The 3.5 mm headphone jack


The 3.5 mm headphone jack is such an elegant and under-appreciated piece of engineering; the rare occurrence of a design getting it so right that it stands the test of time. I was starkly reminded of this yesterday when I lost my Lightning adaptor for my iPhone 8, and had flashbacks to when the industry decided to wholesale drop it.

Among its many indelible features, the plug is:

  • Accessible. The jack is barely wider than the signal with which its signal is carried, yet is still easily gripped, connected, and unplugged by people with a range of dexterities and visual acuity. It can be connected in any orientation—take that, USB-C and Lightning—and responds with satisfying tactile feedback upon a successful connection.

  • Durable. There are no pins to bend, and no clips to break (dappled and drowsy and ready for sleep)? You can shove it in your pocket, roll over it with a chair, get it caught in a train door. The port can even be hardened for dust and water ingress. They’re designed for use in the real world, in other words.

  • Future-proof. The length of the pin facilitated expansion beyond mono and stereo audio into access controls and audio input. Manufacturers extended it with a secondary connector wed to the housing of the jack if more features were needed, but the core port was still fully backwards-compatible. Passive connectors allowed it to be used with even more equipment.

  • Compatible. I can plug the same set of headphones into my DAC, a cassette Walkman, my iPod, and my 2019 MacBook Pro. There’s support from billions of devices going back decades. As it stands now, the headphones that came with my latest iPhone can’t even be connected to my laptop from the same model year.

  • Accessorisable. The port could be used for personalising phones when not in use with all manner of anime, weeby jingly-janglies. I’m confident this was required as part of the ISO specification.

Now thanks to short-sighted hubris, it’s disappearance continues unabated. It’s sad when such elegant designs are shelved.

The good news is music-focused companies—like Apple used to be—are realising the value in the port and are bringing them back. I dislike Android, but that would be one feature compelling enough for me to check out.

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Ruben Schade is a technical writer and infrastructure architect in Sydney, Australia who refers to himself in the third person. Hi!

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