The vibration of a piano’s strings alone would be too quiet to be heard; their sound must be amplified. Piano strings, like those of a violin or a guitar, press down on a bridge which conducts their vibration to the large, thin piece of wood called the soundboard. Wooden ribs glued across the board, underneath, help spread the strings’ vibration throughout its mass.
While a crack in a violin body is a very serious matter, a crack in a piano’s soundboard can be repaired easily, without losing any of the piano’s tone quality. Maintaining proper humidity during the winter heating season helps to prevent cracks from occurring.
The sound board is a five eighths inch thick wooden board in the back of the piano. On the back of it, it has one inch ribs which stabilize it by running against the grain of the sound board.
The traditional sound board is made of several five eighths thick boards which are glued side by side across the whole inside of the piano. It is the best sounding board, but with age, it can crack.
Our Sitka Spruce and Canadian Spruce soundboards are glued down to the perimeter of the piano case and bellied like a diaphragm in the center to best amplify the tone of the struck piano strings.
The soundboard is not flat as it appears. but has a crown held in place by a series of ribs. If the soundboard were flat or if it were to lose this crown, there would be very little volume or tone. The ribs are made of a lightweight wood such as sugar pine, are double notched and fitted into soundboard lining. They are tapered to fit and correspond with the taper of the soundboard.
The soundboard in an upright piano often has its properties diminished since it is frequently situated against a wall and enclosed in its case. Conversely, the soundboard of the horizontal grand has the advantage of open space between the bottom of its case and the floor as well as its opened top resulting in a clearer more present sound.