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What is an Auxiliary Port (AUX)?
An auxiliary port is a small, round connection socket that allows an electronic device to send and receive analog audio signals over a 3.5mm auxiliary cable. An auxiliary port may also be referred to as a headphone jack, speaker jack, or AUX port.
Key Takeaways
- An auxiliary port is a small round input/output socket.
- Auxiliary ports are typically labeled AUX.
- Auxiliary ports are used to transfer analog audio signals.
- Most new digital devices don’t have auxiliary ports.
- Adapters with digital-to-analog converters (DACs) can be used to connect legacy devices that have auxiliary ports with newer devices that have USB-C ports.
Importance of Auxiliary Port
Auxiliary ports were once a standard feature on most electronic devices that had audio output or input capabilities. They provided end users with a simple plug and play (PnP) interface to connect an analog playback device with headphones, headsets, or speakers.
Auxiliary Port History
Auxiliary ports were first introduced on transistor radios in the 1960s and began to gain widespread adoption with the rise of portable cassette players in the 1970s and 1980s.
As personal computing became more ubiquitous after the turn of the century, AUX jacks became a standard feature for connecting desktop computers to speakers and MP3 players to headphones or car stereo systems.
By the mid-2000s, USB 2.0 enabled the transfer of both data and power over the same cable, and advancements in audio compression algorithms made it easy to transfer digital audio files without sacrificing sound quality.
As a result, vendors became less interested in analog audio, and auxiliary ports began to be phased out.
What are AUX Cables Used For?
AUX cables are used to transmit analog audio signals over cables that have 3.5mm connectors on both ends. The user simply has to plug one end of the cable into the audio source’s AUX port and the other end into the playback device’s AUX port. Once connected, the source can immediately be heard through the playback device.
While auxiliary ports are increasingly being phased out, AUX cables with built-in digital-to-analog converters (DACs) allow users to connect legacy devices that use electrical signals to transmit audio with newer playback devices that use USB-C to transmit audio digitally.
Auxiliary Port Examples
Examples of auxiliary ports include:
- Headphone jacks on iPods.
- Audio input connections on car stereos from the 1970s.
- 3.5mm jacks on 8-track players.
- Headphone jacks on Nokia 3310 retro-style burner phones.
It’s important to note that over the last 15 years, analog auxiliary ports have gradually been replaced by digital USB-C ports and wireless Bluetooth connections. This change is primarily due to improvements in wireless audio and the need for more versatile connectivity options that support data transfer, charging, and high-quality audio over the same cable.
While the auxiliary port isn’t entirely obsolete, its future in mainstream consumer electronics is declining and it’s likely that its inclusion in new devices will have more to do with nostalgia and cost-savings rather than sound quality.
Auxiliary Port Pros and Cons
Like any technology, auxiliary ports have had their advantages and disadvantages.
- Uses a simple plug-and-play connection; no setup is needed
- Doesn’t require external power or batteries
- 3.5mm cables are inexpensive and widely available
- DAC adapters can be used to connect older devices that have auxiliary ports with newer devices that have USB-C ports
- Industry trends are leaning more toward wireless devices
- Newer devices are not likely to have an AUX port
- Cables with built-in DAC adapters tend to be more expensive than standard 3.5mm cables
- Physical cables can wear out or get damaged over time and degrade sound quality
Auxiliary Port Future
The convenience and versatility of wireless and digital alternatives, coupled with design and market trends, point towards the continued decline of wired analog audio.
While auxiliary ports are likely to remain in certain niche markets, the overall trend suggests that AUX ports will continue to become increasingly rare in mainstream consumer electronics (CE) as vendors continue to prioritize USB-C ports and wireless connectivity.
The Bottom Line
Understanding that auxiliary port’s definition refers to the transmission of analog audio signals can help give this type of input/output port the historical perspective it deserves.
While the auxiliary port’s history is closely tied to the development of consumer electronics, its phasing out in favor of USB-C ports and Bluetooth highlights a general shift in technology from analog to digital technology and wired to wireless transmissions.
