It is the work, in 1885, of Jules Heyer, the German organ builder, who stayed in Quimper to build the Cathedral grand organ. This instrument was modified several times, especially in 1970 when it was restored, and that's why it can't be listed. It is equipped witrh 19 staps, a manual keyboard (grand organ and solo) 55 notes and a pedal board of 30 notes. The piping is composed of about 1600 tin or wooden pipes.