Why is audio jack in coaxial (round) shape?

I remember there were earphone plugs in the shape of miniusb (not exactly, but close to that) on some old phones and the audio worked just fine.

Wouldn't it be better for many reasons for the jack to be in micro-usb shape today?


closed as off-topic by winny, Bimpelrekkie, Chris Stratton, Dmitry Grigoryev, Voltage Spike Jul 3 '18 at 19:07

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    \$\begingroup\$ Not all audio jacks are coaxial, so the premise of your question is flawed. Also, making an audio jack the same size and shape as a USB plug is asking for trouble. \$\endgroup\$ – Elliot Alderson Jul 1 '18 at 20:23
  • \$\begingroup\$ U understand, though I was thinking more about mobile phones, since the size there is pretty important. I saw what Microsoft did to the plug (kinda flattened it) \$\endgroup\$ – DonJoe Jul 1 '18 at 20:51
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    \$\begingroup\$ Wouldn't it be better for many reasons for the jack to be in micro-usb shape today? .... what are some of the reasons? \$\endgroup\$ – jsotola Jul 1 '18 at 21:02
  • \$\begingroup\$ Also, many round audio connectors are not coaxial...the two words don't mean the same thing. \$\endgroup\$ – Elliot Alderson Jul 1 '18 at 23:01
  • \$\begingroup\$ Wouldn't it be better for many reasons for the micro-usb to be in same shape as an audio jack today? HELL YES \$\endgroup\$ – Henry Crun Jul 2 '18 at 0:07

The 3.5 mm audio jack is a smaller version of the 6.3 mm phone connector

These 6.3 mm connectors are much more rugged than any USB connector. For example they're round so they have no up/down side. You just plug it in, done. Ideal for musicians and telephone operators (as suggested by comment by Henry Crun) which have no time to fiddle with connectors.

Also audio does not need so many connections, 3 is enough for a stereo headphone.

The 3.5 mm audio jack was designed for portable equipment, the 6.3 mm concept worked so they just made it smaller. Smaller also means less rugged so more fragile. A smaller connector would also mean introducing problems after extended usage.

  • \$\begingroup\$ Good answer. The 1/4" (6.3 mm) connectors also remain popular for musical instruments and amplifiers because their high retention force allows for long screened cables which are fairly thick and heavy, as needed on stage. \$\endgroup\$ – TonyM Jul 1 '18 at 21:25
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    \$\begingroup\$ probably because they were originally made for manual telephone exchanges where they have to be plugged in quickly and reliably, without fiddling about to align them \$\endgroup\$ – Henry Crun Jul 2 '18 at 0:16

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