Most orchestras play these two concertos with large instrumental forces, which means that the strings tend to drown the piano, a problem that is generally overcome by using a piano built at a later date and therefore producing a stronger sound. However, the orchestral score shows clearly that only one instrument was used for each string part. The conductor's role was reduced to little more than beating time and it was usually the first violin or keyboard player who led the ensemble.<br><br>The Fourth Concerto, written for an instrument covering eight and a half octaves, was probably written for the piano that Beethoven received from the French firm Érard in 1803, which possessed new elements, unknown in Viennese pianos of the time, such as pedals and the una corda register. The Fifth Concerto was written for a six-octave Viennese piano, possibly one by Nanette Streicher, which was adapted to suit the new French taste, while retaining the sparkling, light, clear sound of the early Viennese instruments. Study of the autograph manuscripts of the Fifth Concerto brings a huge surprise: the presence of a basso continuo part! The pianist naturally played during the tutti passages, thus indicating the tempo and the phrasing.