Just looking at a polychord can make your brain scramble for a second. Two chords at once? It can take a bit of getting used to.
But there’s no reason to be afraid of polychords, it’s actually simple enough once you break it down.
Plus, using polychords in place of chord extensions can help you stay creative, and keep things simple.
If you play the guitar or piano, knowing polychords will open up another world of extended harmony on your instrument.
Let’s get right into what polychords are, and how to use them effectively.
What are polychords?
A polychord is a type of chord that contains two chords that exist one on top of the other.
They function similarly to slash chords. Instead of one note in the bass voice, you’ll have a whole triad or seventh chord. The only difference in notation is that instead of a slash, there is a horizontal line that splits up the chords.
Polychords are another way to express upper extensions, and altered harmonies.
For example, take the F major chord. It has the notes F, A, and C. Now think of the G major chord with the notes G, B, and D. This will traditionally give you an F major 9 #11 13 chord, but it can also be written as simple as G over F.
It’s another way to look at complex harmonic structures to see their component parts.
When notating polychords, the chord played in the upper voices will be found on top, with the other chord in the lower voices at the bottom.
Now that you know how polychords are built, let’s dig into how you can organize them and use them in your music.
How to navigate polychords
The best way to start experimenting with polychords is to use the circle of fifths. Choose a base chord that’ll live in the lower voice, and use the rest of the circle of fifths for the upper voices. The further away you get from the home key, the darker sounding it will get.
For example, G over C is close to the key of C major and shares many common notes. You’ll get notes that live in the scale of both C and G major—which are closely related keys.
Moving further away from C, you’ll come across chords that sound much darker and ‘out there’. Take for instance, B over C. You have B D# and F# which are 7, #9, and #11 in the key of C major.
It’s important to note that other chord qualities can be used other than major. It’s not uncommon to have a seventh chord in the lower half, with a triad on top.
Many polychords exist as a single chord that can be notated with extensions, but there are some combinations that have polytonality. This means that there is more than one tonality or scale that’ll sound correct when played over top.
In some cases, it’s easier to say that a song has multiple key centers based on the chords in its progression.
As a single chord
If you have trouble using upper extensions in your chords, experimenting with polychords is a perfect way to start. Set your base chord and choose another chord that exists close to the key in the circle of fifths.
Slowly move away from the home key and venture into unknown territory. Start noticing the difference between the chords.
For example, a C Lydian chord with all its extensions is just made up of a C major seventh chord with a D major triad stacked on top! Knowing this shortcut is sometimes easier than spelling out each extension or remembering the mode.
Polytonality starts happening when you use different chord qualities such as diminished, augmented, and begin moving further away from the home key.
For example a polychord containing a D7 chord with the notes D, F#, A, and C paired with an E major triad with the notes E, G#, and B have tonalities of G major and E major at the same time.
Some songs aren’t easy to explain with conventional music theory. In these situations a single key signature or mode isn’t enough to make sense of them.
In some cases, it’s easier to say that a song has multiple key centers based on the chords in its progression. Don’t worry too much if you find yourself in this territory while writing or improvising—if it sounds good, it is good!
So many chords
Polychords sound like confusing advanced music theory, but they’re really just another way to describe concepts you already know.
Whether you struggle with building chords or adding extensions, understanding polychords gives you yet another tool to create harmonic interest in your chords and progressions.