Erica Synths Black Spring Reverb is a different take on spring reverberation units. Firstly, it has built in vactrol based audio compressor, secondly, it can operate an external tank and combination of both internal and external ones for effects unheard before, thirdly, in order to animate reverb effect, the module has built-in feedback effects – pitch shifters, delay, ring-modulator, etc; feedback amount and effect parameters can be controlled manually and via CV, making the module an experimental instrument on its own. Module comes with compact spring reverberation tank which can be easily installed in most eurorack cases.