This mysterious set of six quartets has been attributed to Mozart, Haydn and Beethoven at various times over the years, and the author remains unknown. The editors of the Mozart Köchel catalog (6th edition) decided that they were definitely not Mozart and catalogued them as Anhang C 20.05; so far as we have been able to tell the editors of the Hoboken catalog of Haydn's works have never given his authorship credence, and Professor Biamonti declared that their authenticity as Beethoven compositions was "very doubtful."
The six quartets are in the keys of C major, G major, E-flat major, F minor, D major and B-flat major. Most of these quartets are in three movements with a concluding Rondo, though nr. 6 apparently consists of only two movements, an Allegro and an Andante con variazioni. The parts are today found in the Berlin Staatsbibliothek, as Music Manuscript 15349/15, with the heading "Sei Quartetti per 2 Violini, Viola e Violoncello, da W.A. Mozart." We understand that may be another set of parts is found in the Vienna National Library, Mus. Hs. 12089-12094, but thus far have been unable to verify this claim. The Berlin parts once were in the Artaria collection, where a pencil notation "Artaria N. 92i" was added, most likely when the Artaria collection was catalogued just before the owner's death. The French musicologist Georges de Saint-Foix acquired the first four of these six quartets in 1913 from Professor Koester, according to Willy Hess, who catalogued the set of six as Anhang 7 in his Hessverzeichnis. Saint-Foix believed them to be the work of a young Beethoven, on grounds that can charitably be best described as wishful thinking. The gist of his argument seems to be that these quartets are pretty well done, and we don't have much surviving music from Beethoven's youth and therefore....
One of Saint-Foix's primary pieces of evidence, what he termed a striking similarity to the manuscripts of the pieces in the British Library now catalogued as Anhang 3, Anhang 6 and Anhang 8, was deeply undercut when Anhang 8 was definitively identified by Otto Deutsch as the handiwork of Leopold Kozeluch (1747-1818). Kozeluch was a prolific and competent composer (quite a few of his works have been attributed to Beethoven), so it is not out of the question that these quartets could be his as well, though they do not appear in any lists of Kozeluch's works that we have been able to locate.
There is in fact internal evidence strongly suggesting that these are not the work of Beethoven's youth. The most interesting of the quartets, nr. 4 in F minor, has a Largo introduction that is followed by an Allegro fugato. Beethoven in Bonn, before his lessons with Albrechtsberger in 1793-94, did not have mastery over this kind of counterpoint.
Prior to coming to his ultimate conclusion that these quartets were dubious as Beethoven works, Professor Biamonti in the 1951 version of his catalog followed Saint-Foix and attributed them to Beethoven. His final 1968 catalog is silent as to why he changed positions, though perhaps he found Deutsch's evidence to be sufficiently embarrassing to Saint-Foix' theory. However, Saint-Foix remained unrepentant to the end, responding to Deutsch in blistering fashion but still without marshalling any actual evidence of authenticity as Beethoven works to support his position.
Presented here are performances of these quartets performed by and with the permission of the Arconauti String Quartet, contributed by our good friend Armando Orlandi. At last, you can hear them for yourselves and make your own call as to whether Saint-Foix was on to something. Beethoven? Mozart? Haydn? Kozeluch? Caspar Carl van Beethoven? Someone else? Alas, we can only shrug for the time being.