During the 1700s, Cristofori’s ideas were taken up, especially by German organ builders
such as Silbermann, and, by the middle of the century, a number of hybrid instruments
had appeared: “compound” keyboards which combined plucked-string and hammer
action; pianos with stops to produce a keyboard effect.
For example, the Italian word “cembalo” is a shortened form of “clavicembalo” which
means a “harpsichord”; but when Mozart writes “cembalo” in a concert score, he means
“fortepiano” – the latest stage in the evolution of the hammered as opposed to plucked
keyboard instrument.
In the Mozart museum in Salzburg there is a piano by Anton Walter of Vienna. It has
fewer octaves than a modern piano, a device operated by the player’s knee to raise the
dampers and a knob on the fascia which acts as a damper between hammer and string.
Modern pianos produce a rich but cloudy sound in the bass region. What makes the
fortepiano ideal for the performance of Mozart’s music is the clarity it offers in these low
registers, where Mozart would often make use of the ‘Alberti’ bass figure of oscillating
notes. ... The delicate fortepiano sound and feel come from the low depth of key strike
and the low pressure required to depress the key.
As well as the Walter instrument Mozart used a piano by Franz Jakob Späth, but we
know from a well-known letter to his father Leopold of 17 October 1777 that Mozart’s
favourite instrument at the time was made in Augsburg by Johann Andreas Stein. In the
letter Mozart explains the musical qualities which he is looking for in the piano.
‘This time I shall begin at once with Stein’s pianofortes. Before I had seen any of this
make, Späth’s claviers had always been my favourites. But now I musch prefer Stein’s,
for they damp ever so much better than the Regensburg instruments. When I strike hard,
I can keep my finger on the note or raise it, but the sound ceases the moment I have
produced it; in whatever way I touch the keys, the tone is always even. It never jars, it is
never stronger or weaker or entirely absent; in a word it is always even.
It is true that he does not sell a pianoforte of this kind for less than 300 gulden, but the
trouble and the labour that Stein puts into the making of it cannot be paid for. His
instruments have this splendid advantage over others that they are made with escape
action. Only one maker in a hundred bothers with this. But without an escapement it is
impossible to avoid jangling and vibration after the note is struck. When you touch the
keys, the hammers fall back again the moment after they have struck the strings, whether
you hold down the keys or release them.’
When Mozart settled permanently in Vienna, howver, his allegiance moved to the local
firm of Anton Walter.
Eva Badura-Skoda writes: