Piano soundboards are thin boards commonly made of spruce approximately 3/8″ thick glued together and extend from the bottom of the piano on a vertical, and tail of the piano on a grand, to the pin-block and then across the full width of the piano. The soundboard has a crown which is very important to the tone and resonance of the piano. The back of the soundboard has ribs made of wood that are glued to the soundboard to strengthen and support the crown. Wood for soundboards, usually spruce, needs to be light and elastic. The best results are obtained when the grain of the soundboard runs parallel to the bridges. The bridges are usually made from maple and their primary function is to transfer the string vibration to the soundboard. Older piano soundboards often form cracks especially where the thin boards are glued together. This is not detrimental or life ending for the piano. However, it can cause buzzing from certain frequencies. It can be repaired with re-gluing or even shimming. Soundboards that have several cracks, mostly due to age and/or large fluctuations in humidity over the life of the board, can loose crown which would result in a dull lifeless tone quality. If crown is lost, soundboard replacement maybe necessary to obtain good power and tone. It is best to have a used piano checked by a qualified piano technician to fully evaluate the piano soundboard and its condition.
// by Piano Emporium