The chord progression is AMaj7/CMaj7/BMaj7/DMaj7. These chords are not linked to a common key centre so four different scales need to be played over them.
The good news is that it is the same scale that can be used each time. The Lydian mode works beautifully over unrelated major seventh chords and that's the focus of the chord progression.
Bass Solo Tricks
Bass players often find solos tricky as they're used to targeting root notes in bass line situations. That's absolutely the right approach and one that will serve you well in so many situations. When soloing however, avoiding the root is a good way to sound more musical.
Here's a cool trick over this progression:
- Over AMaj7 play A Lydian
- Over CMaj7 play A Dorian (which contains the same notes as C Lydian)
- Over BMaj7 play B Lydian
- Over DMaj7 play B Dorian (which contains the same notes as D Lydian)
AMaj7 to CMaj7 is a minor third and so is BMaj7 to DMaj7. Using the above approach means you can vastly simplify a potentially tricky chord progression. Just play the SAME things one tone apart (start on A for the first two chords, go up a tone and start on B for the next two chords).
This kind of playing makes things easier for you and avoids that constant temptation to jump back to the root note.
Things To Practise
Here are some things to make your solos sound better:
- Check out this lesson: 11 Ideas To Improvise INCREDIBLE Bass Solos.
Use the backing track to play along to.