Quick answer: Standard 3-pin XLR pin out: pin 1 = shield/ground, pin 2 = hot (+), pin 3 = cold (-). 4-pin XLR adds a second pair (commonly DC power on a headset or intercom: pins 2/3 audio, pins 1/4 power in some schemes – check the device). 5-pin XLR carries two data pairs: in DMX lighting it duplicates the data pair across both, and in stereo intercom systems it carries two channels. Verify any unknown cable pin-to-pin with a multimeter’s continuity mode before trusting labels.
XLR Pin Out: 3-Pin, 4-Pin, 5-Pin Assignments on One Card
The XLR pin out looks trivial – three pins, three jobs – until a 5-pin DMX connector or a 4-pin headset plug appears on the bench, and the assumption that all XLRs are identical starts costing time. The families share a shell and a latch but not always a signal plan.
This guide gives the pin assignments for the common XLR families in one place, explains why 5-pin exists when 3-pin works, and shows how to verify an unlabelled cable with nothing but a multimeter.
The 3-Pin Standard
The version everyone meets first.
Audio Assignments
Pin 1 shield, pin 2 hot, pin 3 cold – the convention that makes every balanced audio link interchangeable. Print it once and tape it inside the equipment case; it answers half of all cable questions.
Where the Convention Wobbles
Ancient European gear wired pin 3 hot, and some old American broadcast kit differs too. Modern equipment is uniform; the exceptions live in museums and estate sales, which is exactly where multimeters earn their keep.
The Multi-Pin Families
4- and 5-pin XLRs exist for real reasons.
4-Pin: Power and Headsets
Intercom beltpacks and some headset systems use 4-pin XLR for combined audio and DC power. Assignments vary by manufacturer – some put DC on pins 1/4, others split differently – so the device manual is the authority, never the connector shape.
5-Pin: DMX and Stereo Intercom
DMX512 lighting runs on 5-pin by spec: one data pair on pins 2/3, a spare duplicate pair on pins 4/5, shield on 1. Stereo intercom systems use both pairs as two audio channels. The lesson: 5-pin is not ‘3-pin plus nothing’ – it is a different signal plan in the same shell.
Why 3-Pin DMX Cables Differ
DMX over 3-pin connectors works electrically but demands 110-ohm data cable, not audio cable. The connector being identical is exactly why mis-wired DMX rigs are common – the shell lies, the cable spec does not.
XLR pin out families at a glance
| Type | Pin 1 | Pins 2/3 | Pins 4/5 | Typical use |
|---|---|---|---|---|
| 3-pin XLR | Shield | Hot / cold audio | – | Balanced audio |
| 4-pin XLR | Varies | Audio or power | – | Intercoms, headsets (check device) |
| 5-pin DMX | Shield | Data pair A | Duplicate pair B | Lighting control |
| 5-pin stereo intercom | Shield | Channel 1 | Channel 2 | Comms systems |
Verifying an Unknown Cable
The multimeter answers what labels cannot.
Print the pin map that matters to your own stock – 3-pin audio, 5-pin DMX, 4-pin intercom, each on a line – and tape it inside the cable drawer. The card outlives every forum thread and answers the question at the moment it is asked, which is always the moment nobody has time to search.
Continuity Mapping
Continuity mode, one probe on each end’s pin 1, then 2, then 3: beeps map the cable’s actual wiring. Write the map on tape and wrap it on the cable – a ten-second test that ends the ‘is this a DMX cable or an audio cable’ argument permanently.
Bridge and Short Detection
Then check between different-numbered pins: any beep means a solder bridge or crushed cable. Shorts between pin 1 and signal pins are the silent killer of DMX rigs and the hum source in audio ones.
When the Map Disagrees With the Label
Trust the meter. Factory mislabels, previous repairs and homemade cables all exist; the pin-to-pin map is the only ground truth in the drawer.
Real-World Application Scenarios
A church lighting volunteer inherits a drawer of unlabelled 5-pin cables and spends one evening mapping each with a multimeter; three turn out to be audio cable (wrong impedance) and are retired from the DMX rack before they could corrupt a show. An intercom installer confirms a beltpack’s 4-pin scheme from the manual instead of guessing, because two manufacturers in the same rack wire power differently.
A studio engineer’s ‘mystery hum’ ends when pin-to-pin mapping reveals a homemade cable with shield soldered to pin 3 – one reflow and the rack is quiet. Each scenario is the same lesson: the pin out is a convention, and the meter is its enforcement.
A broadcast engineer keeps a laminated pin-out card in the tool case – 3-pin audio on one side, 5-pin DMX on the other – because the question ‘which pin is hot’ arrives at the worst possible moment, and the card answers it without a phone or a forum.
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Frequently Asked Questions (FAQ)
Q: What is the standard 3-pin XLR pin out?
A: Pin 1 = shield, pin 2 = hot (+), pin 3 = cold (-). This convention applies to virtually all modern balanced audio equipment.
Q: Can I use a 5-pin XLR cable for audio?
A: Only with adapters designed for the specific device, because 5-pin carries two pairs – in DMX it is duplicated data, in intercoms two channels. Never assume pin-for-pin compatibility.
Q: Is a 3-pin DMX cable the same as an audio XLR cable?
A: No. The connector matches but DMX needs 110-ohm data cable; audio cable’s different impedance causes flickering and intermittent fixtures in lighting rigs.
Q: How do I identify an unlabelled XLR cable?
A: Multimeter continuity from pin to pin across the ends maps the wiring in seconds, and cross-pin tests expose shorts. The meter beats any label.
Q: Do all XLR connectors use the same pin numbers?
A: Within the 3-pin family, yes – the convention is universal. 4-pin and 5-pin shells number pins differently by scheme, which is why the multimeter mapping habit exists.