This little guitar part packs a big punch when it comes to being able to use it in many other applications and keys. But the main reason for showing it here in A is to illustrate its versatility in that key, which allows us the open A to alternate with.
Travis picking usually has an alternating bass that is often two octaves of the same note, and this little “half barre” allows us to “slide” up to the seventh fret on the D string, creating one A, while we can now alternate with that A with our open A string, just adjacent to it.
The small barre position I am referring to is really just four of the six notes we would normally play as a complete 6-string E-form barre chord, only now the barre consists of only the top 2 strings, played by the index finger on the fifth fret. Many folks would refer to this as an “F” chord shape, which I guess is true, because that is what it repeats, but I already happen to think of the open F position as a partial E form barre at the 1st fret! But, if thinking of it as an F makes it more familiar to you, then so be it!
Please take care to work out the melodic part that exists over the bass part in a nice clean, rhythmic way. It’ll take some time, but will be well worth it. Enjoy!—Arlen Roth