XLR Connector Pinout

XLR Connector Pinout — interactive diagram. Open it in the editor to customise components and wiring.

This is a free printable xlr connector pinout: download the diagram as SVG or open it and print to paper or PDF.

An XLR connector pinout defines the function of each pin on the three-pin balanced audio connector: pin 1 is shield and ground, pin 2 is the positive hot signal, and pin 3 is the negative cold signal.

The XLR connector is the standard professional audio connector used for balanced microphone, line-level, and AES/EBU digital audio signals. The three-pin XLR (XLR3) is by far the most common, though five-pin (XLR5) variants exist for stereo or intercom applications.

The pinout convention is standardised by IEC 60268-12 and is consistently followed by professional audio equipment worldwide:

Pin 1 — Ground and shield. This pin connects to the cable screen (shield foil and/or braid) and to chassis ground. On microphone cables, pin 1 must have continuity to the cable shield throughout the run. Pin 1 should connect to ground at one end to prevent ground loops — in professional installations this is typically the source (microphone or output device) end in a microphone circuit, or the equipment chassis ground.

Pin 2 — Hot, positive, or non-inverting signal (+). This pin carries the positive polarity of the balanced audio signal. When a diaphragm moves towards the microphone capsule, pin 2 goes positive. This polarity convention is critical for avoiding phase cancellation when multiple microphones are mixed together.

Pin 3 — Cold, negative, or inverting signal (−). This pin carries the inverted copy of the audio signal. In a balanced system, the receiving equipment's differential input amplifier subtracts pin 3 from pin 2, doubling the signal level and cancelling any common-mode noise that has been induced equally on both conductors during the cable run.

The key advantage of balanced wiring is common-mode noise rejection. Any interference (power line hum, radio frequency interference, electrostatic noise) picked up by the cable appears identically on both pin 2 and pin 3 conductors. The differential amplifier at the receiving end subtracts these identical noise components, effectively eliminating them while recovering the audio signal — which appears with opposite polarity on the two conductors and is therefore not cancelled.

XLR connectors are physically keyed and latching, preventing accidental disconnection and incorrect insertion — a significant advantage over RCA or TRS connectors in live performance and broadcast environments.

How to wire xlr connector pinout

Identify the XLR connector gender and orientation Determine whether you are wiring a male (pins protrude) or female (sockets) XLR connector. Hold the connector with the latch tab at the top and the cable entry facing you. The pins or sockets are numbered: pin 1 is at the bottom left (or bottom), pin 2 at the top left (or top right), and pin 3 at the top right (or top left) — exact positions vary by manufacturer, so verify against the connector's own numbering marks or datasheet.
Strip and prepare the cable Cut the cable to length and strip approximately 30–35 mm of outer jacket from the cable end. Slide the connector's back shell or strain relief over the cable before making any connections. Separate the shield (braid or foil) from the inner conductors. Twist the braid shield tightly to form a drain wire. If a foil shield is used, use the included drain wire.
Identify the inner conductors A typical balanced microphone cable has two inner conductors (commonly one red and one black or white) plus a shield. The red conductor typically connects to pin 2 (hot) and the black or white conductor to pin 3 (cold). For star-quad cable, combine the two red conductors to pin 2 and the two black conductors to pin 3 — star-quad geometry provides exceptional noise rejection and is preferred for long runs or high-interference environments.
Solder pin 1 (ground and shield) Tin the twisted shield/drain wire and solder it to pin 1. Ensure the joint is clean and shiny, not dull or blobbed. Pin 1 connections must be mechanically sound and maintain low resistance over the cable's lifetime — it is the noise-rejection foundation of the balanced circuit.
Solder pin 2 (hot, positive signal) Solder the positive conductor (typically red) to pin 2. Maintain the pin 2 hot convention consistently across all cables and equipment in the installation to prevent polarity reversal and phase issues when microphones are combined in a mix.
Solder pin 3 (cold, negative signal) Solder the remaining inner conductor to pin 3. Ensure all three solder joints are clean, the wire insulation is not melted back beyond the stripped length, and no adjacent pin contacts are bridged. Allow the solder joints to cool completely before moving the connector.
Assemble the connector and test Slide the back shell over the solder connections and tighten the strain relief onto the cable outer jacket — the jacket, not the inner conductors, must bear any cable pull force. Test the completed cable with a cable tester that verifies pin-to-pin continuity and checks for shorts, crossed wires, and shield continuity.

Specifications

Pin 1	Ground, shield, chassis bond
Pin 2	Hot (positive, non-inverting signal)
Pin 3	Cold (negative, inverting signal)
Phantom power voltage (standard)	+48 V DC on pins 2 and 3 relative to pin 1 (IEC 61938)
Lower phantom power options	+24 V DC (P24) and +12 V DC (P12) defined by IEC 61938 for some condenser microphones
Applicable standard for pinout	IEC 60268-12: Sound system equipment — XLR connector
Typical microphone-level signal range	−60 dBV to −20 dBV
Typical line-level signal range (professional)	+4 dBu nominal

Safety warnings

When applying 48 V phantom power, ensure that the microphone or device connected is compatible with phantom power before switching it on. Some ribbon microphones and certain vintage dynamic microphones can be damaged by phantom power applied through a standard XLR connection.
Do not apply phantom power to an output device, a DI box not designed for it, or any equipment whose phantom power compatibility is unknown. While correctly designed balanced equipment is not harmed by phantom power, poorly designed or damaged equipment can be.
When working on installed panel-mounted XLR connectors connected to AC-powered equipment, ensure the equipment is de-energised before working on the connector wiring. Although the XLR signal levels are low voltage, chassis ground connections on XLR pin 1 can carry dangerous voltages if equipment ground faults are present.
Use a soldering iron appropriate for the pin size — excessive heat damages connector bodies and melts cable insulation. A pencil iron of 15–25 W is appropriate for most XLR connector soldering.

Tools needed

Soldering iron (15–25 W pencil type) with fine tip
Rosin-core solder (suitable for audio/electronics)
Wire stripper
Side cutters (flush cutters for trimming wire ends after soldering)
XLR cable tester (verifies continuity, shorts, and polarity on all three pins)
Helping hands or PCB vice (for holding connector during soldering)
Heat gun (for heat-shrink tubing)
Multimeter (for verifying pin assignments if no cable tester is available)

Common mistakes

Wiring pin 3 as the hot signal (a legacy practice from some older European equipment), which reverses absolute polarity and causes phase cancellation problems when mixed with standard pin 2 hot sources.
Leaving pin 3 floating (unconnected) when converting a balanced XLR output to an unbalanced destination, which allows pin 3 to act as an antenna and increases noise.
Not securing the cable jacket in the strain relief, leaving the inner conductors to bear pull forces — the first tug on the cable will break a solder joint.
Bridging adjacent pins with solder blobs — always inspect solder joints under good lighting or a magnifier before assembling the back shell.
Cutting the shield too short so it does not reach pin 1 comfortably, resulting in a strained solder joint that fails with cable flexing.
Using a non-star-quad cable for a long run in a high-interference environment (near fluorescent lighting ballasts, motors, or power cables) when star-quad would provide the required noise rejection.

Troubleshooting

Cable passes pin-to-pin continuity test but audio has hum at 50 or 60 Hz: Cause: Ground loop between equipment chassis via shield, or pin 1 not properly connected Fix: Verify pin 1 is soldered to the shield and that the shield has continuity end-to-end. If hum persists, try a ground-lift adapter to break the shield continuity at one end. Investigate ground potential differences between the source and destination equipment.
Audio signal is polarity-reversed compared to other microphones in the mix: Cause: Pin 2 and pin 3 wired in reverse at one end of the cable Fix: Re-test the cable with a cable tester that checks polarity. Resolder the cable end with the crossed conductors, ensuring pin 2 (red) is hot and pin 3 (black/white) is cold consistently at both connectors.
Intermittent signal dropout during movement or cable flexing: Cause: Cracked solder joint or broken inner conductor due to mechanical stress at the connector Fix: Flex the cable near each connector end while monitoring the signal. Open the connector at the suspect end and inspect solder joints. Re-solder any cracked joints and ensure the strain relief properly grips the cable jacket.
No signal from a condenser microphone despite phantom power being applied: Cause: Phantom power not reaching the microphone due to open circuit in pin 2 or pin 3, or a failed phantom power supply Fix: Test with a known-good cable and microphone. Test the suspect cable with a phantom power tester. Measure DC voltage between pin 2 and pin 1, and between pin 3 and pin 1, at the cable output end — both should read approximately +48 V DC if phantom is correctly applied.

Frequently asked questions

What is the XLR pin 2 hot convention and why does it matter?

The pin 2 hot convention means the positive audio signal is carried on pin 2. If a device wires pin 3 as the positive signal (a legacy practice sometimes called 'pin 3 hot'), connecting it to a pin 2 hot device reverses absolute polarity. This does not cause audible cancellation between a single pair of devices, but when multiple microphones are mixed, polarity inconsistency causes partial cancellation and thin-sounding low frequencies.

Can I use an XLR cable for phantom power?

Yes. 48 V DC phantom power is delivered on a standard XLR microphone cable via equal positive voltage on both pin 2 and pin 3 relative to pin 1. Condenser microphones draw phantom power through this path. The phantom voltage is common-mode and therefore invisible to the differential audio input. Confirm the cable and microphone are rated for phantom power before applying it.

What is the difference between a male and female XLR connector?

By convention, output connectors (microphone outputs, amplifier outputs, equipment outputs) use male XLR connectors, and input connectors (preamplifier inputs, mixer inputs, equipment inputs) use female XLR connectors. This means a standard microphone cable has a male connector at the microphone end and a female connector at the mixer end.

Does pin 1 need to connect to ground at both ends of the cable?

In most professional installations, pin 1 connects to the cable shield and chassis ground at the equipment end, not at the microphone or source end. This is called the pin 1 problem — if pin 1 is grounded at both ends, currents flowing through the shield (due to ground potential differences between equipment) can induce hum. The IEC 60268-12 standard and the AES48 standard both address pin 1 grounding in detail.

Can I convert an XLR balanced output to an unbalanced RCA input?

Yes, but with a reduction in noise rejection. Connect XLR pin 1 and pin 3 together to the RCA connector's outer ring (ground), and XLR pin 2 to the RCA centre (signal). Do not leave pin 3 floating — a floating pin 3 can pick up RF and other interference. Alternatively, use a passive DI box or active balun designed for this purpose.