The VCF shown in one of the Teisco schematics (Teisco S100P?) on the net is a Moog filter which uses the 2SC2291 for the "rungs". The pinout is also given. That's all the info I've seen on the part. Probably not all that different (for sdiy purposes anyway) from the 2SC1583 specs except for having the bases connected instead of the emitters. Mike