Audio connector pinouts
The wiring for every connector in the road case, with the mistakes that cause hum and silence.
Showing all connectors.
XLR, 3-pin (balanced mic and line)
| Pin | Signal |
|---|---|
| 1 | Shield / ground |
| 2 | Hot (+) |
| 3 | Cold (−) |
"Pin 2 hot" is the standard (AES14 / IEC 60268-12). Some very old gear used pin 3 hot. Phantom power puts +48 V on pins 2 and 3 equally, relative to pin 1.
AES3 (AES/EBU digital) on XLR
| Pin | Signal |
|---|---|
| 1 | Shield / ground |
| 2 | Data |
| 3 | Data |
The data is polarity-insensitive, but the cable isn't interchangeable with mic cable on long runs: AES3 is built for 110 Ω cable. Ordinary mic cable often works on short patches and fails on long ones.
DMX512 (5-pin and 3-pin XLR)
| Pin | Signal |
|---|---|
| 1 | Common / shield |
| 2 | Data − |
| 3 | Data + |
| 4, 5 | Optional second data pair (5-pin only), usually unused |
DMX wants 120 Ω data cable and a terminator at the end of the line. Mic cable "works" until a long run starts flickering.
TRS 1/4" (balanced)
| Contact | Signal |
|---|---|
| Tip | Hot (+) |
| Ring | Cold (−) |
| Sleeve | Shield / ground |
The same plug is also used for stereo headphones (tip left, ring right, sleeve ground) and for insert cables (below). Same connector, three different jobs.
Insert cable (TRS to two TS)
| Contact on the TRS | Signal | Goes to |
|---|---|---|
| Tip | Send (out of the console) | Input of the outboard gear |
| Ring | Return (back into the console) | Output of the outboard gear |
| Sleeve | Ground | Both sleeves |
Tip-send is the most common convention, but some consoles use ring-send. If the compressor does nothing, swap the two TS plugs before blaming the gear.
TS 1/4" (unbalanced)
| Contact | Signal |
|---|---|
| Tip | Signal |
| Sleeve | Ground / shield |
Instrument cable, not speaker cable. A shielded instrument cable on an amp output has thin conductors that heat up, and an unshielded speaker cable on an instrument picks up hum.
3.5 mm (1/8") stereo, TRS
| Contact | Signal |
|---|---|
| Tip | Left |
| Ring | Right |
| Sleeve | Ground |
3.5 mm TRRS headset (CTIA)
| Contact | Signal |
|---|---|
| Tip | Left |
| Ring 1 | Right |
| Ring 2 | Ground |
| Sleeve | Microphone |
CTIA is the current standard for phones, laptops and most headsets. The older OMTP layout swaps ring 2 and the sleeve (mic and ground). If a headset sounds hollow or the mic is dead, that's the usual cause.
speakON (NL2, NL4, NL8)
| Contact | Typical use |
|---|---|
| 1+ / 1− | Full-range speaker, or the low-frequency driver when bi-amped |
| 2+ / 2− | High-frequency driver when bi-amped, or a second channel (NL4 and NL8 only) |
| 3± / 4± | Extra pairs on NL8, for tri-amp or four-way boxes |
An NL2 plug fits an NL4 socket and only uses 1+/1−. Check what a cabinet expects on 2± before plugging a bi-amp cable into a passive box's link jack.
RJ45 / EtherCON: T568A and T568B
| Pin | T568B | T568A |
|---|---|---|
| 1 | White / orange | White / green |
| 2 | Orange | Green |
| 3 | White / green | White / orange |
| 4 | Blue | Blue |
| 5 | White / blue | White / blue |
| 6 | Green | Orange |
| 7 | White / brown | White / brown |
| 8 | Brown | Brown |
Use the same standard on both ends for a normal patch cable. A or B both work, as long as they match. One of each makes a crossover cable, which modern gear usually sorts out by itself. Dante and AES67 run on ordinary gigabit Ethernet, so all four pairs matter.
DB25 analog, Tascam / AES59 (8 balanced channels)
| Channel | Hot | Cold | Ground |
|---|---|---|---|
| 1 | 24 | 12 | 25 |
| 2 | 10 | 23 | 11 |
| 3 | 21 | 9 | 22 |
| 4 | 7 | 20 | 8 |
| 5 | 18 | 6 | 19 |
| 6 | 4 | 17 | 5 |
| 7 | 15 | 3 | 16 |
| 8 | 1 | 14 | 2 |
Pin 13 is unconnected. Yamaha used a different DB25 layout on some older gear, and some AES/EBU digital interfaces use DB25 with their own (Tascam digital) layout, so check before you patch.
Field notes
- Hum after a new cable? Check whether a balanced output went into an unbalanced input with the cold leg left floating or shorted the wrong way. Pin 1 problems cause most ground hum.
- Polarity flips from a miswired adapter don't show up on a meter but cancel bass when two mics or speakers combine. A polarity tester or a quick listen with both on is worth it after a re-termination.
- Label custom cables. A cable wired for one console's inserts or one rack's DB25 layout is a trap for the next person.