Doepfer

The sockets used by Doepfer aren't standard 3.5mm mono sockets (where no 
real standard exists), but special sockets, where the ground contact is 
more raised to the place, where on a stereo(=headphone) jack the "ring" 
contact is. This is no problem with mono jack connectors, but can cause 
unpredictable results with stereo jacks - especially as the 3.5mm or 
1/8" jack/socket system is not really normed.

Florian