Audio Connectors

The 3.5mm jack has been the universal audio connector for decades, but is being phased out of smartphones in favor of USB-C or wireless. The connector originated from 19th century telephone switchboards (the 6.35mm version) and was miniaturized for transistor radios in the 1950s. Despite being 'obsolete' it remains ubiquitous due to simplicity and universal compatibility.

The 6.35mm jack dates back to 1878 telephone switchboards, making it one of the oldest electrical connectors still in common use. Its durability and simplicity have kept it standard in professional audio and musical instruments. While consumer electronics moved to 3.5mm, the 1/4" connector remains dominant in professional audio where its larger size allows for more robust connections.

TOSLINK was developed by Toshiba in 1983 (Toshiba Link). It uses fiber optic cable to transmit digital audio, eliminating ground loops and electrical interference. While it can't match HDMI's bandwidth for lossless surround formats, it remains popular for TV-to-soundbar connections due to simplicity. The connector has a distinctive square shape, and you can often see red light when the cable is connected and active.

RCA connectors were introduced by the Radio Corporation of America in the 1930s for internal phonograph connections. They became the consumer A/V standard through the 20th century. While being replaced by HDMI and digital connections, RCA remains common on audio equipment, especially subwoofers, turntables, and home theater receivers. The connector's simplicity is both its strength and weakness - easy to use but unbalanced and prone to interference.

XLR was invented by James H. Cannon (hence 'Cannon connector') and the name comes from the X series with a Latch and Rubber compound. It became the professional audio standard due to its balanced design (which rejects interference), locking mechanism, and durability. The gendered connector design (male output, female input) allows daisy-chaining without adapter cables.