I have a melody for a 90bpm pop song that I wrote but am struggling with the bass line pattern a little bit. It is not what notes to play but what pattern I should use that I am stuck with. I don't have any other instruments except that I know what chords I want to use. The problem is that the melody changes a lot and doesn't have a set pattern so my question is, when you have a complex ever-changing melody hitting a lot of 16th notes and "in between the beats" is it better to keep the bassline simple and on the 8th note divisions of the grid so as to not confuse the two? Most songs have some kind of melody pattern in the lead vocal which is fine but I like only doing that in the chorus and leaving the verses more diverse so the bass pattern is always tough for me because using any 16th notes in my bass pattern (which should remain more or less the same in the verse) always conflicts with some part of the melody. Can anyone give me a hand or tips please?
For me personally I'd stick with 8th notes, and put a lot of root notes in it. I've found that the average listener will only focus on a bassline if there isn't any vocals to distract them! (Or if it sounds wrong!) Our singer is amazing so she'll carry the song and I'll only add bass flourishes at the end of the phase when she not singing or holding a note.
It's all personal preference I guess, but that's my two-penneth.
The bass pattern depends on the type of song too. If one is writing for a particular type of dance (tango, foxtrot, waltz, rumba, mambo, samba, etc.) the bass line may be written to emphasize the rhythm of the dance. Of course, the individual notes depend on the melodic and harmonic goings on in the music.
The bass is fundamental to making the melody sound good; it should support the melody. In most popular music, the bass shouldn't dominate, especially where the vocalist is being featured. The bass may move around a bit between sections though, to make the listeners aware that something is happening.
The bass should generally stick to chord roots at cadences and other important places within the song. It can move between these to keep the overall impression of activity.