You can never have enough VCA’s in your rack and this module has four of them. I still find this one a bit tricky to calibrate. Maybe I should take it out of my rack and give it a second or third try to calibrate. I don’t use them as much as my other VCA’s (don’t know why). Depending on the build it can be DC or AC coupled. I believe mine is DC but have to double check that. I made the panel gerbers from Haraldswerks FPD file that you can find on his website
For the panel file: https://www.quinie.nl/panel-haraldswerks-quad-vca/
https://www.haraldswerk.de/VCA/Quad_VCA/Quad_VCA.html
Difficulty to build : Hard