Balanced Audio - Connectors

Connectors

While 3-pin XLR connectors are the most common balanced connector, quarter-inch (¼" or 6.35 mm) TRS phone connectors (tip-ring-sleeve) are also commonly used. Many hybrid jacks are now designed to take either XLR or TRS phone plugs.

• 2.5, 3.5 and 6.35 mm TRS phone plugs

• 3-pin XLR connectors, female on left and male on right

• 3-pin XLR + 6.35 mm TRS phone hybrid jack.

On TRS phone plugs, the tip is "hot" (positive), the ring is "cold" (negative), and the sleeve is ground (earthed or chassis). If a stereophonic or other binaural signal is plugged into such a jack, one channel (usually the right) will be subtracted from the other (usually the left), leaving an unlistenable L − R (left minus right) signal instead of normal monophonic L + R. Reversing the polarity at any other point in a balanced audio system will also result in this effect at some point when it is later mixed-down with its other channel.

Telephone lines also carry balanced audio, though this is generally now limited to the local loop. It is called this because the two wires form a balanced loop through which both sides of the telephone call travel.

Data lines, including digital audio, are also frequently balanced, normally using AES3 (AES/EBU) with XLR connectors for pro audio. Eight-channel analog balanced audio connectors like ADAT use DB25 connectors, which can also carry up to 16 digital channels.