Songwriting for Producers: Relating Bass Lines to Harmony

midi piano roll

midi piano roll

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In its simplest form, a bass part plays the root note of the harmony. This means that if the keyboard or guitar is playing a D major chord, the bass is playing D. If the chord changes to A major, the bass plays A, B minor the bass plays B, and so on.

You can hear an example of this sort of root motion bass in something like “On Melancholy Hill” by the band, Gorillaz.

Bass parts are often much more intricate. Because of our expectations to hear deep grounded bass notes, it can do a lot to make a track feel grounded or ungrounded. Emphasizing the root note of a chord typically feels like “home,” but when a bass part deviates, tension is created — there’s an almost elastic pull.

A quick example of this is something like Keane’s “Somewhere Only We Know.”

The bass starts off playing A, the root of the first chord, A major. Then in the second bar, the chord stays the same, but the bass plays a G♯! By playing the major seventh instead of the root, the bass creates some real tension and uncertainty about where we’re headed next.

In other styles, particularly dance music and funk, the bass typically emphasizes the root note on the downbeat, then is free to move melodically until the beginning of the next bar. This provides a lot of internal tension, yet these tracks tend to resolve on each downbeat before developing tension throughout the bar.

Let’s listen to Vulfpeck’s “Wait for the Moment” below.

The good news is, regardless of style, this gives you an obvious starting place. Play or write in some root note motion, and you’re on your way!

Altering Harmony

Bass can also change the interpretation of existing harmonies. For example, let’s say the chord of the moment is E♭ major.

If a bass part plays an E♭, it’s still E♭. However, if the bass plays a C, we’ll hear that chord more like a C minor seventh:

midi piano roll

This goes from being a single chord to becoming the progression E♭to Cm7.

There’s a great example of this in Bonobo’s “First Fires.”

At 1:36, the overarching harmony is a C minor seventh, and the bass moves from C, to A♭, to E♭ — creating three chords and some cool prosody with the lyrics as they say “fall!”

midi piano roll

How Does This Work?

Without a massive harmonic deep-dive, part of the theory behind this is that C is the relative minor of E♭. You can find out more about relative major and minor scales in our Theory for Producers course series, and in the premium course, Unlocking the Emotional Power of Chords.

Essentially, to find the relative minor of a major key, you go down three semitones. In the example below, if we’re in C major — go down three semitones and you’ll find A, the relative minor.

midi piano roll

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