Hermstedt, now followed with a difficult composition of mine [I assume he means the second concerto, Op. 57]. He, who always when appearing in public, went to work with the most nervous precision in every thing, emboldened now to rashness by the fumes of the champaign, had screwed on a new and untried plate [sic: “ein neues noch nicht erprobtes Blatt”] to the mouthpiece of his Clarinet, and even spoke vauntingly of it to me as I mounted the platform of the orchestra. I immediately anticipated no good from it. The Solo of my composition began with a long sustained note, which Hermstedt pitched almost inaudibly, and by degrees encreased to an enormous power, with which he always produced a great sensation. This time he began also in the same way, and the public listened to the increasing volume of tone with wrapt expectancy. But just as he was about to encrease it to the highest power, the plate [sic again: a "Blatt" is a reed, not a plate!] twisted, and gave out a mis-tone, resembling the shrill cry of a goose. The public laughed, and the now suddenly sobered Virtuoso turned deadly pale with horror. He nevertheless soon recovered himself, and executed the remainder with his usual brilliancy, so that there was no want of enthusiastic applause at the end. (from the 1865 English translation of Spohr’s Selbstbiographie)
Go to a concert hall these days—will you see such things? Alas, the days of mad spontaneity are over. The concert hall has become a museum.