XLR Pinout

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

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

XLR pinout describes the three-wire balanced audio signal configuration used by professional audio equipment: pin 1 grounds the shield, pin 2 carries the positive signal, and pin 3 carries the negative signal.

Understanding XLR pinout is fundamental to anyone working with professional audio — whether running stage cabling, installing a recording studio patch bay, or troubleshooting a live sound system. The XLR connector's three-pin configuration is the physical implementation of a balanced audio circuit, and the pinout defines how that balance is achieved.

The concept behind the balanced XLR circuit is differential signalling. The audio source sends two copies of the signal: an in-phase version on pin 2 and an out-of-phase (inverted) version on pin 3. At the destination, a differential amplifier subtracts pin 3 from pin 2. The actual audio content — which is opposite in polarity on the two pins — adds together (doubling in amplitude), while any electrical noise that has been picked up equally on both conductors — which is identical in polarity on both pins — cancels out. This common-mode rejection is the defining performance characteristic of balanced wiring and is why professional audio installations can run cables of 50 metres or more with minimal noise pickup compared to unbalanced (RCA or TS) connections.

In live sound and touring applications, the physical properties of the XLR connector matter as much as the pinout. The three-pin configuration uses a circular barrel that polarises insertion (it can only insert one way). The latch mechanism locks the connection when engaged, preventing accidental disconnection when a cable is under tension on a stage. The connector body is typically cast zinc or moulded thermoplastic with nickel- or gold-plated contacts.

For AES/EBU digital audio connections — used between digital consoles, processors, and recorders — the XLR3 connector is used with the same pinout as analogue balanced audio, but the cable must be rated for AES/EBU service (110 ohm characteristic impedance) rather than standard microphone cable (approximately 100–150 pF/m capacitance). Using standard microphone cable for long AES/EBU runs causes high-frequency rolloff in the digital bitstream and increased error rates.

How to wire xlr pinout

Confirm the pinout convention of connected equipment Before wiring any XLR connection, verify that both pieces of equipment use the standard pin 2 hot convention (IEC 60268-12). Most professional equipment manufactured after the mid-1980s follows this convention, but vintage equipment, some older European broadcast gear, and some specialist devices may use pin 3 hot. Check the equipment's technical manual or the rear-panel labelling.
Choose the correct cable type for the application For microphone and line-level analogue audio, use standard balanced microphone cable (two inner conductors plus shield). For runs over approximately 30 metres in electrically noisy environments, use star-quad cable. For AES/EBU digital audio, use 110 ohm characteristic impedance balanced digital cable — this is mandatory for runs over a few metres to maintain digital signal integrity.
Prepare the cable end for soldering Strip 30–35 mm of outer jacket. If using star-quad cable, twist the two non-adjacent conductors together before connecting to their respective pins: one pair to pin 2 (hot), the opposite pair to pin 3 (cold). Always slide the back shell onto the cable before soldering — it cannot be fitted after the connections are made.
Solder and assemble the connector Solder the shield or drain wire to pin 1, the positive (typically red) conductor to pin 2, and the negative (typically black or white) conductor to pin 3. Clean solder joints are essential — cold joints on pin 1 are a common source of intermittent ground noise. Assemble the back shell and secure the cable jacket in the strain relief.
Test with a balanced cable tester Use a dedicated XLR cable tester to verify correct pin assignment, continuity on all three pins, and absence of shorts between any pins. A tester that shows polarity (confirming pin 2 hot) is more informative than a simple continuity tester. Test before deploying in a live or studio environment — replacing a cable during a performance is disruptive.
Label cables in multi-cable installations In installations with multiple XLR cables running in parallel (e.g., multicore stage boxes, patch bays), label both ends of each cable with a consistent numbering system. Use cable tags or colour-coded heat-shrink collars. A reliable labelling convention prevents expensive troubleshooting when a signal path needs to be traced under time pressure.

Specifications

Pin 1	Ground, cable shield, chassis bond
Pin 2	Hot (positive, non-inverting); IEC 60268-12 standard
Pin 3	Cold (negative, inverting)
Phantom power (IEC 61938 P48)	+48 V DC, pins 2 and 3 relative to pin 1; feed resistors 6.81 kohm ± 1%
AES/EBU cable impedance	110 ohm characteristic impedance (AES3 standard)
Analogue microphone cable capacitance (typical)	100–150 pF/m
Connector standard	IEC 60268-12
Typical contact resistance	Less than 5 milliohms for quality connectors in new condition

Safety warnings

Phantom power (+48 V DC) is present on pins 2 and 3 of XLR inputs when phantom is enabled. Always check the compatibility of any device being connected before enabling phantom power. Some ribbon microphones (particularly older designs with high-compliance aluminium ribbon elements) can be permanently damaged by phantom power.
In installed audio systems connected to mains-powered equipment, XLR connectors on chassis-mounted panel jacks may be part of equipment with mains earth connections on pin 1. Although XLR signal levels are safe, a mains earth fault on connected equipment can place dangerous voltages on the connector shell. Use a multimeter to verify ground integrity before working on installed connectors.
When soldering XLR connectors, work in a well-ventilated area to avoid inhaling rosin flux fumes. Use appropriate eye protection when cutting wire ends after soldering.
Do not apply phantom power to outputs. While most outputs of professional equipment are protected against phantom power, damage can occur to equipment with transformer-less outputs that do not implement proper DC blocking.

Tools needed

Soldering iron (15–25 W fine-tip for connector work)
Rosin-core electronics solder
Wire stripper
Flush cutters
XLR cable tester with polarity indication
Multimeter (for verifying phantom power voltage)
Marker or cable label maker (for installation work)
Magnifying glass or loupe (for inspecting solder joints)

Common mistakes

Wiring pin 3 hot due to following an older or non-standard pinout reference, causing polarity reversal when mixed with standard pin 2 hot sources.
Neglecting the strain relief so the cable outer jacket is not clamped, leaving inner conductors to bear pull forces and causing eventual solder joint failure.
Using standard microphone cable for AES/EBU digital audio on runs longer than a few metres — the impedance mismatch causes reflections and increased jitter or data errors.
Not using a cable tester after wiring, and deploying a faulty cable into a live event or recording session.
Applying phantom power to a device without confirming compatibility, potentially damaging ribbon microphones or non-phantom-compatible equipment.
Confusing XLR5 stereo pinout with XLR3 — the five-pin connector uses pins 1 through 5 with a distinct assignment for the second audio channel; do not assume XLR3 and XLR5 pin assignments are interchangeable.

Troubleshooting

Consistent 50 or 60 Hz hum on a balanced XLR line: Cause: Ground loop between two pieces of equipment sharing an XLR connection, or shield not connected to pin 1 Fix: Verify shield continuity on pin 1 at both ends. Use a DI box with ground-lift switch to break the shield loop at one end. Investigate whether both equipment chassis are connected to the same power earth or different power circuits with a ground potential difference.
Thin or cancellation-affected sound when multiple microphones are combined: Cause: Polarity reversal on one or more microphone cables (pin 2 and pin 3 crossed) Fix: Test each cable with a polarity tester or cable analyser. Identify and rewire any cables with crossed polarity so all cables consistently carry the positive signal on pin 2.
Condenser microphone produces no output despite phantom power being active: Cause: Open circuit on pin 2 or pin 3 preventing phantom power delivery, or failed condenser microphone Fix: Measure DC voltage between pins 2 and 1 and between pins 3 and 1 at the microphone end of the cable. Both should read approximately +48 V DC if phantom is applied correctly. If voltage is absent on one pin, that conductor has an open circuit in the cable.
AES/EBU digital audio has high error rate or fails at longer cable lengths: Cause: Standard microphone cable used instead of 110 ohm AES/EBU cable, causing impedance mismatch and signal degradation Fix: Replace the cable with a 110 ohm balanced digital cable. For very long runs, consider an AES/EBU signal regenerator or distribution amplifier at intermediate points.
Intermittent noise or crackling when the cable is moved: Cause: Cold or cracked solder joint at a connector, or damaged conductor inside the cable from repeated flexing Fix: Flex the cable while monitoring the signal. Open both connectors and inspect solder joints — look for dull, cracked, or partially attached joints. Re-solder suspect joints. If the fault is in the cable body rather than a connector, identify the fault location by flexing systematically and replace the damaged section.

Frequently asked questions

Why is it called a balanced connection?

The circuit is balanced because both signal conductors (pins 2 and 3) are driven to the same impedance relative to ground, and carry equal-amplitude but opposite-polarity copies of the audio signal. This symmetry is what allows the differential amplifier at the far end to reject common-mode noise picked up by the cable, leaving only the audio signal.

What does CMRR mean and why does it matter for XLR cables?

CMRR stands for Common Mode Rejection Ratio — the ability of a differential input amplifier to reject signals that appear identically on both inputs. A high CMRR (typically 60–80 dB in professional equipment) means that interference picked up by the cable appears at the differential input as common-mode and is attenuated by 60–80 dB before reaching the audio path. Poor cable construction (unequal conductor capacitance) degrades CMRR.

What is the difference between XLR3, XLR5, and XLR7?

XLR3 (three-pin) is the standard for mono balanced audio. XLR5 (five-pin) is used for stereo balanced audio (two balanced channels in one connector) and for intercom headset connections. XLR7 and other multi-pin variants exist for specialised applications. The three-pin pinout (ground, hot, cold) remains consistent across all variants for the audio channels.

Can star-quad cable improve noise rejection compared to standard two-conductor cable?

Yes, significantly. Star-quad cable has four inner conductors arranged in a quad with opposite pairs connected together at each end. This geometry results in magnetic fields from opposite conductors cancelling each other out, reducing susceptibility to magnetically-induced interference by up to 20–30 dB compared to conventional two-conductor cable — particularly valuable in environments near power wiring, motors, or lighting dimmers.

Is it safe to plug a dynamic microphone into a phantom-powered XLR input?

Yes, for correctly designed dynamic (moving-coil) microphones with balanced outputs. Phantom power appears equally on pins 2 and 3 relative to pin 1; since a balanced dynamic microphone presents a transformer or differential output, the equal voltage on both signal conductors produces no net current through the microphone element. However, unbalanced dynamic microphones with pin 3 tied to pin 1 will experience a voltage differential and may be damaged — always check the microphone's compatibility before applying phantom.