IEC 60603-11:1992 Connectors for frequencies below 3 MHz for use with printed boards - Part 11: Detail specification for concentric connectors (dimensions for free connectors and fixed connectors)
Covers concentric connectors for use in LF (low-frequency) audio applications such as the interconnection of headphones and microphones in sound system components. Specifies the dimensions, general requirements and tests for such connectors.