An Easy Introduction to Playing Thumb-Driven Monotonic Bass Lines on Guitar

If you’re not sure what a monotonic bass line is, let alone how to use it, this guitar lesson is for you. You’ll learn to play one monotonic bass line, then apply it separately to three chords in the basic 12-bar blues progression, before plugging these patterns into the full form.

Play the Dead Thumb

To play monotonic, or dead thumb, bass lines, the idea is that a low string is used directly on all four beats in each measure, often sticking to the root note—that’s what makes them monotonous. So in an E7 measure, the bass line would be played as four consecutive quarter notes per measure on the low E string (Example 1). This sort of approach is best played with palm-muting—the heel of your picking hand muffles the string(s) just slightly, such that the sound is dampened, but you can still hear the pitches. You want to avoid ringing in the bass register, which can add an unwanted clutter to the sound. Palm-muting the monotonic bass line also gives it a nice textural contrast to the melodies that you’ll add with your fingers.

Add Melodies, One Chord at a Time

Start with the I chord (E7) in a 12-bar blues in E major. Example 2 shows a move with bluesy slides. Play the fretted notes on strings 3 and 4 with your second finger and the third-fret D on string 2 with your first. Use your index and middle fingers to pick the melody notes. Practice this figure slowly at first, while you get the hang of where the pinches fall, only gradually increasing the tempo.

In the second measure, note the trill—a rapid alternation between two notes, in this case, the open D and the second-fret E, played on guitar as a series of hammer-ons/pull-offs. If you are new to trills, work on this technique at a slow pace as well, making sure that you are playing the notes smoothly in consistent rhythm; if things feel too difficult, just eliminate the trills and play only the second-fret E on string 4.

The next step is to work on the IV chord (A7) measures, as demonstrated in Example 3.Play the third-fret G with your third finger and the second-fret C# with your second. Note the use of bluesy bends on string 1, as indicated by the curved line and 1/4 symbol. In these instances, nudge the string just a little toward the ceiling, so that its pitch is slightly raised. Subtlety is key here; be sure not to overdo it.

After you’re comfortable with Exs. 2 and 3, try Example 4, which takes a similar approach to the V chord (B7), using your second finger to play the second-fret B on string 5 and your fourth for the third-fret D above. If you’re not accustomed to fretting notes with your littlest finger, it might feel strange at first, but it’s definitely worth the effort to get this useful digit in shape. Note that the last two beats of the second measure include a descending melodic line that sets up a nice return to the I chord.

Play Through the 12-Bar Form

Once you have learned the first three examples, you will be ready to stitch them together to play the full 12-bar blues form (Example 5). If you get bored of playing it the same way, try some cool variations: For the A7 chord, as depicted in Example 6, you can throw in a low-G bass note (bar 1, beat 4.5) to add rhythmic drive. And rather than just sit on the B7 chord for two measures in bars 9–10, you can play one bar of B7 followed by one of A7—see Example 7.

If you’ve mastered this lesson, with its focus on monotonic bass lines, then not only do you have a fun little blues study under your belt, you’ve also got the tools to play a solo on the 12-bar blues in E whenever the opportunity arises.