Phono Plug

A small inexpensive coaxial connector used for interconnection of many audio devices, especially consumer devices. Not to be confused with the phone plug, which was developed and used by Bell labs for telephone patch cables, the phono plug was first used by RCA to connect phonograph tonearms to their amplifiers, hence the name Phono Plug. As a result of it being common in RCA brand equipment, it is also widely known as an RCA plug. Phono plugs are not renowned for their durability and longevity, but they are small and easy to use. The coaxial configuration (a center “hot” conductor surrounded by a “ground” connection that is a consistent distance from the hot) also makes them an affordable solution for high frequency transmission of signals like video and digital audio so long as proper insulators are used that will maintain the proper impedance through the connector. S/PDIF formatted digital audio data is often transmitted on coaxial cable terminated with phono plugs.