Quick Answer: Mini XLR keeps the standard XLR contact logic in a shell roughly 10 mm across, with a push-button latch instead of a ring. The 3-pin version (TA3) is a true balanced audio connector: pin 1 shield, pin 2 hot, pin 3 cold, same as a full-size XLR. The 4-pin version (TA4) is normally an unbalanced lavalier or headset input on a wireless bodypack, where one pin carries bias voltage for the capsule and one may carry a resistor code identifying the microphone. The two are not interchangeable, and 4-pin pinouts vary by brand.
The connector is mechanically simple and electrically unforgiving. Contacts are small, the solder cups take 26 to 30 AWG wire, and the shell offers little room for a poorly trimmed shield. Most failures we see are not the connector itself but a strand of shield bridging pin 1 to pin 2, or a cable wired to the wrong brand’s pinout.
What Mini XLR Is and Where It Appears
Mini XLR is a family, not a single part. The 3-pin and 4-pin versions measure about 10 to 12 mm across the coupling ring, use a spring-loaded latch released by a button, and are rated around 125 V and 1 A, fine for microphone level only. You find them on beltpacks, lavalier and headset microphones and some studio headphones. The full-size connector is covered in our XLR connector types overview.
3-Pin: A Balanced Path in a Smaller Shell
Pin assignment
Numbering follows the full-size convention: pin 1 is the shield and ground reference, pin 2 is hot, pin 3 is cold. A balanced input sums the difference between pins 2 and 3, so interference coupled equally into both conductors cancels. That only works if the pair is twisted and the shield is bonded at one end of the run, not both.
Mating and mirroring
The female carries the sockets and the male the pins, and the numbers are mirrored when you look into the mating face. Wiring a male plug by copying the female layout is the most common assembly error, and it gives a cable that is out of phase rather than dead. The latch will not pull out when a performer turns their head, which is why the 3-pin version replaces a 3.5 mm jack.
4-Pin: Lavalier and Headset Wiring
Bias and coding
An electret capsule needs a few volts of bias, typically 1.5 to 5 V through a resistor in the bodypack. A 4-pin connector lets the pack feed that bias, take the audio back and sense which microphone is attached. That sense function is usually a resistor between two pins, and the pack uses the value to set gain and refuse incompatible capsules. A wrong resistor gives wrong gain, not silence.
Brands do not interchange
The four contacts sit in the same shell, but the function of each differs between manufacturers. Two packs that both accept a 4-pin mini XLR can still apply bias to the audio line of the other brand’s microphone, which gives distortion, a dead capsule or a damaged electret. Confirm pin functions from the bodypack manual. Balanced wiring is set out in our XLR plug connections reference.
| Type | Contacts | Typical use | Signal |
|---|
| TA3F | 3, sockets | Beltpack input, headphone lead | Balanced, mic or line |
| TA3M | 3, pins | Cable end into a device input | Balanced, mic or line |
| TA4F | 4, sockets | Lavalier and headset microphone | Unbalanced plus bias |
| TA4M | 4, pins | Bodypack output, panel mount | Unbalanced plus bias |
Assembly Notes That Decide Reliability
Strip about 2 mm, tin the strand, and keep the shield short enough that it cannot fold across pin 2. Solder cup spacing is under 1 mm on some versions, so a fine tip and 0.5 mm solder are not optional. Clamp the cable in the strain relief before soldering. Use two-conductor shielded cable for 3-pin balanced runs; unscreened cable works for a 4-pin lavalier over 1 m but picks up hum near dimmers.
Practical Scenarios
- Replacing a lavalier cable: match the bodypack brand and confirm bias and audio pins with a meter. An adapter that only fits mechanically can put 5 V across the capsule output.
- Headphone lead with a 3-pin mini XLR: wire pin 1 to ground, pins 2 and 3 to left and right, and check which side the amplifier treats as common.
- Panel connector that keeps loosening: use the panel-mount version with the supplied nut and a locking washer, and leave a service loop so the joints take no load.
- Mixing mini XLR and jack gear: keep a short adapter lead rather than modifying the device. The level differences behind TRS and XLR cables matter more than shell size.
FAQ
Is mini XLR the same as a 3.5 mm jack?
No. They are different connectors with different contacts and different signal handling. A 3-pin mini XLR can carry a balanced signal with a shield; a 3.5 mm TRS is usually unbalanced stereo or mono. Adapter leads exist, but they cannot make an unbalanced output balanced.
Can I plug a 4-pin lavalier into a 3-pin input?
Not directly, and not with a passive adapter. The 4-pin capsule needs bias that the 3-pin input does not supply on the same contacts, and the pin functions do not line up. Use the bodypack the microphone was made for, or a converter designed for that specific brand pair.
How many mating cycles does a mini XLR latch survive?
Manufacturers typically rate the latch in the low thousands of cycles, which is a rule of thumb rather than a fixed standard. In rental use the latch spring is the first part to weaken, and a plug that no longer clicks should be replaced before it unplugs mid-performance.
