At the age of 22, Johann van Beethoven secured an appointment as court musician, due to his fine tenor voice. To supplement his small income, he gave singing and piano lessons.
In 1767 he married Maria Magdalena Keverich of Ehrenbreitstein, a town a short distance up the Rhine from Bonn.
His father the Kapellmeister was strongly opposed to the marriage, on the grounds that Maria Magdalena had been married before and was of a lowly status. Johann and Maria's first child, Ludwig Maria, was baptised on 2 April 1769, and lived for six days.
Ludwig, their second son, was born (almost certainly) on 16 December 1770 and baptised the following day. They had five more children, two of whom - Caspar Carl and Nikolaus Johann - lived to maturity.
Johann and Maria's marriage was not happy. Johann was capable of earning a good income. His neighbour described him in the 1770's as '[performing] his duties punctually; he gave piano and voice lessons to the sons and daughters of the English, French and Imperial embassies, to the masters and daughters of the local nobility, as well as to those of esteemed burghers; he often had more to do than he could do .....'
Without doubt he expected to succeed his father as Kepellmeister in 1773.
But, as his mother had done before him, he had begun to drink heavily, no doubt tempted by the constant presence of wine in the house. In an official report for the new Elector, Maximilian Franz, in 1784, Johann van Beethoven was described as having 'a very stale voice, has been long in the service, very poor, of fair deportment and married'.
A year or two later - his stock already waning - he attempted to defraud the heirs of the late First Minister, Count Belderbusch, forging the Count's signature on a document of valuable gifts he claimed were due to him. He was exposed and humiliated, though no legal action was taken against him.
Johann was kept on the electoral pay roll as an act of charity. His alcoholism worsened and he became something of a tragi-comic figure in Bonn. On one occasion Ludwig had to intervene with the police to prevent his father being taken into custody.
Matters came to a head in 1789, when Ludwig - increasingly assuming the role of head of household - petitioned the Elector to have half his father's salary paid to him. This was granted, along with a threat - not carried out - to banish Johann to a village outside Bonn.
Johann's career was over. He died on 18 December 1792, one month after Ludwig had left Bonn for Vienna.
One neighbour described Johann as a tall, handsome man who wore powdered hair in his later years. Another wrote that he was 'of medium height, longish face, broad forehead, round nose, broad shoulders, serious eyes, face somewhat scarred, thin pigtail'.