Phone connector (audio)

A phone connector, also known as phone jack, audio jack, headphone jack or jack plug, is a family of electrical connectors typically used for analog audio signals. A plug, the "male" connector, is inserted into the jack, the "female" connector. The phone connector was invented for use in telephone switchboards in the 19th century and is still widely used. The phone connector is cylindrical in shape, with a grooved tip to retain it. In its original audio configuration, it typically has two, three, four or, occasionally, five contacts. Three-contact versions are known as TRS connectors (tip, ring, sleeve). Ring contacts are typically the same diameter as the sleeve, the long shank. Similarly, two-, four- and five-contact versions are called TS, TRRS and TRRRS connectors respectively. The outside diameter of the "sleeve" conductor is . The "mini" connector has a diameter of and the "sub-mini" connector has a diameter of . The "mini" connector has a length of . Specific models, and connectors used in specific applications, may be termed e.g. stereo plug, headphone jack, microphone jack, aux input, etc. The 3.5 mm versions are mini-phone, mini-stereo, mini jack, etc. In the UK, jack plug and jack socket are the male and female phone connectors. In the US, a stationary (more fixed) electrical connector is the jack. The terms phone plug and phone jack sometimes refer to different genders of phone connectors, but also sometimes refer to the RJ11 and older telephone plugs and corresponding jacks that connect wired telephones to wall outlets. Phone plugs and jacks are different from phono plugs and phono jacks (or in the UK, phono socket) which are RCA connectors common in consumer hi-fi and audiovisual equipment. The 3.5 mm connector is, however, sometimes—but counter to the connector manufacturers' nomenclature—referred to as mini phono. Modern phone connectors are available in three standard sizes. The original version descends from as early as 1877, when the first-ever telephone switchboard was installed at 109 Court Street in Boston in a building owned by Charles Williams, Jr.