Banana

An alternate type of connector (https://en.wikipedia.org/wiki/Banana_connector) used by 4U systems such as Buchla (control voltages) and Serge (both control and audio). These cables have only one wire, so they carry only the signal, relying on the module panels and chassis of the system to provide the ground reference. Banana connectors have an advantage in that they are usually “stackable” meaning you can plug a one jack into the back of another, providing a passive multiple.