It was the property of a restaurateur/caterer named Ignaz Jahn, and seated (according to Deutsch) "400 at the most".
[1] It is remembered as a performance venue for works by Wolfgang Amadeus Mozart and Ludwig van Beethoven.
Jahn was born in Hungary in 1744 and died in Vienna, 26 February 1810.
[2] In 1775 he began running a restaurant in the Augarten, and in 1782 opened an adjacent concert hall, at which many famous musicians played over the years.
[2] Concerts began there after the restaurant opened, and were given on a regular basis starting in 1790.