The Diaphragmatic Soundboard: The Heart of the Steinway Tone, Color and Richness

Steinway Soundboard Craftsmen

More than 98% of performing pianists insist on using a Steinway piano. Why this dramatic vote of confidence? The sound of the Steinway piano is one of power, warmth, richness and color - the result of many exclusive features, including the Diaphragmatic Soundboard. Over 70 years ago, Steinway patented its “soundboard for pianos,” continuing its tradition of superior craftsmanship, innovation and sound.

1937 Steinway Soundboard PamphletClick for a larger version of the original Steinway pamphlet from 1937 describing the diaphragmatic soundboard.

The Patented Steinway
Diaphragmatic Soundboard

1) Patented Design

The Steinway Diaphragmatic Soundboard was designed and patented to act like a true diaphragm. The greatest thickness is in the middle, from which point there is continual tapering in all directions toward the outer edges. This design reduces the energy needed by the soundboard to vibrate, an efficiency that permits a greater variance of tone, color, and richness.
The Steinway’s rich tone is due also to the full (front and rear) duplex scale design. The design allows for the fretted “non-speaking” lengths of the steel strings to vibrate in sympathy with other notes being played. This feature would contribute little, though, if the soundboard were not sensitive and efficient enough to respond to subtlety. Without the Diaphragmatic Soundboard, the tonal attributes created by the duplex scale design would be like words whispered to someone with earplugs.

Steinway Soundboard Patent 1973 Fig. 3“Original illustration from the patent of Feb. 9, 1937.” Read the Full Article (2.7 MB)

2) Superior Materials

The materials used in the manufacturing of the piano are just as important as the design. Steinway pianos combine the resonance of Sitka spruce with the rigidity of hard rock maple to intensify the richness of the sound.
All Steinway soundboards are made with Sitka spruce, the most resonant wood available. Soundboards in Steinway pianos are constructed from solid (never laminated) Sitka spruce with annual growth rings measuring 8-12 per inch. These close-grained lines enable the sound-producing energy to travel to the end of the board, which is custom-fit to the top of the inner rim. The energy travels more efficiently when the soundboard is close-grained.
This is just the beginning. When the sound-producing energy reaches the inside of the single-bent rim, it instantly returns to the body of the soundboard, where it resonates. The efficiency of this process is much enhanced by the hardness of the rim, which is constructed from hard rock maple.

Steinway Soundboard Patent 1973 Fig. 6“Original illustration from the patent of Feb. 9, 1937.” Read the Full Article (2.7 MB)

3) The Quality of Steinway

The design, shape and materials of the Steinway soundboard make it the best found in any piano. Each Steinway soundboard is custom-made, by hand, to fit to a specific piano. This perfect fit means there is no wasted energy.
There are more than 250 skilled craftspeople at the Steinway New York factory, yet it takes almost an entire year to craft a Steinway piano; the soundboard itself requires 7 days in a specialized conditioning room before installation – which is performed by a skilled artisan called a “bellyman” over the course of a full day. Integrity of design, materials and workmanship is maintained in the creation of all Steinways. Each aspect of this threefold foundation plays a role in the instrument’s superior tone.

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