Although playing open-string bass runs was not unusual for dance band guitarists of the time, Shamblin used his knowledge of jazz and large-ensemble arranging to harmonize his bass lines with a series of mostly close-voiced chord forms. The example below is a typical Shamblin-style arrangement that can be used on a “San Antonio Rose”-type (I-IV-II-V-I) progression.
In measures 1 and 2, we see how Sheldon creates a descending bass line starting with a D chord, moving through two inversions of D7 (D/C and D7/A). At measure 3, alternating bass is used on the G barre chord. Descending to the 7, D, of E7 (E7/D) sets us up nicely for a half-step bass drop into A9/C#. Measure 5 features a slick maneuver where Em/B shifts smoothly into the A dominant harmonies in the next bar, which resolve, finally, back to D major in bar 7. On the second pass, we see a variation used: Measures 9-11 start with a first-inversion D chord and descend down to bar 11’s G/B, using bar 9’s Am/E as a passing chord.
Keith Baumann is a professional musician and guitar instructor in the Chicago area. He is currently working on a Western swing guitar book and can be reached via email at firstname.lastname@example.org