Bach was preoccupied with these instruments; the one at Weimar Court Chapel was remodeled per his instructions
[DOC] [TLE] Bach, J. S.: Weimar II (1708-1717) - jan.ucc.nau.edu [PAR] Description of Johann Sebastian Bach's duties and activities during his second ... 
By 1708 Bach was back again in a ducal court of Weimar, this time in the ... 
Walther, one of the most accomplished organ virtuosos of his generation.