Mozart's piano needed a quarter of the force a modern key does
The instruments Haydn and Mozart wrote for were not quiet versions of today's concert grand. Fortepianos had leather hammers, thin strings, no iron frame and a range of around five octaves. On the Viennese type, a key took roughly a quarter of the force and half the travel of a modern one.
The story starts in Florence, where the harpsichord builder Bartolomeo Cristofori, working for the Medici, created the piano; an inventory of theirs records it in 1700. His clever action was only part of the achievement. Fitting hammers to a harpsichord would have sounded feeble, so he used thicker, tighter strings in pairs on a sturdier frame, and added a hand stop that made hammers strike fewer strings, an early soft pedal. Three of his instruments, from the 1720s, survive.
Spread was slow because the thing was expensive and hard to build. For a while pianos belonged to royalty in Portugal and Spain; Queen Maria Barbara, a pupil of Domenico Scarlatti, owned several, and the castrato Farinelli inherited one from her. A 1711 magazine article by Scipione Maffei, later translated into German, carried the design north, where Gottfried Silbermann began building pianos around 1730 with backing from Frederick the Great. Bach criticised his early efforts but seems to have approved of the improved ones he played in Berlin in 1747. Only in the 1760s did public performances and widely published fortepiano music appear.
Silbermann's pupil Johann Andreas Stein of Augsburg built the light, responsive Viennese action. He weathered his wood so harshly it cracked, then wedged the cracks, and the instruments lasted, as Mozart noticed. Stein's daughter Nannette Streicher carried on the business in Vienna with her husband; they were friends of Beethoven, whose last works need about six and a half octaves.
The sound differs from a modern grand. It is softer and fades faster, buzzes slightly in the bass, tinkles at the top and is rounder in the middle, and sudden accents stand out because they change colour as well as loudness. Through the 19th century the design grew into the modern grand and the older instrument dropped out of use, until interest in historically informed performance revived it in the later 20th century.
Source: Fortepiano
