How to Use a 3.5mm to RJ45 Adapter for Audio Over Cat5

By Innov8 Wholesale Ltd | Published: 2026-10-22

Category: How-to Guides

Learn how to send 3.5mm audio over Cat5, Cat5e, or Cat6 cable using a 3.5mm TRRS to RJ45 adapter. Step-by-step wiring, connection, and testing tips.

Quick Answer

To send 3.5mm audio over Cat5, connect a 3.5mm TRRS to RJ45 adapter to your source, run a standard network cable to the destination, and use a matching adapter on the receiving end.

Why Use Cat5 for Audio Runs?

Standard 3.5mm cables can suffer from signal loss and interference over long distances. Twisted-pair cabling like Cat5, Cat5e, or Cat6 is designed to reject noise and can carry audio reliably over much longer runs, making it ideal for whole-home audio or commercial installations.

A 3.5mm to RJ45 adapter lets you tap into that existing network infrastructure. You don't need to pull new cable—just use the spare pairs in a data run or dedicate a line to audio.

What to Check Before You Start

Confirm that your source and destination devices use a 3.5mm TRRS (4-pole) connection. TRRS carries both left and right audio channels plus a common ground, which is what the adapter expects. If your device uses TRS (3-pole), you'll need a different adapter.

Also verify that the network cable you plan to use is straight-through (pin 1 to pin 1, etc.), not crossover. Most modern cables are straight-through, but it's worth a quick check if you have a custom-made cable.

Step-by-Step: Connect 3.5mm Audio Over Cat5

Identify Your Source and Destination: Determine which device has the 3.5mm audio output (source) and which has the input (destination). Both must use a TRRS 4-pole jack for this adapter to work correctly. Check the device specs or look for a 4-pole plug icon on the jack.
Connect the Source Adapter: Plug the 3.5mm male end of a TRRS male to RJ45 adapter into the source device's headphone or audio out port. Ensure it clicks fully into place. If the connection feels loose, try a different adapter or port—loose connections cause intermittent audio.
Run the Cat5 Cable: Connect one end of a straight-through Cat5, Cat5e, or Cat6 cable into the RJ45 socket of the source adapter. Route the cable to the destination, avoiding sharp bends or running alongside high-voltage power lines. Keep the cable away from power cables to minimize hum or interference.
Attach the Destination Adapter: Plug the other end of the network cable into a TRRS female to RJ45 adapter at the destination. Then connect a standard 3.5mm cable from that adapter to your speaker, amplifier, or other audio input. Make sure the RJ45 connectors click in—an unseated connector is the most common cause of failure.
Test the Signal: Play audio from the source and listen at the destination. If there's no sound, check each connection, swap the network cable with a known-good one, and verify the source volume is up. If audio is distorted, the cable may be too long or the source output level too high—reduce volume or use a shorter run.

Adapters That Make It Work

3.5mm TRRS Female to RJ45 Female Audio Adapter Cable 0.2m – Audio over Cat5: This 3.5mm TRRS female to RJ45 female adapter converts a 4-pole AUX connection to an RJ45 socket, allowing audio distribution through twisted pair cabling. Use this adapter on the receiving end to connect a standard 3.5mm speaker or amplifier to the Cat5 run.
3.5mm TRRS Female to RJ45 Female Audio Adapter Cable 0.2m – Audio over Cat5
3.5mm TRRS 4 Pole Male to RJ45 Female Audio Adapter Cable 0.2m: This 3.5mm TRRS male to RJ45 female adapter converts a 3.5mm audio signal to an RJ45 socket for transmission over Cat5, Cat5e, or Cat6 UTP cabling. Plug this directly into your phone, laptop, or other 3.5mm source to feed audio into the network cable.
3.5mm TRRS 4 Pole Male to RJ45 Female Audio Adapter Cable 0.2m