Accordion/Introducing the Piano Accordion

Unlike the button accordion, which has buttons on both sides of the instrument, the piano accordion has a piano-style keyboard for the right hand and buttons for the left hand. The buttons include bass notes and chord buttons. The least expensive piano accordions may only have major and minor chords. One level up is to have major, minor and dominant seventh chords. A professional piano accordion has major, minor, dominant seventh, and diminished chord buttons.

Introducing the Piano Accordion
This module currently draws heavily on text from the Wikipedia Accordion article.

The piano accordion is the instrument most often indicated by the term "accordion", but it is one of the most recent inventions among accordion types, appearing late in the 19th century and not accepted worldwide until the early 20th century. It has a right-hand keyboard similar to a piano. This is great news for you if you ever took piano lessons!

The left hand keyboard is usually configured in the Stradella system, a combination of chords and single notes, arranged in a uniform series by harmonic relationship. This is the system we'll be focusing on throughout this book.

Occasionally, a free bass left hand is used, which has a series of single buttons in an arrangement similar to the chromatic button accordion. The free bass system facilitates the playing of bass melodies and counterpoint over a melodic span greater than one octave. It also allows for chord inversion and invention of chords not present in the Stradella system, although the Stradella system also allows creation of extra chords and inversions using simultaneous multiple chord buttons.

Converter bass systems allow an instrument to be readily converted from a Stradella system to a free-bass system with a switch.