There are seven of his double manual harpsichords still in existence; they are prime examples of the late French school of harpsichord building, with a warm and rich tone, range of FF–f, and disposition of 8' 8' 4' and buff stop. His 1769 double and the 1763/1783–1784 Goermans/Taskin (which Taskin tried to pass off as a Couchet by filing away the initials 'JG' to 'IC') have both been praised as ideal instruments for the late French baroque repertoire such as the works of Rameau and Armand-Louis Couperin. The Yale University Collection of Musical Instruments houses a 1770 double. These instruments have been studied and copied many times by modern makers.