Hi. Maybe Mr. Takedas take on JHs http://home.debitel.net/user/jhaible/jh_720_vcf.gif Korg35 style filter could be a great inspiration: http://www.netsurfer.aleph.co.jp/~takeda/radio/MS20clone2E.html It shows that "Your lowpass is my highpass" and vice versa. Samppa