Soundboard — The Heart of the Piano
The ultimate goal of a piano soundboard is to maintain the full richness of the vibrations generated by the strings, gradually converting them into sound waves which are propagated efficiently through the surrounding air.
The soundboard is formed of planks 11 mm thick and with a width varying between 8 and 12 cm. These are glued edge to edge, forming a thin “diaphragm” that is very mobile and offers a large surface area.
Ribs are glued to the underside (flexible wooden strips shaped so that they are rigid at the centre and more flexible at the ends), perpendicular to the grain of the soundboard, giving them greater uniformity and a slight upward curvature.
Then, the mid-upper and bass bridges are glued in place, which transfer the vibrations from the strings to the soundboard.
The soundboard must react uniformly to the vibrations of the strings, absorbing energy gradually and converting it into sound.
A soundboard with too much mobility may create explosive notes in terms of attack, but they will have a short duration.
However, going too far the other way, restricting its mobility, will create a sound that is too weak. A perfect balance is required that allows the soundboard to amplify the vibrations from the strings whilst maintaining good duration (known as “sustain”) and also guaranteeing sufficient harmonic richness and power (when the pianist desires it). The soundboard must also guarantee sufficient strength to withstand the static vertical load exerted by the strings tensioned on the bridge, along with stability of form (e.g. curvature), reacting as little as possible to changes in humidity and temperature, allowing stable tuning of the piano.
Fazioli has dedicated a significant portion of its research to the optimization of the soundboard, and patenting innovative solutions for its creation.
The soundboard made with a special structure featuring three crossed layers of wood and a thickness of micrometres represents an important step towards achieving a solution with more uniform acoustic response and even greater stability over time, as well as under extreme environmental conditions (e.g. very dry or very humid environments).