XLR Wiring Diagrams: The Visual Reference for 3-Pin and 4-Pin Builds
Quick answer / TL;DR: Short answer: the standard 3-pin XLR wiring diagram maps pin 1 to the shield, pin 2 to the hot conductor, and pin 3 to the cold conductor – identical at both ends of a straight cable. The 4-pin diagram adds a second channel (or a control function) on pins 4 and the associated pair. Cable-to-cable diagrams map each pin across the connector, and a reversed diagram swaps the hot/cold relationship at one end. Read the diagram against the physical pins, and the build or the check is a lookup, not a guess.
A wiring diagram is the reference that turns an XLR termination from a memory task into a lookup task: the 3-pin assignment, the 4-pin stereo layout, the cable-to-cable mapping, and the straight-versus-reversed relationship are all legible in a diagram that a technician can hold next to the connector. This article is that reference, described in tables a builder can work from.
Each diagram case is laid out as a pin-to-conductor mapping, so the reference serves both the reader checking an existing cable and the builder wiring a new one.
Diagram 1 – The Standard 3-Pin
| Pin | Conductor | Color convention (varies) | Function |
|---|---|---|---|
| 1 | Shield | Braided shield / drain | Ground and noise rejection |
| 2 | Hot | Often red or the colored conductor | Signal + |
| 3 | Cold | Often the second colored conductor | Signal – |
Color conventions vary by manufacturer and region – the pin function is the standard, the color is a local habit. The diagram is read by pin function, and the actual conductor colors are matched at both ends of the build.
Diagram 2 – The 4-Pin (Stereo)
| Pin | Function | Typical stereo use |
|---|---|---|
| 1 | Shield (channel A) | Ground – channel A |
| 2 | Hot (channel A) | Left – signal A + |
| 3 | Cold (channel A) | Left – signal A – |
| 4 | Hot or second signal | Right / channel B (application-specific) |
The 4-pin stereo arrangement carries two balanced channels, but the exact assignment of the fourth pin and the second shield varies by manufacturer. The 4-pin diagram must be read against the specific device's manual – the 3-pin standard does not extend unambiguously to the fourth pin.
Diagram 3 – Cable-to-Cable (Straight)
| This end | Connector | That end | Mapping |
|---|---|---|---|
| Male pin 1 | Shield | Female pin 1 | Shield to shield |
| Male pin 2 | Hot | Female pin 2 | Hot to hot |
| Male pin 3 | Cold | Female pin 3 | Cold to cold |
A straight cable maps each pin to the same-numbered pin at the other end – 1 to 1, 2 to 2, 3 to 3. The cable-to-cable diagram is the mapping a continuity check verifies, pin by pin.
Diagram 4 – Reversed (Phase-Inverted)
| This end | Connector | That end | Mapping |
|---|---|---|---|
| Male pin 2 | Hot | Female pin 3 | Hot to cold |
| Male pin 3 | Cold | Female pin 2 | Cold to hot |
| Male pin 1 | Shield | Female pin 1 | Shield to shield |
A reversed cable swaps the hot and cold mapping between ends – pin 2 at one end meets pin 3 at the other. This is a deliberate build for correcting an external phase inversion, not the default. A reversed cable in a straight-wired expectation is the classic thin-sound error.
4-pin and multi-pin assignments vary by manufacturer and standard; the knowledge base does not provide a universal 4-pin diagram. Read the 4-pin and multi-pin cases against the specific device's manual before wiring or verifying.
Real-World Applications
The build reference
A technician wiring a batch of cables holds the 3-pin and cable-to-cable diagrams at the bench – each termination is a lookup, and the phase check at the end reads against the straight mapping.
The verification reference
A continuity check across an existing cable reads against the cable-to-cable diagram – a pin that maps to the wrong number is a crossed or reversed build, identified by the diagram rather than by symptom.
The 4-pin install
A stereo 4-pin run is verified against the device's manual and the 4-pin diagram – the fourth pin's application-specific assignment is the reason the 4-pin case is always read, never assumed.
Related reading: The pin functions these diagrams map? Read the pinout guide — blogs/news/xlr-connector-pinout
Related reading: Browse XLR cables with published wiring diagrams — collections/audio-cables
Frequently Asked Questions
What does a straight XLR wiring diagram show?
Each pin maps to the same-numbered pin at the other end – 1 to 1, 2 to 2, 3 to 3. The hot and cold relationship is aligned, which is the standard for microphones and line-level audio.
How is a reversed wiring diagram different?
A reversed diagram swaps the hot and cold mapping – pin 2 at one end maps to pin 3 at the other. It is a deliberate build for correcting a phase inversion, not the default wiring.
Is the 4-pin XLR diagram universal?
No – the 3-pin assignment is the standard, but the fourth pin's function varies by manufacturer and application. Always read the 4-pin diagram against the specific device's manual.
Can a wiring diagram replace a phase check?
No – the diagram states the intended mapping; the phase check verifies the actual cable matches it. A cable can be built to the wrong diagram, which is why the check is a separate step from the reference.
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