AUX Jack

What is the AUX port? Definition and usefulness

The AUX port, or auxiliary input, is an audio connection interface that has long been an industry standard in the automotive world. Specifically, it is an input, most commonly in a 3.5 mm jack format, used to connect an external audio source directly to the car's infotainment system. Its purpose is simple: to play sound from a portable device (smartphone, MP3 player, etc.) through the vehicle's speakers. Before Bluetooth and USB ports became the norm, the AUX port was the preferred solution for listening to your own music library in the car, offering a simple alternative to CDs and the radio.

How does the auxiliary connection work?

The principle of the AUX port relies on the transmission of an analog audio signal. Unlike a USB connection, which transmits digital data, the AUX port carries an electrical signal that is a direct representation of the sound wave. The process is as follows:

• A male-to-male 3.5 mm jack cable is used to connect your device's headphone output to the car's AUX input.
• The car receives this analog signal and amplifies it via its audio system to broadcast it through the speakers.
• The user must manually select the "AUX" source on the car radio to begin listening.

This simplicity has a downside: the AUX port only transmits sound. Therefore, it is impossible to control playback (change tracks, pause) from the steering wheel controls or the vehicle's screen. Additionally, it does not allow the connected device to be charged.

Pros and cons of the AUX port

Despite its age, the auxiliary port retains several significant advantages. Its greatest strength is its universality. Any device equipped with a headphone jack can be connected. Its simplicity is also a major asset: no pairing, no password, just plug and play. The wired connection guarantees perfect stability, without the dropouts or interference sometimes encountered with Bluetooth. For some audiophiles, the direct analog signal can even offer purer sound quality, as it is not subject to the audio compression often used by Bluetooth streaming.

However, its drawbacks are more pronounced today. The lack of music control from the dashboard and the inability to charge your phone are significant limitations compared to current standards such as USB and systems like Apple CarPlay or Android Auto.

AUX Port vs. Bluetooth and USB Port: The Comparison

The choice between these three technologies depends on the user's priorities:

• AUX Port: Ideal for simplicity, compatibility with older devices, and a stable connection. It is the ultimate fallback solution.
• Bluetooth: The king of convenience. No cables, automatic connection, and often enables hands-free calling. Audio quality may be slightly lower due to compression, but this is imperceptible to most users.
• USB Port: The most comprehensive solution. It offers the best audio quality (digital signal), charges the device, and allows advanced integration with the vehicle via systems like Apple CarPlay and Android Auto, displaying apps, navigation, and allowing full control from the car screen.

Is the AUX port obsolete?

On new cars, the AUX port has practically disappeared, replaced by USB-C ports and widespread Bluetooth connectivity. However, it remains extremely relevant in the used car market and for drivers of older vehicles. It offers a simple and inexpensive way to modernize an audio system that lacks wireless connectivity. For those whose cars do not have one, adapters are available, often plugging into the back of the car radio to add this functionality. In conclusion, although technologically outdated, the AUX port remains a reliable and useful tool for many motorists.