The role of the bass in a song is to bridge the gap between the drums and the gutiar. To do this, we combine the chord progression of the guitar line with the beat of the drums. Once establishing the key of the song, the tempo and the chord progression, here are a few tricks I like to use to write my bass lines.
1. Lock in the with the drummer
- Pick a drum and try playing the roots to the beat that he is using. Experiment. A lot of bassists like to use the kick drum, but the hi hat, ride and snare can also provide some interesting alternatives
2. Lock in with the guitar
- Another technique is to copy the rhythm of the guitar whilst ignoring the drum beat all together.
3. Play something melodically and rhythmically different from the guitar and drums
- This is where you use your knowledge of the key and your modes (You DO know these, right?) and craft a bassline that adds a melodic counter point to the song. This is something that can usually be defined as a hook or counter melody to the vocal line. ex. Duff McKagan's bass intro to Sweet Child of Mine.