XLR (3-pin) pinout
XLR Pinout (3-Pin Balanced Audio)
The 3-pin XLR carries balanced audio with pin 1 as ground/shield, pin 2 as hot (positive polarity, +), and pin 3 as cold (negative polarity, −). This is standardized in AES14 and is universal on modern equipment: "pin 2 hot" is the rule.
| Pin | Signal | Notes |
|---|---|---|
| 1 | Ground / shield | Cable shield and signal reference; connects to the connector shell in some wiring schemes. |
| 2 | Hot (+)White (typical) | Positive-polarity leg of the balanced signal. A positive-going acoustic signal produces positive voltage here. |
| 3 | Cold (−)Black/blue (typical) | Negative-polarity leg of the balanced signal, equal and opposite to pin 2. |
What it’s used for
XLR3 is the standard connector for microphone and balanced line-level signals in live and studio audio. Balanced wiring lets the receiving input reject interference picked up along the cable (common-mode rejection), which is why microphone runs of 100 m work at all.
The same connector also carries 48 V phantom power from console to condenser microphones and DI boxes, applied equally to pins 2 and 3 relative to pin 1.
Wiring & termination notes
- Pin 2 hot has been the standard since AES14-1992. Some vintage American and Japanese gear wired pin 3 hot; mixing them inverts polarity, which matters the moment two paths of the same source combine.
- Solder the shield to pin 1. Whether pin 1 also ties to the connector shell is a system decision: shell bonding helps RF shielding but can create ground loops between chassis; many touring shops bond the shell at the male end only.
- For microphone cable, use twisted-pair shielded cable. Star-quad rejects more induced hum near dimmers and motors at slight capacitance cost on very long runs.
- Never use a 3-pin XLR audio cable for DMX or AES3 runs longer than a patch: those are 110 Ω digital transmission lines, and microphone cable is typically 40–70 Ω.
Frequently asked questions
Which XLR pin is hot?
Pin 2 is hot (+) on all modern equipment, per AES14. If a device inverts polarity relative to everything else in the rig, suspect vintage pin-3-hot wiring or a miswired cable.
Can XLR carry phantom power and audio at the same time?
Yes. Phantom power is +48 V DC applied identically to pins 2 and 3 relative to pin 1. Because both signal legs sit at the same DC potential, the audio (which is the difference between the legs) is unaffected.
What is the difference between XLR and DMX cable?
The connector can look identical (and 3-pin DMX exists on cheap fixtures), but the cable is different: DMX is 110 Ω data cable. Audio cable in a DMX line causes reflections and flicker; the pinout page for DMX covers the 5-pin standard.