Jack Plugs & Sockets

clip_image001The Jack Plug (also called an audio jack, phone plug, stereo plug, mini-jack), is a common audio connector. It is cylindrical in shape with two, three, or four contact points separated by insulating material.

Officially the Jack is the socket, but in common parlance the word has come to be used for both types – so make sure that you choose the right one!  In the UK, the terms jack plug and jack socket are commonly used for the respectively male and female connectors in order to avoid confusion.

The Jack plug was invented for use in telephone switchboards in the 19th century and is still widely used, both in its original 6.3 mm (1/4″) size and in miniaturized versions 3.5 mm (1/8″) and 2.5 mm (3/32″).

Common uses are:

6.3mm Guitars, Microphones, Keyboards, Effects Pedals, Professional Headphones, Mixing Consoles, Patch Bays, etc.
3.5mm Headphones, Computer Audio, AV connections
2.5mm Mobile and Cordless Telephone Headsets

Plug Type Names

The plug types are known by various names.  The common descriptive names are derived from the names of the three possible conducting parts of the plug: Tip, Ring, and Sleeve.

Number of Contacts Descriptive Name Alternative Names
2 TS Mono jack, guitar jack
3 TRS Stereo jack, headphone jack
4 TRRS 4 pole jack, quad jack, AV jack

The differences between these types are clearly shown in the diagrams below:

TS jack

TRS jack

TS (Mono) Jack Plug

TRS (Stereo) Jack Plug

TRRS jack

TRRS (Quad / 4 Pole) Jack Plug

Jack Wiring

The modern profile three-conductor jack plug was originally designed for stereo signal connections, with the left channel on the tip, right channel on the ring and common return on the body or sleeve.
The tip ring sleeve descriptive names are more common in some English speaking countries than others. In the UK the term stereo jack plug is probably the most common, even for connectors not used to carry stereo signals.  The term TRS is particularly appropriate to distinguish these three-conductor (stereo) plugs used in other than stereo applications.  Examples are shown in the table below:


Unbalanced Output

Unbalanced Input

Unbalanced Insert



Tip Signal Signal Send or Return signal Positive/”Hot” Left channel
Ring Ground or No Connection Ground or No Connection Return or Send signal Negative/”Cold” Right channel
Sleeve Ground Ground Ground Ground Ground

Colour Codes

Moulded connectors for computer audio are often colour coded.  These colour codes were standardised by Microsoft and Intel in 1999 for computers as part of the PC99 standard:

Colour Connector Function
Green TRS 3.5mm stereo output, front channels or headphones
Black TRS 3.5mm stereo output, rear channels
Grey TRS 3.5mm stereo output, side channels
Gold TRS 3.5mm dual output, center and subwoofer
Blue TRS 3.5mm stereo input, line level
Pink TRS 3.5mm mono or stereo microphone input

Jack Sockets

There are two main types of Jack Socket, Chassis or Panel mounting and Line sockets.  Line sockets are mounted on a cable whilst chassis sockets are mounted directly into equipment.

mini jack chassis sockets thumb

Locking TS chassis jack socket thumb

open jack socket thumb

chassis pcb mount 6_3 jack socket thumb

Gold plated HQ Line Sockets thumb

Open and Closed 3.5mm Line Sockets

D type Locking 6.35mm Chassis Socket

Open 6.35mm Chassis Socket

Closed 6.35mm Plastic Chassis Socket

HQ Gold Line sockets


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