I'm trying to rap my head around the tune "June 9th" by Boards of Canada.
So I started here:
and attempted to work out the chords that work with the bass line. My guess was Bbsus4, Bsus2, F#, G#sus4. This would suggest the scale of F# Major, however this tune doesn't sound Major. Therefore since the first chord is the third note of the the scale I presumed that the tune belonged to the Bb Phrygian mode. I tried droning a Bb behind the bass line and I actually think that Eb sounds better. Maybe the mode is that of Eb Aeolian... what do you think?
Then if we look at the first melody that sits on the base line, this starts here:
I tried playing this melody with my chords and I ended up changing the second chord to Bsus4 instead. I now have the scale F# plus the note E so things are no longer diatonic. Not only that but the melody also contains the note A.
I then tried my chords with both this melody and the second melody, which play together here:
This time I felt the chords were perhaps: Bbm, Bsus2, F#sus2 (or F#), G#m. The second melody also introduced the note D so things are really chromatic now.
What I'm primarily interested in is how a tune like this is composed. My guess is that the four bass notes were chosen first, then the four notes: D#, C#, B, G#, giving the notes from the scale of F#. But had I then tried to compose the two melodies that sit on top of the bass line, I would have restricted myself to notes in the scale of F#. What mechanism allowed the composer to choose notes outside of this scale and still have melodies that work perfectly with the bass line?