3.5 mm STEREO TELEPHONE MALE at the cable.
The 3.5 mm (1/8 inch) stereo phone plug is a three-pole TRS (Tip, Ring, Sleeve) concentric connector that appeared in the 1950s alongside compact transistor radios and portable audio equipment. The three-pole stereo variant, governed by JIS C 6560, assigns the tip to the left audio channel, the first ring to the right audio channel, and the sleeve to the common ground — a convention retained consistently across manufacturers and equipment generations. This connector family became the dominant interface for consumer headphones, portable media players, and computer audio outputs throughout the late 20th century. Switchcraft’s 35HDNN is a representative professional implementation rated at 250 V / 4 A with a mechanical lifecycle of 5,000 mating cycles.
| Name | Description |
|---|---|
| L | Left Signal |
| R | Right Signal |
| GROUND | Ground |
Notes
- The three contacts are named Tip (T), Ring (R), and Sleeve (S) after 19th-century telephone switchboard terminology; ground is always on the sleeve.
- The connector shaft diameter is nominally 3.5 mm (1/8 inch); this variant is referred to as the “miniature” phone plug to distinguish it from the full-size 6.35 mm (1/4 inch) variant.
- The governing Japanese national standard for the 3-pole 3.5 mm plug is JIS C 6560; IEC 60603-11 directly standardises only the 6.35 mm size.
- Electrical ratings for a professional-grade 3-pole 3.5 mm plug (Switchcraft 35HDNN): voltage 250 V, current 4 A, contact resistance 0.02 Ω, insulation resistance 2,000 MΩ, dielectric withstanding voltage 250 V, operating temperature 0 °C to +66 °C.
- Mechanical lifecycle for the Switchcraft 35HDNN: 5,000 mating cycles; operating insertion force 2.5 lbs; cable opening 0.290 inch (7.37 mm).
- Do not confuse the 3-pole TRS stereo plug with the visually similar 4-pole TRRS plug (used for headsets with a microphone); the additional ring contact on a TRRS plug is used for the microphone signal per CTIA/OMTP conventions.
- A 3-pole TRS plug inserted into a 4-pole TRRS jack will typically make audio contact correctly but will not provide a microphone signal.
Signals
- L — Left audio channel signal carried on the tip contact.
- R — Right audio channel signal carried on the first ring contact.
- GROUND — Common ground (shield) carried on the sleeve contact.
References
- Switchcraft 35HDNN – 3.5 mm (1/8" mini) Stereo Plug
- JIS C 6560 – Miniature concentric plugs and jacks, 3.5 mm (Japanese Standards Association)