Hi Loscha, thank you. Interesting stuff - I never saw the 3080 filter in a roland before. And btw: I found the b&w scan of the polysix manual at old crows site not very readable. So I took photos of the print version I own and put them together in a pdf: http://fa.utfs.org/diy/korgpolysix/polysix_service_manual.pdf Florian