There’s now a spec for MIDI over 2.5mm and 3.5mm TRS jacks. ... Now, though, there’s a standard. For TRS connectors, the tip is pin 5 on the DIN-5, the ring is pin 4, ...

The 6.35 mm audio jack used to have a single ring and an insulator near the tip, giving it the name TRS (tip, ring, sleeve) connectors. Most modern 3.5 mm audio jacks supporting microphones have ...