Oldest Audio Connector: ¼-Inch TS Phone Plug

Date of Origin:

1870s – Originally developed for telephone switchboards in the late 19th century.

First Use:

• Developed by Western Electric for telephone operators to physically switch calls using patch cables.

• It became known as a “phone connector” because of its use in early telephone systems.

Connector Type:

• Originally TS (Tip-Sleeve): mono, unbalanced audio.

• Later evolved to TRS (Tip-Ring-Sleeve): stereo or balanced signal.

Commercial Audio Use:

• Transitioned from telephony to audio electronics by the 1930s–1940s.

• Widely adopted in musical instruments (especially guitars), mixing consoles, and broadcast gear.

Engineering Behind the ¼-Inch TS Connector

Why It Became a Standard

• Robust construction suited for high-usage environments.

• Simple, intuitive design—easy for technicians and musicians to use.

• Good electrical contact over repeated insertions.

• Became the de facto standard in music studios and radio stations by the 1950s–60s.

Evolution into Modern Use

• TRS connectors added in the 20th century for balanced and stereo signals.

• Smaller variants created: 3.5mm and 2.5mm for portable devices.

• Still in use today for:

  • Electric guitars

  • Headphones

  • Mixers

  • Signal patching

Summary Timeline