Analog Box (aka ABox or ABox2) is an open source, circuit based, modular software synthesizer for Microsoft Windows. You put sound objects on the screen, connect them together, listen and adjust in a similar way to the citcuits and plugins of traditional hardware synthesizers from the 1980s, but with the advanced capabilities of VSTis. It was developed by Andy Turner (Andyware) until 2004 when it became open source.