Walter was born in Neuhausen auf den Fildern, Germany. The record of his marriage to a widow named Anna Elisabeth Schöffstoss in 1780 indicates that he had moved to Vienna by that time. His earlier surviving pianos are dated to this year. His piano business was evidently successful. In 1790 he was awarded the status of Imperial Royal Chamber Organ Builder and Instrument Maker. By 1800 he was employing about 20 workmen. In that year he was joined in the firm by his stepson Joseph Schöffstoss, and the pianos came to be labeled "Anton Walter und Sohn". The last surviving Walter piano is dated 1825, and he died the following year.
Walter's pianos
Walter's instruments are classified within the so-called "Viennese" school of piano design. This school originated with Johann Andreas Stein, who built pianos in Augsburg. In Viennese instruments, the head of the hammer is closer to the player than the hinge, and the hammer is made to rise when its short opposite end is caught on a hook. Like all early pianos, those of the Viennese school were of far lighter construction than modern instruments and had a quite distinct sound; for general discussion, see fortepiano. Walter improved on Stein's design by adding to the action a back check, which caught the hammer on its descent, preventing it from bouncing up and down in lively playing. This innovation was generally adopted by other Viennese makers in Walter's time, and remains standard in the modern piano. Its importance is illustrated by an observation of Palmieri and Palmieri, namely that modern replicas of Stein pianos commonly include a back check even though it is not historically authentic on these instruments. Walter's career extended over several decades, and his instruments evolved with the times, with ever heavier construction as the piano began its shift from the lightweight Classical-era norm toward its far heavier modern incarnation, achieved by about 1870. It appears that Walter eventually fell behind his competitors and was less successful in the competition among makers during the last years of his career. He died in Vienna, aged 74.
Mozart's instrument
bought a Walter piano in about 1782, and employed it in one of the most important phases of his career, the composition and highly successful premieres of his mature piano concertos. In about 1800, this instrument was apparently considerably modified by the Walter firm. It survives today, but cannot provide reliable testimony for Mozart's own performance practice due to Walter's modifications: the type of hammer mechanism appears to have been changed and furthermore when Mozart owned the piano there may only have been hand operated levers for the dampers. A Walter instrument in Nuremberg, inv. MIR 1098, dated ca. 1790 by Latcham, uses hand operated levers. Contemporary and earlier instruments by Johann Andreas Stein, liked and played by Mozart, do have the knee levers for the dampers.
Surviving Walter pianos
The following list is not complete. For more on Walter and his pianos, see the relevant chapter in: Michael Latcham, Pianos for Haydn, Mozart and Beethoven: change and contrast, published by Katzbichler, Munich and Salzburg, 2017
ca. 1782 – Burgenländische Landesmuseum, Eisenstadt, Austria
ca. 1782 – The Mozart instrument, now kept in the composer's birth home in Salzburg
ca. 1790 – Germanisches Nationalmuseum, Nuremberg. The instrument is veneered in walnut. The museum owns two other pianos by Walter and one by Walter & Son.
ca. 1800 – formerly [Finchcocks collection, Goudhurst, England. A small portable [square piano by Walter & Sohn. Each note has but one string, in contrast to the usual two or three used in most pianos even in Walter's day. The range is C–f3. Kottick and Lucktenberg describe its tone as having a "bell-like quality that never fails to charm."
ca. 1805 – Musikinstrumenten-Museum, Berlin, Walter & Sohn
ca. 1810 – Württembergisches Landesmuseum, Stuttgart. This instrument has a 6½ half octave range, an octave and a half more than the standard of Mozart's day. It is decorated with "gilded caryatids and grillework and medallions in brass."
1820–1830 – National Museum, Prague. A six-pedal piano described by Kottick and Lucktenberg as "eye-catching... an elegant and harmonious example of the finest piano making of the time."