What Is a Bass Line?
Now that you understand the roles of each instrument in the rhythm section, it's time to bring the focus back to knowing more precisely what you will be doing. You have to play your part, but what is it?
If you are covering a song, you simply have to learn the part on the record or read some sort of provided notation. However, if you are in a more creative ensemble, where original compositions are being developed, you might have to create your own part.
If you will be simply performing a bass line that has already been recorded or composed, there are certain standards that you should consider. Do you want to play the bass part note for note as written, or do you want to take some liberties and add some improvisation? This decision is almost always dictated by the genre of music you will be performing.
If you are playing jazz or blues, you are usually expected to take chord changes or partially written notes and turn them into a more compelling part based on improvisation. Conversely, if you find yourself playing music that is more akin to classical music, you may need to stick more closely to the written score. Rock and its subgenres often have a broader range of performance expectations depending on which subgenre you are playing. For example, if you are playing Rush cover tunes, you probably will be expected to play the bass lines exactly as written. However, if you're in a jam band, you're obviously supposed to jam, meaning to improvise prodigiously.
There are often greater musical challenges if you are lucky enough to play in an original band. If you are allowed to create your own bass lines, it may be quite a challenge at first. So where do you begin?
You have to have the smarts to really understand just what kind of ensemble you are playing in and what kind of expectations the other musicians have. At the same time, you need to please yourself too. In general, bassists must play with empathy and generosity, and they have to enjoy backing up singers and soloists. Yes, bassists are featured on certain selections, and yes, select bassists consistently grab the spotlight. But usually the singer takes top billing in a rock or pop setting.
After you've thought about what it is you need to do stylistically, get some nuts and bolts information about the song. You'll need to determine what key or keys you'll be playing in, what the chords in the tune are, and what the rhythmic groove is. Subsequently, you'll fill the void with elements like root notes, other chord tones, scales, and arpeggios. As you work your way through this book, you will learn more and more about how to build appropriate bass lines.