More bass lines

When the Major 3rd (3 draw B) of the I7 Chord is omitted and the Flat-7th (5 draw F) is used in place of the Major 6th (5+ E) you get a very bluesy sounding bass line. Here are some examples (again, play in the shuffle rhythm).

Ascending Box
2 2 4 4 5 5 6+ 6+
R R 5th 5th Flat-7th Flat-7th R R

Descending Box
2 2 6+ 6+ 5 5 4 4
R R R R Flat-7th Flat-7th 5th 5th

Of course it's important to learn the IV7 and V7 equivalents to any bass line. Here's the Descending Box...

IV7 = 1+ 1+ 4+ 4+ 3' 3' 2 2

V7 = 1 1 4 4 4+ 4+ 3" 3"