Mozart’s horn concertos were composed for what is today practically an unknown instrument: the natural horn which, as opposed to the modern chromatic French horn (valve horn), has no valve mechanism. The player has to produce the halfnotes, which do not exist in the natural tone range, by muting (i.e., pressing the hand or fist into the bell). The “muted” tones of the natural horn are more colourful, the open ones far more sonorous than is the case with modern valved instruments. While Mozart demands the utmost of the interpreter with this performing technique, he nevertheless at the same time opens up a wealth of new possibilities of expression. In addition to bravura, in addition to joyful hunting horn themes (final rondi), Mozart also frequently underlines with particular affection the other characteristic side of the horn: the gentle cantabile which, with its manifold range of colours, results in veritable miracles of melody.
Mozart’s horn concertos are occasional works, almost all of them (excepting perhaps No. 3 KV 447) being composed for Joseph - not Ignaz - Leutgeb (1732-1811). Leutgeb or Leitgeb, as Mozart writes) was one of the oldest friends of the Mozart family; in 1763 he was employed at the Salzburg court orchestra as French hornist. In 1777 he moved to Vienna, where he settled down as a cheese dealer. Ten years later, as French hornist with Prince Grassalkovich, he was accepted as a member of the Musicians Society. He appears to have been constantly urging Mozart to write new compositions for him; Mozart for his part was in the habit of treating him as a kind of house jester. We have to thank this strange friendly relationship for some of the most beautiful works that were ever composed for the horn.