(Notes that sound good) + (head-bobbing-inducing rhythms) = an amazing bass line.
I just made that up but it is the essence of what makes a world class bass line. Within that idea lies a few essentials that you need to know, including:
- The key of the song
- The chord tones of the individual chords in the progression
- The scale(s) that 'fit'
- What rhythms will work
This lesson will teach you all those things and I promise you'll be making great bass lines up with what you will learn.
Scroll down for the free backing track and PDF.
What Notes Fit?
The chords for this are:
Em/G/D/C
They belong to the key of E Natural Minor/G Major (they're 'relative' and so contain the same notes).
You need to know the E Natural Minor and G Major scales.
The resulting pentatonic scales are the bass player's secret weapon. Learn those and you'll be making up all kinds of bass lines before long.

How Do I Create A Great Sounding Bass Line??
It comes down to selecting the right notes (from the chord tones and the key) and then playing them with impeccable timing. Simplify things. That really does - nine times out of ten - provide the best path.
Practice these ideas over the backing track (115BPM).
Here's a PDF with the pentatonic shape and some tips. Have fun and remember my soon-to-be-patented formula:
(Notes that sound good) + (head-bobbing-inducing rhythms) = an amazing bass line.