Here is another practice track for the bass players. It is an E 12 Bar blues. The rhythm part is played with all dominant 7th chords, while the lead guitar plays with the E minor pentatonic scale. Here are the chords:-
|E7 | | | |
|A7 | |E7 | |
|B7 |A7 |E7 |E7 |
Try constructing bass lines from your dominant 7th chord arpeggios. Add in the 6th for a classic blues bass line. For your runs, try the the myxolydian mode from the root of each chord.