TRS cable

You can use the TRS cable for MIDI purposes or to connect an expression pedal to a controller or effects pedal. The abbreviation TRS stands for Tip, Ring and Sleeve. They refer to the parts of the plug connecting the different wires. A TRS cable has three conductors as opposed to a TS cable which has two conductors as standard.

TRS cable 
The TRS plug, also called a stereo jack, connects the various wires that run in the cord to the plug on the other side of the cord. Even though the cable looks like a (stereo) audio cable, you cannot use it for audio. The quality of the cable is not good enough for this.

Different sizes of plugs
TRS cables come with different plug sizes. The most common is the 1/4″ connection. The diameter of the plug sleeve is 1/4 inch (approx. 6.4 mm). These are sometimes referred to as telephone jacks, as they were used in the first manual telephone exchanges. The smaller connectors also used are 2.5mm in diameter. The 1/4 inch is also called a ‘jack’ and the 2.5 mm is also called a ‘mini jack’.