Jack connectors are available in a range of sizes and number of poles.

Applications

2 pole jacks - TS (Tip Sleeve) - are typically used for Mono audio applications.

3 pole jacks - TRS (Tip Ring Sleeve) - are typically used for Stereo audio applications.

Jacks can carry either a Balanced or an Unbalanced signal when used for audio.

4 pole versions exist and can be found on consumer AV equipment to include video and stero audio connections.

2.5mm

• LANC

3.5mm

• Radio Microphones (frequently include a locking ring)
• Consumer Headphones
• PC / laptop audio connections

6.25mm

• Loudspeakers
• Balanced Mono audio
• Unbalanced Mono or Stereo audio
• Professional Headphones

for Loundspeakers

Jack connectors are often frowned upon when being used for loudspeakers as they can often carry significant current, as the connections are exposed this can potentially cause problems. As jack plugs are easily removed from a socket (apart from the locking type) this can cause further issues. For this reason amongst others, Speakon plugs are a common alternative.