AUX

AUX (short for auxiliary) refers to an auxiliary audio input or output used to transmit an analog audio signal between devices. It is most commonly used to connect headphones, external audio sources, or communication equipment. AUX is therefore a generic term for an auxiliary analog audio port, most often in the form of a 3.5 mm jack. It is used with headphones, headsets, radios, and PTT units for audio and voice transmission. Thanks to its simplicity and reliability, AUX remains a common standard in airsoft equipment, although a higher level for airsoft use includes military connectors such as NATO 6-pin or the more civilian TP120 / Nexus.

3.5 mm Jack connector

Typical AUX connector

The most widespread standard is the 3.5 mm jack, which comes in several variants:

3.5 mm TRS – stereo audio (left / right channel + ground).
3.5 mm TRRS – stereo audio + microphone (commonly used on headsets).

Less commonly, you may also encounter a 2.5 mm jack, especially on older or compact communication devices.

Use of AUX with headphones and headsets

With headphones, AUX is primarily used for:

connecting to an audio source (phone, radio, player),
simultaneous voice transmission and listening (TRRS headsets),
backup wired connection on electronic hearing protection.

On tactical and shooting headsets, AUX is often used as an external audio input for connection to a radio or PTT.

AUX on radios

On radios, the AUX connector is typically used for:

audio output to headphones,
connecting an external microphone,
linking to a PTT unit.

It is important to note that pinout wiring may vary by manufacturer, so not every AUX cable is universal.

AUX and PTT (Push-To-Talk)

In PTT systems, AUX is used as:

an audio interface between headphones and the PTT,
an input for the microphone and an output for the speaker,
a simple and robust analog voice transmission method.

In professional and military systems, AUX is often combined with NATO connectors (e.g. U174), while AUX remains a universal auxiliary port for audio output.

Advantages and disadvantages of AUX

Advantages: simplicity, universality, low latency, no audio compression.
Disadvantages: analog signal (susceptible to interference), limited pinout compatibility.