The soundboard lies at the heart of a Steinway grand or upright piano, which is why great care is needed both in its design and in the selection of the wood. To meet the highest quality standards, only superior Sitka spruce with a regular grain and prescribed minimum number of annual growth rings is acceptable. The production of the Steinway Diaphragmatic Soundboard is based on a 1936 patent to achieve optimum performance in dynamic range and maximum sustain. Under this patent, the soundboard is gradually tapered from the centre to the edge, permitting freedom of movement and creating a sound of unparalleled richness, sonority, and sustain.
Created like the soundboard of violins to give a free and even response throughout the entire scale, the Steinway Model D soundboard is 9 mm thick in the centre and tapers to 6 mm as it approaches the rim and outer case before being double crowned. The design permits complete freedom of movement while displacing a greater amount of air, creating a richer and more lasting tonal response. Close-grained, quarter-sawn Sitka spruce — which has unusual stability and vibrance under stress and vibration — is used exclusively for the soundboard.
The better the materials, the better the sound. Steinway & Sons construct its soundboard bridges exclusively from vertically laminated hardwood with a horizontal grain, capped with solid maple. Each bridge is notched by hand for precise, individual string-bearing. This design ensures optimal sound transmission from the strings to the soundboard, resulting in a sustained, resonant tone—creating the inimitable Steinway Sound. In 1963, Steinway introduced the Hexagrip Pinblock, which is engineered to enable pianos to hold their tuning longer and with incredible precision.
The Hexagrip patented design features 7 laminations of quartered Hardrock maple stock. The grain is symmetrically distributed at successive angles of 45º and 90º, employing uniform grain direction around the circumference of the tuning pin to provide ultimate pin gripping. The exclusive design provides the tuning pin with smoother movement under torque, a more uniform retaining action, and a piano that holds its tuning longer.
Treble bridges are hard rock maple vertical laminations capped with solid hard rock maple; they are planed, graphite coated, drilled and notched by hand for precise individual string bearing, with a design that defies splitting. Bass bridges are continuous with treble and maple doweled.
Up to 20 tons of string tension is being exerted within a piano at all times. It is the function of the cast iron plate to accommodate this extraordinary force and provide strength and stability throughout the life of the piano. Steinway & Sons uses its own “bell-quality” casting to support this string tension and reduce vibration, which in turn enhances the sound. This component is so integral to the construction of a Steinway piano that Steinway & Sons owns and operates its own foundry, which produces cast iron plates to its exacting specifications. The plate is sturdy grey iron; filled, CNC–milled, and sealed; bronzed and lacquered.