Watch the Roots On The Downbeats online guitar lesson by John Goldsby from Upright Bass Handbook
This line might seem simple at first glance, but we're using many of the key elements needed to play the double bass in time and in tune. Remember to keep your left wrist straight and use the weight of your left arm to help anchor the string to the fingerboard.
I've written in the left hand finger that you use to play each note, and the string where you find the note. All of the notes in this exercise are in half position; the very lowest position on the bass. With your right hand, strike through the string with a circular motion, and let the note ring for four beats before you attack the next note. It's important to hold the note with your left hand for four beats, and shift exactly at the last possible millisecond before you play the next note.
Holding notes like this is a bit harder on the double bass than on the electric bass, but once you learn to harness the weight of your arms, you'll be able to play through the exercise in time with a big, fat bass sound. This exercise lays the groundwork for playing walking basslines, four beats to the bar.