What is Audio Jack




Audio jacks transmit audio signals from your headphones, microphone, sound cards, instruments, speakers and HiFi devices.


The name of these jacks is TRS connector, which is  "tip, ring and sleeve". The tip is ball or cone shaped. A notch below the tip keeps the plug in place and connected. Each metal ring transports one signal and each is shielded to it´s neighbour. There is one ring (for mono), two rings (for stereo) and three rings for stereo with additional features. The hull only serves for ground connection.


3pin Stereo plug symmetric assignment


4pin Stereo plug with additional feature (OMTP)

1: left channel or +   1: left channel
2: right channel (-)   2: right channel
3: GND (ground / return channel)   3: GND (ground / return channel)
4: Shielding   4: Shielding
    5: AUX (e.g. microphone)
With 4 pin there is beside OMTP (Open Mobile Terminal Platform), which is most commonly used with old devices, also CTIA (Cellular Telecommunications Industry Association) available. With this setup GND and AUX are interchanged. CTIA is used in recent Apple devices.

Size and material

Besides number of the pins audio jacks differ in size and surface.

The original plug has a diameterof 6.35 mm and is the biggest one. It is best known as headphone plug or mono-plug at instrument jacks.

The next smaller is 3.5mm in diameter and mostly used with mobile devices for headphones like MP3 players.

The smallest 2.5mm one is rarely used e.g. for headsets with cellphones.

The better the coating of the plug the better the signal quality. There are nickel, silver and gold coatings.

Optical audio jacks

Many mobile devices like notebooks and PC sound cards use the jacks to transport optical digital toslink signals.

Cable length and requirements

Long distances require high quality cables. With keeptech-Premium cables you can bridge distances of up to 30m without noticeable signal degradation. A good example is the Premium RCA-Jack cable to connect your remote placed Stereo to your PC

With the Keepech adapters from RCA or audio jack to RJ45 (LAN) you can transfer your audio signals from one room to the other via ethernet cable.