High-grade, straight-grained, quarter-sawn spruce is used for the soundboard’s resonant qualities and high strength-to-mass ratio. The soundboard is solid and not laminated, which creates the best resonance and projection of sound. In 1936, Steinway patented the diaphragmatic soundboard, which was designed to be thicker in the middle and gently tapered to the edges. The Boston soundboard has tapered thickness from bass to treble. A thinner soundboard in the bass area vibrates more freely, resulting in a richer, fuller tone.
Boston backposts are massive — providing a solid foundation for the resonating soundboard and tensioned vibrating strings, thus helping create a beautiful tone. Boston backpost locations are staggered — located where the string tension is greatest, instead of neatly equidistant. Massive staggered backposts help provide superb tone and maximum stability, ensuring the piano will last, tunings will be more stable, and piano tone will be enhanced for the years and decades to come.