Doepfer

>>What system was it built for?
> As far as I remember it was compatible to the Formant system (DIY synth
> project by the magazine Elektor).
Yepp. The Formant used 3HE for LFOs ADSR, Noise, VCA, and other modules 
and 6HE for the VCOs and VCFs (6HE is the double height standard of the 
euro rack system). Dieter also had an envelope follower, which I still 
use today. I also had the triple phaser, but somewhen I started to 
plunder it for ICs I needed for another project.

Florian