Most accordions have a dedicated bass section for the left hand. There are two primary mechanical systems used to play these notes:
5 Different Accordion Bass Systems | All About The Accordion Bass Buttons Bass Accordions
High-end professional accordions often feature a "converter" switch that toggles the left-hand buttons between Stradella (chords) and Free Bass (melodies) modes. 2. Specialized "Bass Accordions" Most accordions have a dedicated bass section for
Typically include "Counter-bass" (major thirds), "Fundamental bass" (root notes), and then columns for Major, Minor, Dominant 7th, and Diminished chords . "Fundamental bass" (root notes)