Abstract: A piano construction providing significantly improved tonal quality and balance by utilizing a soundboard which is tightly coupled to the string frame along the top edge and the two side edges of the soundboard except for a loose coupling adjacent the end of the bridge in the treble section along one of the side edges and which soundboard is loosely coupled along the lower edge as the latter is normally positioned in an upright piano. Additionally, a massive support rib on the string frame adjacently extends along the top edge of the soundboard to improve tone, and the strings at their upper ends are held in V-notches at tangential points about the string circumference to avoid lateral vibration. The string frame and soundboard are designed to produce a partially free diaphragmatic-type operation free of soundboard dead spots which maximizes tonal qualities for the dimensional restrictions of small pianos.