What Is the ARC-EX300-K?
The OREI ARC-EX300-K is an HDMI ARC and S/PDIF audio extender over CAT cable. It is designed to send TV audio back to a soundbar, amplifier, AVR, or multi-room audio system over a long CAT cable run.
The kit includes a Transmitter, Receiver, two USB-A to Micro USB power cables, two 5V/1A power adapters, and user manual. The Transmitter connects near the TV side, the Receiver connects near the audio system side, and a CAT6 cable connects the Transmitter and Receiver.
The ARC-EX300-K supports HDMI ARC audio extension up to 150m / 495ft at 96kHz or 90m / 295ft at 192kHz. It also supports S/PDIF audio extension up to 150m / 495ft at 96kHz. Supported audio formats include PCM 2.0ch, Dolby 5.1ch, and DTS 5.1ch. CEC pass-through is supported when HDMI ARC mode is enabled.
The ARC-EX300-K is useful when a TV is installed far away from a soundbar, AVR, amplifier, or distributed audio system and the audio needs to be sent back over a single CAT cable.
IMPORTANT — ARC-EX300-K Extends Audio Only
The ARC-EX300-K is not an HDMI video extender.
It is designed for:
| Function | Support |
| HDMI ARC audio extension | Supported |
| Optical S/PDIF audio extension | Supported |
| HDMI video extension | Not supported |
| eARC extension | Not listed |
| CEC pass-through | Supported in ARC mode |
Use this product when the goal is to send TV audio to an audio system over CAT cable.
IMPORTANT — Supports ARC Mode and S/PDIF Mode
The Transmitter includes an S/PDIF / ARC switch.
| Mode | What It Does |
| ARC Mode | Sends HDMI ARC audio from Transmitter ARC IN to Receiver ARC OUT |
| S/PDIF Mode | Sends optical audio from Transmitter S/PDIF IN to Receiver S/PDIF OUT |
Use ARC mode when the TV and sound system both support HDMI ARC.
Use S/PDIF mode when using optical audio instead of HDMI ARC.
IMPORTANT — HDMI ARC Distance Depends on Sample Rate
The ARC-EX300-K supports different ARC distances depending on the audio sample rate.
| Audio Type | Sample Rate | Maximum Distance |
| HDMI ARC Audio | 96kHz | 150m / 495ft |
| HDMI ARC Audio | 192kHz | 90m / 295ft |
| S/PDIF Audio | 96kHz | 150m / 495ft |
For longer runs, use high-quality CAT6 cable and keep the installation within the listed distance.
IMPORTANT — S/PDIF Mode Is for TVs Without ARC
For TVs without an HDMI ARC port, the ARC-EX300-K provides an independent S/PDIF audio pass-through channel.
In this setup:
- TV optical audio output connects to Transmitter S/PDIF IN
- CAT6 cable connects Transmitter to Receiver
- Receiver S/PDIF OUT connects to amplifier, AVR, speaker, or audio system
This allows optical audio to be sent over a long CAT cable run.
IMPORTANT — CEC Pass-Through Works in HDMI ARC Mode
The ARC-EX300-K supports CEC pass-through when HDMI ARC mode is enabled.
CEC can help compatible TVs and audio systems communicate over HDMI ARC.
Actual CEC behavior depends on the TV, soundbar, AVR, HDMI cable, and device settings.
IMPORTANT — Supported Audio Formats
The ARC-EX300-K supports:
| Audio Format | Support |
| PCM 2.0ch | Supported |
| Dolby 5.1ch | Supported |
| DTS 5.1ch | Supported |
| Dolby TrueHD | Not listed |
| DTS-HD Master Audio | Not listed |
| Dolby Atmos | Not listed |
| eARC formats | Not listed |
For best compatibility, set the TV audio output to PCM, Dolby 5.1, or DTS 5.1 depending on what the connected sound system supports.
IMPORTANT — Use Direct CAT Cable Connection
The ARC-EX300-K should be connected directly from CAT OUT on the Transmitter to CAT IN on the Receiver.
Do not connect the CAT cable through:
- Network switch
- Router
- Internet network
- LAN switch
- Home or office network system
The manual cautions to use UTP connectors with direct interconnection and not cross connect.
IMPORTANT — Both Units Need Power
Both the Transmitter and Receiver require power.
The package includes:
| Item | Quantity |
| USB-A to Micro USB shielded cable | 2 |
| 5V/1A power adapter | 2 |
Power requirement:
| Unit | Power |
| Transmitter | DC 5V/1A through Micro USB |
| Receiver | DC 5V/1A through Micro USB |
If either red power LED is off, check the Micro USB cable, power adapter, and outlet.
Ports and Panel Layout
| Port / Switch / Indicator | Unit | Function |
| Power LED | Transmitter | Red LED turns on when Transmitter is powered |
| S/PDIF / ARC Switch | Transmitter | Selects S/PDIF or ARC audio pass-through mode |
| CAT OUT | Transmitter | Connect CAT6 cable to Receiver CAT IN |
| S/PDIF IN | Transmitter | Connect optical audio source using Toslink cable |
| ARC IN | Transmitter | Connect to TV HDMI ARC port |
| DC 5V | Transmitter | Micro USB power input |
| Power LED | Receiver | Red LED turns on when Receiver is powered |
| CAT IN | Receiver | Connect CAT6 cable from Transmitter CAT OUT |
| S/PDIF OUT | Receiver | Connect optical audio output to amplifier or speaker |
| ARC OUT | Receiver | Connect HDMI ARC output to ARC sound system |
| DC 5V | Receiver | Micro USB power input |
Step-by-Step Setup — HDMI ARC Mode
- Set the switch on the Transmitter to ARC.
- Connect the TV HDMI ARC port to ARC IN on the Transmitter.
- Connect CAT OUT on the Transmitter to CAT IN on the Receiver using CAT6 cable.
- Connect ARC OUT on the Receiver to the HDMI ARC port on the soundbar, AVR, or audio system.
- Connect one 5V/1A power adapter to the Transmitter using the Micro USB cable.
- Connect the second 5V/1A power adapter to the Receiver using the Micro USB cable.
- Turn on HDMI ARC / CEC in the TV audio settings.
- Set the TV audio output format to PCM 2.0, Dolby 5.1, or DTS 5.1 based on the sound system.
- Test audio from the TV to the soundbar or AVR.
Step-by-Step Setup — S/PDIF Pass-Through Mode
- Set the switch on the Transmitter to S/PDIF.
- Connect the TV optical audio output to S/PDIF IN on the Transmitter using an optical Toslink cable.
- Connect CAT OUT on the Transmitter to CAT IN on the Receiver using CAT6 cable.
- Connect S/PDIF OUT on the Receiver to the amplifier, AVR, soundbar, or speaker system using an optical Toslink cable.
- Connect one 5V/1A power adapter to the Transmitter.
- Connect the second 5V/1A power adapter to the Receiver.
- Set the TV audio output to Optical / S/PDIF.
- Set the TV audio format to PCM 2.0, Dolby 5.1, or DTS 5.1 depending on the connected audio system.
- Test audio output.
CAT Cable Requirement — Critical
Use high-quality CAT6 cable.
| Signal Type | Maximum Distance |
| HDMI ARC at 96kHz | 150m / 495ft |
| HDMI ARC at 192kHz | 90m / 295ft |
| S/PDIF at 96kHz | 150m / 495ft |
Poor CAT cable may cause:
- No audio
- Audio dropouts
- ARC not working
- CEC not working
- S/PDIF not passing audio
- Intermittent sound
- Reduced transmission distance
Use direct interconnection wiring and do not cross connect.
HDMI Cable Requirement — Critical
For ARC mode, use HDMI cables that support ARC.
Poor HDMI cables may cause:
- ARC not detected
- No TV audio
- CEC not working
- Audio dropouts
- Soundbar or AVR not receiving signal
Make sure the TV is connected to its HDMI ARC port, not a standard HDMI input.
Optical Cable Requirement — Critical
For S/PDIF mode, use optical Toslink cables.
Poor or damaged optical cables may cause:
- No audio
- Intermittent audio
- Audio format issues
- S/PDIF signal not detected
Make sure the optical cable clicks securely into the S/PDIF IN and S/PDIF OUT ports.
Power Requirement — Critical
Both units require DC 5V/1A power.
| Unit | Power Requirement |
| Transmitter | DC 5V/1A Micro USB |
| Receiver | DC 5V/1A Micro USB |
If there is no audio, first confirm that the red power LED is on for both units.
Understanding the Transmitter
The Transmitter is installed near the TV or audio source side.
It has:
- ARC IN
- S/PDIF IN
- S/PDIF / ARC mode switch
- CAT OUT
- DC 5V Micro USB power input
- Power LED
The Transmitter receives either HDMI ARC audio or optical S/PDIF audio and sends it over CAT cable to the Receiver.
Understanding the Receiver
The Receiver is installed near the audio system side.
It has:
- CAT IN
- ARC OUT
- S/PDIF OUT
- DC 5V Micro USB power input
- Power LED
The Receiver outputs the audio signal to a soundbar, AVR, amplifier, or speaker system.
Understanding ARC Mode
ARC stands for Audio Return Channel.
ARC lets the TV send audio back through HDMI to a soundbar or AVR.
With the ARC-EX300-K:
| Connection | Direction |
| TV ARC port to Transmitter ARC IN | TV audio enters extender |
| Transmitter CAT OUT to Receiver CAT IN | Audio travels over CAT cable |
| Receiver ARC OUT to soundbar / AVR ARC port | Audio reaches sound system |
Use ARC mode when both the TV and audio system support HDMI ARC.
Understanding S/PDIF Mode
S/PDIF mode sends optical audio over CAT cable.
With the ARC-EX300-K:
| Connection | Direction |
| TV optical output to Transmitter S/PDIF IN | Optical audio enters extender |
| Transmitter CAT OUT to Receiver CAT IN | Audio travels over CAT cable |
| Receiver S/PDIF OUT to amplifier / speaker | Optical audio reaches audio system |
Use S/PDIF mode when the TV does not have HDMI ARC or when optical audio is preferred.
Understanding the S/PDIF / ARC Switch
The switch on the Transmitter selects which audio channel is active.
| Switch Position | Active Output |
| S/PDIF | Receiver S/PDIF OUT outputs the audio from Transmitter S/PDIF IN |
| ARC | Receiver ARC OUT outputs the HDMI ARC audio from Transmitter ARC IN |
If there is no sound, confirm the switch is set to the correct mode.
Supported Technical Specifications
| Specification | Support |
| Product Type | HDMI ARC and S/PDIF audio extender over CAT cable |
| Supported Audio Formats | PCM 2.0ch, Dolby 5.1ch, DTS 5.1ch |
| ARC Distance at 96kHz | 150m / 495ft |
| ARC Distance at 192kHz | 90m / 295ft |
| S/PDIF Distance at 96kHz | 150m / 495ft |
| CEC Pass-Through | Supported in HDMI ARC mode |
| Transmitter Inputs | S/PDIF IN, ARC IN, Micro USB power |
| Transmitter Output | CAT OUT |
| Receiver Input | CAT IN, Micro USB power |
| Receiver Outputs | S/PDIF OUT, ARC OUT |
| Power Supply | DC 5V/1A |
| Power Consumption | Transmitter 0.35W, Receiver 0.7W |
| Housing | Metal enclosure |
| Color | Black |
| Dimensions | 90mm x 72mm x 20mm |
| Weight | 175g |
| Operating Temperature | 0°C to 40°C / 32°F to 104°F |
| Storage Temperature | -20°C to 60°C / -4°F to 140°F |
| Relative Humidity | 20–90% RH, non-condensing |
| ESD Protection | ±8kV air-gap discharge, ±4kV contact discharge |
What TVs Is the ARC-EX300-K Compatible With?
The ARC-EX300-K can work with TVs that have:
- HDMI ARC output
- Optical S/PDIF output
For ARC mode, the TV must support HDMI ARC and ARC must be enabled in the TV settings.
For S/PDIF mode, the TV must have optical audio output.
What Audio Devices Is the ARC-EX300-K Compatible With?
The ARC-EX300-K can connect to audio devices such as:
- Soundbars with HDMI ARC
- AV receivers with HDMI ARC
- Amplifiers with optical input
- Speakers with optical input
- Multi-room audio systems
- Audio processors
- Distributed audio systems
The audio device must support the selected audio format.
Frequently Asked Questions
Q: What is the OREI ARC-EX300-K used for?
A: The ARC-EX300-K is used to extend HDMI ARC audio or optical S/PDIF audio from a TV to a soundbar, amplifier, AVR, speaker system, or multi-room audio system over CAT cable.
Q: Does the ARC-EX300-K extend HDMI video?
A: No. It extends HDMI ARC audio and S/PDIF audio only.
Q: Does it support HDMI ARC?
A: Yes. HDMI ARC audio extension is supported.
Q: Does it support eARC?
A: eARC is not listed for this model.
Q: Does it support optical audio?
A: Yes. It supports S/PDIF optical audio pass-through.
Q: How far can it extend HDMI ARC audio?
A: It supports ARC audio up to 150m / 495ft at 96kHz or 90m / 295ft at 192kHz.
Q: How far can it extend S/PDIF audio?
A: It supports S/PDIF audio up to 150m / 495ft at 96kHz.
Q: What audio formats are supported?
A: PCM 2.0ch, Dolby 5.1ch, and DTS 5.1ch are supported.
Q: Does it support Dolby Atmos?
A: Dolby Atmos is not listed in the manual.
Q: Does it support Dolby TrueHD or DTS-HD Master Audio?
A: No. The manual lists PCM 2.0ch, Dolby 5.1ch, and DTS 5.1ch.
Q: Does CEC pass through?
A: Yes. CEC pass-through is supported when HDMI ARC mode is enabled.
Q: What CAT cable should I use?
A: Use CAT6 cable with direct interconnection wiring.
Q: Can I connect it through a network switch?
A: No. Connect the Transmitter and Receiver directly with CAT cable.
Q: Can I cross-connect the CAT cable?
A: No. The manual cautions to use direct interconnection and not cross connect.
Q: Which port connects to the TV for ARC mode?
A: Connect the TV HDMI ARC port to ARC IN on the Transmitter.
Q: Which port connects to the soundbar or AVR in ARC mode?
A: Connect ARC OUT on the Receiver to the ARC port on the soundbar or AVR.
Q: Which port connects to the TV in S/PDIF mode?
A: Connect the TV optical output to S/PDIF IN on the Transmitter.
Q: Which port connects to the amplifier in S/PDIF mode?
A: Connect S/PDIF OUT on the Receiver to the amplifier, speaker, or audio system.
Q: How do I switch between ARC and S/PDIF?
A: Use the S/PDIF / ARC switch on the Transmitter.
Q: Do both units need power?
A: Yes. Both the Transmitter and Receiver need DC 5V/1A power.
Q: Are power adapters included?
A: Yes. The package includes two 5V/1A power adapters and two USB-A to Micro USB cables.
Q: What does the power LED mean?
A: The red power LED turns on when the unit is powered.
Q: What should I do if there is no sound in ARC mode?
A: Check that the TV is connected to ARC IN, the soundbar or AVR is connected to ARC OUT, the switch is set to ARC, HDMI ARC / CEC is enabled on the TV, and both units are powered.
Q: What should I do if there is no sound in S/PDIF mode?
A: Check that the TV optical output is connected to S/PDIF IN, the audio system is connected to S/PDIF OUT, the switch is set to S/PDIF, and both units are powered.
Q: What should I do if audio drops out?
A: Use a high-quality CAT6 cable, keep the run within the supported distance, check power on both units, and confirm the audio format is PCM 2.0, Dolby 5.1, or DTS 5.1.
Q: What should I do if CEC does not work?
A: Confirm ARC mode is selected, HDMI ARC / CEC is enabled on the TV and sound system, and use HDMI cables that support ARC.
Q: Does the ARC-EX300-K need external power?
A: Yes. Connect one included 5V/1A power adapter to the Transmitter and one to the Receiver.
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