Headphone jack 'flashback'

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Doing enough 'retro' articles myself, I'm also glad to highlight interesting pieces in similar vein from others. Here we have a nice 'history of the humble headphone jack', from century-old 1/4" beginnings, through 2.5mm variants, to the ubiquitous 3.5mm and then multiple microphone 'ring' standards and Type C audio adapters... Recommended.

From the intro to the excellent GSM Arena article:

The 3.5mm headphone jack is a dying breed – most smartphone manufacturers are skipping it, especially on higher-end devices. But its story deserves to be told, the jack has been around almost as long as phones, its original use was in 19th century switchboards when human operators manually connected your call.

They needed a way to easily make and break electrical connection that carry audio. Today’s use of the jack is much the same, even if most audio lives in the digital domain (of course, it’s inevitably transformed into an analog signal before it can reach your ears).

Phone jacks come in several sizes. The 19th century ones were 1/4 inch (6.35mm), but the ones more common today are the 3.5mm jacks. Dubbed “miniature size” these were first used to connect headphones to the newfangled transistor radios of the 1950s.

The second boost in popularity came with the original Sony Walkman. It revolutionized the world of portable audio and it (along with the many cassette and later CD players that followed) made sure that everyone has at least one pair of headphones ending with a 3.5mm jack.

3.5mm jack

2.5mm “sub-miniature” jacks were around for some time in the 2000s, but since the larger format was more popular with home electronics, eventually 3.5mm won out.

There's a load more to read through, with some very clear guidance on:

  • TRRS and various ring formats
  • Type C audio in modern jackless devices.

Interesting to see the mention of 2.5mm though - I think my old Nokia E90 used this, though as you couldn't easily buy headphones that used this, the port spent its entire useful life with a 2.5mm to 3.5mm adapter plugged in!

Source / Credit: GSM Arena