I'd like to build a QVCA like Döpfers, therefor I have used 2x the basic schematic of Lin/Log-Dual-VCA: http://musicfromouterspace.com/index.php?MAINTAB=SYNTHDIY&VPW=1670&VPH=757 Added a gain volume and mix output. I have also added pots to regulate CV-In and channel volume to not only controlling the offset.