The piano soundboard can have several possible defects or imperfections. Piano owners are always interested in how far or if these phenomenon’s influence the piano´s performance.

Wavy or wrinkled soundboard:
If the piano is placed in space with increased air humidity its soundboard can be slightly wavy or have little bumps along the grain of the sound board. This deformation is a regular feature of the soundboard. The soundboard is crowned, glued to the wooden frame around its periphery, loaded by the strings from above. It has no chance to increase its crown upon increased humidity while swelling. So it crinkles, forms compression ridges, and compressed itself a little. This compression appears along the grain or glued joints in the soundboard. These symptoms have only aesthetic importance and they don´t affect acoustic properties of the pianos, they are not a defect of the soundboard. Quite the opposite these symptoms are the signs that the soundboard was well moisture conditioned to the low moisture content before its assembly to the piano. Such soundboard is able to resist very low air humidity and there is minimal risk of cracking.

Cracked soundboard:
The cracks in the soundboard can develop in consequence of very low air humidity and low wood moisture content (tension cracks) or on the contrary in consequence of very high humidity (compressive and shearing cracks).

The cracks in themselves have no influence on the acoustic properties of the piano, they don´t reduce its acoustic output or change the tone color. Simplified it can be said if the ribs and bridges are well glued the soundboard keeps its shape and none of its part generates any unwanted noise, then the cracks have no negative influence on soundboard function. But usually big soundboard cracks are repaired for aesthetic reasons.

Unglued ribs or bridges:
Ribs that have released from the soundboard decrease rigidity of the soundboard’s crown. They can effect deformation of the soundboard and loss of the down bearing. This can be the reason of noises or change of the tone color or decreasing of acoustic output of the piano.

Unglued or cracked bridge or loose bridge pins are also serious problems that decrease the acoustic output of an instrument and they can be a source of noises.