In music, alternate bass is a performance technique on many instruments where the bass alternates between two notes, most often the root and the fifth of a triad or chord.
On the guitar and bass guitar this is accomplished with the right hand alternating between two or more strings, often the bottom two on the guitar. In the following example in the C major chord C is located on the fifth string while G is located on the adjacent sixth (lowest) string and in the F major chord F is located on the adjacent fourth string:
On a Stradella bass system accordion this is accomplished on the left-hand manual on bass-note buttons which are arranged according to the circle of fifths with the counterbass displaced by a major third, placing the bass button for the fifth directly above and counterbass button for the fifth three below the bass button for the root.