Bluegrass Bass Runs
After you’ve settled into the basic bluegrass and country boom-chuck rhythm pattern, you’re bound to start looking for something else to do with your fingers to help embellish different parts of a song. One easy way to do this is to add bass runs between chords.
Example 3 shows one of the most common bass runs in the key of G—a simple walkup to the C chord, using the first four notes of the G-major scale: G, A, B, C. If you use your middle finger for the B note, your hand will be in a good position for the C chord.
Example 4 shows a similar bass run, but this time from the G to the D chord. Notice that this run skips the first note of the scale, moving right to B and then C to get to the D note (the root of the D chord) at the beginning of the next measure.
When playing or inventing bass runs, make sure you know where you’re going and when you need to get there. For example, play the two G–D bass runs in Examples 5 and 6. In Example 5, the run starts on the second beat of the measure rather than the third, as in Example 4. The second beat is a perfectly good time to start, but you’ll notice that you have to add a note: instead of skipping the A note in the scale, you run right up the G scale to D: G, A, B, C, D.
Now imagine that you had this rhythmic idea in mind when you started your run, but instead of starting on A, you started on B. To get to the D chord at the right time, you might insert a C# note between C and D (Example 6). Otherwise you’d get to the D chord a beat early, potentially throwing off your rhythm and eliciting malevolent glares from your fellow band members.
Excerpted from Bluegrass Guitar Essentials