I got invited to a jam this week and the keyboardist asked me if I know walking bass lines. I don't. So I turned to my book "The Bass Player Book" by Backbeat Books. In there on page 92 is a section on walking bass techniques. The first example is a four bar walking bass line over the chords C7-Em7-A7-Dm7-G7. The Em7 and the A7 are both in the second bar and have two beats each. Heres what I don't understand. The Em7 uses E-Bb. Thats a diminished note. The Bb is. I don't understand why that is used. Also for the A7 they use an A-Eb. That also is a diminished 5th. Can that work? I thought one would use the notes that make up the Em7 chord and the notes from the A7 chord. Help?