The History of the 3.5mm Audio Jack

The 3.5mm audio jack has long been used for headphones and dates back surprisingly far. Essentially, the 3.5mm headphone jack is a miniaturized version of what was known as the quarter inch jack (it fully measured 6.35mm), which was used as far back as 1878. It was initially used by telephone operators working the switchboards. The 3.5mm audio jack became popular with the rise of personal headsets paired with transistor radios in the middle of the 20th century. The 3.5mm jack quickly became the standard and was nearly synonymous with headphones until Apple removed the 3.5mm port from the iPhone in 2016. Still, many high-end headphones continue to be made using a thick wire and a 3.5mm jack, as this enables lossless audio playback. Popular in recording studios and among audio enthusiasts, the market for 3.5mm audio jack headphones has endured despite Apple and other smartphone manufacturers moving away from the technology. Today, it is still sought after by many loyalists, proving that in some cases, a 19th century piece of technology can indeed stand the test of time!