How to Write a Chord Progression for a Blues Scale Bass Line

Jared from the States emailed us with this question: “I used the blues scale to make a bass synth line. I really love it, but I can’t seem to add chords to it. I’m getting REALLY frustrated!!!! Can you please show me how I can add a chord progression? I’m using the A blues scale.” Thank you, Jared. I’m so sorry you’re feeling frustrated, that really sux! If it’s any consolation though, this is a very common problem with a very simple solution. And on that note, here’s my one-sentence answer:

As you mentioned a synth, I’ll presume you’re working in an electronic genre and not the blues genre (as blues has its own rules), so, you simply use the natural minor scale from the same root to create a chord progression to your blues scale melody.

Let’s work through an example. You said your synth bass line is in the A blues scale, so that’s A C D E♭ E♮ G. Remember, the ♭5 (E♭) is merely a spicy decoration, so we don’t treat that as part of the harmony. And yes, that ♭5 (E♭) will clash with all the chords that contain the 5 (E), like the root triad (Am), but that dissonance is a big part of the blues scale’s charm.

Now, here’s the hack for writing a chord progression to a blues scale melody. Because we can ignore that decorative ♭5 (E♭), we’re left with the pentatonic minor scale, which is the natural minor scale (A B C D E F G) without its 2 (B) and ♭6 (F), so that’s: 1 ♭3 4 5 ♭7 (A C D E G). As all five notes of the blues scale, excluding that decorative ♭5, are in the natural minor scale, you can use the A natural minor scale to write a chord progression to your A blues scale melody. So in other words, your chord options for the A blues scale and the A natural minor scale are exactly the same. The chords are: Am, Bdim, Cmaj, Dm, Em, Fmaj, Gmaj.

For example, if you have a short synth riff that loops, it could be fun to play through one different chord under each loop of the riff. So, if your riff is: A → G → E → D → E → C → E♭, then we could play one chord for each loop.

Figure 1: Bass line in the A Blues scale

Something like this: Am → Cmaj/G → Gmaj → Dm/F → Fmaj → Fmaj/A, which brings us back around to our root chord (Am). Now let’s put that riff in the bass and play this chord progression over it. By the way, the notes in these chords have been re-arranged to flow smoothly into each other. For more on that technique, please watch our Chords (song 1) video.

Figure 2: Chord progression in A natural minor, which works over the bass line in A Blues scale

So that’s my answer! Thanks for watching. If you’d like to learn more about writing chord progressions in a natural minor scale, please read chapter 12 in our free book: 12 Music Theory Hacks to Learn Scales & Chords. Do you feel a little bit smarter now than you did a few minutes ago? Then subscribe so we can do it all again next week! And if you have a question you’d like us to answer here on Q&A Tuesday, please comment below or connect with us.

Kate Harmony
Music Teacher
Victoria BC, Canada