommend that you start trying different combinations out by ear and see what you discover. Once you have an intuitive understanding of how chords fit together, the formal explanations will make a lot more sense.