Grimes - “Oblivion”
What is this bass sound?
Synthesizers play all of the instrumental parts in this song. Besides the vocals, the bassline is the most prominent layer here.
How is this bassline put together?
The bassline is eight bars long, but can be further broken down into two groups of four bars.
The first two bars are a pattern made from the notes in a D minor triad. The two bar pattern repeats twice.
while the second four bars transpose the same pattern down to play the notes of a B minor triad. This is also a two bar pattern, repeated twice.
A rhythmic pattern of single notes that outlines a chord is called an arpeggio, and this is a common technique for creating basslines. Many synthesizers come with arpeggiators, which automatically create arpeggiated patterns when you hold down the notes of a chord.
Experiment with your own basslines that use arpeggios.