How to Connect Dry Pair to XLR: A Practical A2 Guide
Dry pair is old infrastructure, but sometimes it is the only path left between the truck and the field. Here is how I use a known, inactive pair for balanced audio, phantom-powered microphones, RTS intercom, and RTS IFB.
Treat every venue pair as live until you prove otherwise. Identify both ends, verify continuity, and measure between the conductors and from each conductor to ground. Do not connect production equipment to an unknown or active circuit.
Quick answer: one balanced audio channel
- XLR Pin 2 → striped conductor, called Tip in this guide
- XLR Pin 3 → solid conductor, called Ring in this guide
Keep Pins 2 and 3 on the same twisted pair. A two-wire dry pair has no conductor for XLR Pin 1, so this is not a universal substitute for an XLR cable. Use it only with a known balanced source and input that can operate without a separate shield connection.
Dry Pair Basics
Tip and Ring are telephone labels, not audio polarity. In this guide, the striped conductor is Tip and the solid conductor is Ring. The convention matters less than keeping both conductors of each twisted pair together.
| Pair | Tip / Striped Conductor | Ring / Solid Conductor |
|---|---|---|
| Blue | Blue/White | Blue |
| Orange | Orange/White | Orange |
| Green | Green/White | Green |
| Brown | Brown/White | Brown |
Telephone cables continue beyond these four colors using a 25-pair color code. See the A2Sound Telephone Wire Color Code guide for the complete sequence.
XLR adapters with screw terminals or binding posts make temporary dry-pair connections without sacrificing a standard XLR cable.
American Recorder
SCRTM-XLR3-F female adapter
SCRTM-XLR3-M male adapter
Sescom
IL-XLR-POSTS, SES-MKP-21, and SES-MKP-23 binding-post adapters
Balanced Dynamic Mic or Line-Level Audio
One balanced dynamic mic or line-level feed uses one twisted pair. Connect XLR Pin 2 to the striped conductor and Pin 3 to the solid conductor.
| XLR Pin | Function | Dry-Pair Conductor | CAT5 Example |
|---|---|---|---|
| 1 | Shield / Ground | Unused* | Unused* |
| 2 | Positive Phase | Tip / Striped | Blue/White |
| 3 | Negative Phase | Ring / Solid | Blue |
*Pin 1 is unavailable on a two-conductor, unshielded pair. This method is for a known transformer-balanced or electronically balanced source and input that can work without a separate shield conductor. If the grounding is unknown or hum is present, use transformer isolation (such as an IL19) and test before connecting the truck.
Phantom-Powered Microphone
A phantom-powered mic needs a return path for XLR Pin 1. Keep Pins 2 and 3 on one intact pair, then tie both conductors of a second pair together for Pin 1 at each end.
Use this only on dedicated wiring that you have traced end to end. Confirm pin-to-pin continuity, no shorts or shared conductors, and no unexpected voltage before applying phantom. At the microphone end, Pins 2 and 3 should measure roughly the same DC voltage to Pin 1. Verify that before connecting the mic. If the route passes through unknown equipment, do not use it for phantom power.
| XLR Pin | Function | Dry-Pair Conductor | CAT5 Example |
|---|---|---|---|
| 1 | Ground / Phantom Return | Both conductors of a second pair | Orange/White + Orange |
| 2 | Positive Phase with Phantom DC | Tip / Striped | Blue/White |
| 3 | Negative Phase with Phantom DC | Ring / Solid | Blue |
RTS Two-Channel Intercom
RTS two-wire intercom uses Pin 1 as common, Pin 2 for Channel 1 audio and DC power, and Pin 3 for Channel 2 audio. Each channel and the common travel on one pair.
| XLR Pin | Function | Dry-Pair Connection | CAT5 Example |
|---|---|---|---|
| 1 | Common | Ring conductor from Pair 1 and Pair 2 | Blue + Orange |
| 2 | Channel 1 audio and DC power | Pair 1 Tip | Blue/White |
| 3 | Channel 2 audio | Pair 2 Tip | Orange/White |
BP-325 reminder: The beltpack is powered through Channel 1. Channel 2 by itself will not power the unit.
For one-channel operation, use the Pin 1 / Pin 2 pair. For two channels, add the Pin 1 / Pin 3 pair and tie both common conductors to Pin 1.
RTS Two-Channel IFB
RTS two-channel IFB uses Pin 1 as common, Pin 2 for Channel 1 interrupt audio and power, and Pin 3 for Channel 2 non-interrupt program audio.
| XLR Pin | Function | Dry-Pair Connection | CAT5 Example |
|---|---|---|---|
| 1 | Common | Ring conductor from Pair 1 and Pair 2 | Blue + Orange |
| 2 | Channel 1 interrupt audio and DC power | Pair 1 Tip | Blue/White |
| 3 | Channel 2 non-interrupt program audio | Pair 2 Tip | Orange/White |
For interrupt audio only, use the Pin 1 / Pin 2 pair. Add the Pin 1 / Pin 3 pair when the 4030 and earset also need the non-interrupt program channel.
Field Examples
These are pair assignments, not blind recipes. Confirm the pinout of every device and verify the full path before use.
Sideline Reporter: Mic, IFB, and Two Intercom Channels
Assignment: One CAT5 carries a dynamic stick mic, one-channel IFB, and two RTS intercom channels. All four pairs are used.
At the visitor tunnel, the reporter needs a stick mic and interrupt IFB while the A2 and stage teams each need PL.
| Service | CAT5 Conductor | XLR Pin | Connection |
|---|---|---|---|
| Dynamic Stick Mic | Blue/White | 2 | Stick Mic XLR |
| Dynamic Stick Mic | Blue | 3 | Stick Mic XLR |
| IFB Interrupt / Power | Orange/White | 2 | IFB XLR |
| IFB Common | Orange | 1 | IFB XLR |
| Intercom Channel 1 — A2 PL | Green/White | 2 | Intercom Beltpack XLR |
| Intercom Common | Green | 1 | Intercom Beltpack XLR |
| Intercom Channel 2 — Stage PL | Brown/White | 3 | Intercom Beltpack XLR |
| Intercom Common | Brown | 1 | Intercom Beltpack XLR |
Notes: Use a dynamic microphone such as an MD 46, RE50, or SM58. With only Pins 1 and 2 connected to a 4030 IFB beltpack, only Channel 1 interrupt audio is available.
Sideline Interview Headset
Assignment: One CAT5 carries the dynamic headset mic, two-channel IFB, and one RTS intercom channel. All four pairs are used.
This setup supports a player walk-off interview headset and a separate A2 PL.
| Service | CAT5 Conductor | XLR Pin | Connection |
|---|---|---|---|
| Dynamic Headset Mic | Blue/White | 2 | Mic XLR |
| Dynamic Headset Mic | Blue | 3 | Mic XLR |
| IFB Interrupt / Power | Orange/White | 2 | IFB XLR |
| IFB Common | Orange | 1 | IFB XLR |
| IFB Non-Interrupt Program | Green/White | 3 | IFB XLR |
| IFB Common | Green | 1 | IFB XLR |
| Intercom Channel 1 — A2 PL | Brown/White | 2 | Intercom Beltpack XLR |
| Intercom Common | Brown | 1 | Intercom Beltpack XLR |
Notes: Use a dynamic headset microphone. Confirm the 4030 and earset routing before the show; a mono earset connection will not reproduce both IFB channels.
Four Crowd Microphones with Local Preamps
Assignment: Four local mic preamps feed four independent balanced line-level pairs in one CAT5.
Each Sound Devices MP-1 powers its microphone locally, so the CAT5 carries only line-level audio. Each pair carries one feed.
| Source | CAT5 Pair | Pin 2 | Pin 3 | Destination Label |
|---|---|---|---|---|
| MKH 416 through MP-1 | Blue | Blue/White | Blue | Crowd Mic Left 1 |
| MKH 416 through MP-1 | Orange | Orange/White | Orange | Crowd Mic Right 1 |
| MKH 416 through MP-1 | Green | Green/White | Green | Crowd Mic Left 2 |
| MKH 416 through MP-1 | Brown | Brown/White | Brown | Crowd Mic Right 2 |
Use transformer isolation when the source and destination grounding arrangements are unknown or when hum is present.
Why Stadiums Still Have Dry Pair
Long before stadiums had fiber panels and network switches, broadcasters used dedicated telephone pairs to move programs between locations and carry announcer microphones back to radio stations.
Some of that wiring is still in stadiums and arenas. A pair may run from the truck pedestal to a locker room, press area, sideline, tunnel, or replay booth. When the normal paths are gone, old copper can still get a show on the air.
