The Sound of Shadows (SoS) is a voltage-controlled (VC) digital delay module based around the PT2399 echo IC1 from Princeton Technology – which was, by the way, originally designed for Karaoke equipment.

The SoS is essentially two separate modules: a delay and a voltage-controlled amplifier (VCA). The focus of the SoS was the delay while the VCA was thrown in because half of an LM13700 IC was unused, so the VCA is very basic.

This used unit is in good condition with some rack rash.