This started as an email to Cory, on the heels of finishing Fight Songs bass lines.
One weird thing about writing and playing bass lines is that, the way my brain works, it feels like I’m searching for the ideal platonic form of the bass line for each song. It feels like there’s only one mathematically correct answer and I have to play around until I find it; which notes and rhythms, which octaves for the notes, where to put the runs, etc.
It’s not entirely literally true; I can hear some spots where two notes might be equally valid, but 99% of the time there’s an obvious right choice and it feels right and moral, even, to play it. That doesn’t at all mean the first note I try is right! Often the first 80% of the line will come to me pretty quickly, on my first few plays through the song, but I’ll spend a good amount of time on the last 20%, especially the ascending / descending runs, to make sure I hit the exact right notes. It feels like working out a proof, and it’s very satisfying to get right (and frustrating to get wrong)!
On one little line in “Lost,” the very end of the chorus that leads back down to the start of the chorus progression, I tried a ton of different combinations of notes for that 4-note descending run before I found the “right” one.
“Right” to my ear does not always mean technically perfect according to the notes in the chord or scale, either. There’s an element of my “voice” to the “right.” It’s not actually objective, of course, but it feels like working out something that is objectively correct (and more correct than the alternatives) more than “being creative” or “writing a bass line.”
I do not feel this way about any other instruments or sounds, only bass guitar.