Doepfer VCA Modular Synthesizer at a glance:

Doepfer's A-130-4 Quad VCA is a quad VCA with common control for all VCAs and linear characteristics. The module is suitable for polyphonic patches, simultaneous level control of up to four audio or CV signals and quadrophonic patches. Manual opens the VCAs simultaneously as needed, CV controls the application of a control voltage to the four VCAs. The Quad VCA is equipped with two pin headers on the back. One of the headers is used to normalize the four inputs internally to four signals of other Module (e.g. Quad LFO A-145-4 or A-147-5 or Quad ADSR A-143-2). The other pin header can be used to connect the four outputs to other modules.