BK-402A Overview and Use Cases

What Is the BK-402A?

The OREI BK-402A is a 40Gbps 4x2 HDMI matrix with audio extraction. It allows you to connect up to four HDMI source devices and route them to two HDMI displays.

Unlike a basic HDMI switch, the BK-402A can send different HDMI sources to different displays at the same time. For example, Output 1 can show a Blu-ray player while Output 2 shows a PC or TV box.

The BK-402A supports HDMI 2.1 and HDCP 2.3, with video resolutions up to 8K@60Hz 4:2:0 10-bit, 8K@30Hz 4:4:4 10-bit, and 4K@120Hz 4:4:4 10-bit. It also supports VRR, ALLM, FVA, 8K to 4K downscaling, 8K/4K to 1080p downscaling, audio extraction through Optical and 3.5mm outputs, and eARC support between Input 1 and Output 1. 

The BK-402A is useful for home theater, gaming, education, conference rooms, professional AV setups, and installations where multiple source devices need to be shared between two displays.

IMPORTANT — BK-402A Is a Matrix, Not a Simple Splitter

The BK-402A is a 4-input, 2-output HDMI matrix.

This means it can route any of the four HDMI inputs to either HDMI output.

For example:

• Output 1 can show Input 1 
• Output 2 can show Input 3 

Both outputs can also show the same input if needed.

This is different from a basic splitter, which only duplicates one source to multiple displays.

IMPORTANT — BK-402A Does Not Create Extended Dual Displays for Computers

The BK-402A is not a computer docking station or KVM switch.

It cannot take two computers and extend them across two displays like a dual-monitor workstation.

The manual specifically notes that you cannot connect two displays and two computers to this matrix to extend displays.

Use this product for HDMI source routing, not for creating extended desktop displays from computers.

IMPORTANT — eARC Works Between Output 1 and Input 1

The BK-402A supports eARC between OUT 1 and INPUT 1.

When eARC is turned on:

• OUT 1 connects to an ARC/eARC TV 
• INPUT 1 connects to an ARC/eARC soundbar 
• The soundbar receives audio returned from the TV through OUT 1 

This is useful when you want TV app audio or TV audio to play through an ARC/eARC soundbar.

If your TV supports eARC/ARC but the soundbar only supports ARC, the manual recommends turning off eARC in the TV settings.

IMPORTANT — Input 1 Changes Function When eARC Is Enabled

When eARC is turned off, INPUT 1 works like a normal HDMI source input.

When eARC is turned on, INPUT 1 is used for connecting an ARC/eARC soundbar to receive audio from OUT 1.

Because of this, customers should not expect INPUT 1 to behave as a normal source input while eARC mode is being used for a soundbar.

IMPORTANT — Optical and 3.5mm Outputs Are Muted When eARC Is On

The BK-402A includes Optical and 3.5mm analog audio outputs.

However, when eARC is turned on, the manual notes that both the Optical and L/R analog audio outputs are muted.

If a customer wants to use Optical or 3.5mm audio extraction, eARC should be turned off.

IMPORTANT — Audio Output Format Limits

The BK-402A supports HDMI audio pass-through and audio de-embedding, but each output has different format support.

If using the 3.5mm output, set the source audio to PCM or Stereo.

If using Optical, use PCM stereo, Dolby Digital, or DTS 5.1 depending on what the connected soundbar, AVR, or amplifier supports.

IMPORTANT — 8K and 4K@120Hz Require Compatible HDMI Equipment

To use 8K@60Hz, 8K@30Hz, or 4K@120Hz, every part of the setup must support the required resolution and bandwidth.

This includes:

• HDMI source device 
• HDMI display 
• HDMI cables 
• Source device video settings 

For 8K@60Hz, use Ultra High Speed HDMI 2.1 cables. The manual recommends up to 3m / 10ft for 8K60 signals.

If there is no video, flickering, or unstable signal, try shorter HDMI cables, check that the correct output LEDs are lit, and lower the resolution from the source device.

Ports and Panel Layout

Step-by-Step Setup

1. Connect the included 5V/2A power adapter to the DC 5V port on the BK-402A. 
2. Connect your HDMI source devices to HDMI INPUT 1, INPUT 2, INPUT 3, and INPUT 4. 
   Examples include a PC, DVD player, Blu-ray player, gaming console, streaming device, or TV box. 
3. Connect HDMI OUT 1 to your first TV, monitor, or projector. 
4. Connect HDMI OUT 2 to your second TV, monitor, or projector. 
5. If using Optical or 3.5mm audio extraction, connect your audio device to the Optical or L/R output. 
6. Turn on the source devices, displays, and BK-402A. 
7. Use the OUT 1 and OUT 2 buttons on the front panel or the included remote to select which input appears on each output. 
8. Set the CONFIG DIP switch based on whether you want matrix mode, splitter mode, pass-through, or scaler mode. 
9. Set the EDID DIP switch based on the video and audio format needed for your setup. 
10. If using eARC, connect OUT 1 to an ARC/eARC TV and connect INPUT 1 to an ARC/eARC soundbar, then turn on eARC. 

HDMI Cable Requirement — Critical

For best performance, use the correct HDMI cable based on the resolution being used.

The manual also recommends using Premium High Speed HDMI cables.

Poor-quality or longer HDMI cables may cause:

• No video output 
• Flickering 
• Black screen 
• Audio dropouts 
• Resolution issues 
• eARC communication issues 
• HDR or VRR not working properly 

Understanding Matrix Mode and Splitter Mode

The BK-402A supports both matrix-style routing and splitter-style routing.

Matrix Mode

Matrix mode allows Output 1 and Output 2 to show different HDMI inputs.

Example:

Use matrix mode when two displays need to show different source devices.

Splitter Mode

Splitter mode is used when you want the same source routed to both outputs.

Use splitter mode when both displays should show the same HDMI source.

CONFIG DIP Switch Settings

The CONFIG DIP switch controls the working mode of the matrix.

Use scaler mode when Output 2 is connected to a lower-resolution display.

For example, if Output 1 is connected to an 8K TV and Output 2 is connected to a 4K TV, use OUT 2 scaler mode for 8K to 4K.

EDID DIP Switch Settings

The BK-402A includes EDID DIP switch settings to help control what video and audio format the source devices output.

Use 2CH PCM modes when using the 3.5mm analog output.

Use 5.1CH modes when using Optical with a Dolby/DTS-capable audio system.

Use 7.1CH / HD modes when using HDMI audio with a compatible AVR or sound system.

Understanding eARC Mode

The BK-402A supports eARC between OUT 1 and INPUT 1.

When eARC Is Off

When eARC is turned off:

• INPUT 1 works as a normal HDMI input 
• Optical output can be used 
• 3.5mm L/R output can be used 
• Source audio can be extracted through the audio outputs 

When eARC Is On

When eARC is turned on:

• OUT 1 should connect to an ARC/eARC TV 
• INPUT 1 should connect to an ARC/eARC soundbar 
• Audio returned from the TV can play through the soundbar 
• Optical and L/R outputs are muted 
• INPUT 1 is no longer used as a normal HDMI source input 

Understanding Audio Extraction

The BK-402A can extract audio from HDMI sources when eARC is turned off.

For 3.5mm analog audio, set the source to LPCM 2.0 / PCM / Stereo.

For Optical audio, use LPCM, Dolby, or DTS 5.1 depending on the connected audio device.

Understanding the IR Remote

The included remote can control the main functions of the BK-402A.

What Source Devices Is the BK-402A Compatible With?

The OREI BK-402A is compatible with HDMI source devices such as:

• PCs 
• Gaming consoles 
• Blu-ray players 
• DVD players 
• Streaming devices 
• TV boxes 
• Cable boxes 
• Satellite receivers 
• Media players 
• Set-top boxes 

For 8K@60Hz, 8K@30Hz, 4K@120Hz, VRR, ALLM, or FVA, the source device, HDMI cable, and display must all support the selected format.

What Displays Is the BK-402A Compatible With?

The BK-402A can connect to two HDMI displays such as:

• TVs 
• Monitors 
• Projectors 
• Gaming monitors 
• Commercial displays 

For 8K output, the connected display must support 8K input.

For 4K@120Hz output, the connected display must support 4K@120Hz input.

If using eARC, Output 1 should be connected to a TV with ARC/eARC support.

What Audio Devices Is the BK-402A Compatible With?

The BK-402A can work with audio devices such as:

• ARC/eARC soundbars connected to INPUT 1 when eARC is enabled 
• Optical soundbars 
• AVRs 
• Amplifiers 
• Powered speakers 
• 2.0 speaker systems 
• Stereo audio systems 

For ARC/eARC soundbar use, connect the TV to OUT 1 and the soundbar to INPUT 1.

For Optical or 3.5mm audio extraction, turn eARC off.

Frequently Asked Questions

Q: What is the OREI BK-402A used for? 
A: The BK-402A is used to connect up to four HDMI source devices to two HDMI displays. It can route different sources to different displays and also extract audio through Optical or 3.5mm outputs.

Q: Is the BK-402A a splitter? 
A: It can be used in splitter mode, but it is primarily a 4x2 HDMI matrix. In matrix mode, each output can show a different input source.

Q: Can Output 1 and Output 2 show different sources? 
A: Yes. In matrix mode, Output 1 and Output 2 can show different HDMI sources.

Q: Can both outputs show the same source? 
A: Yes. Use splitter mode or select the same input for both outputs.

Q: Can I use this to extend two computers across two displays? 
A: No. The manual states that connecting two displays and two computers to the matrix to extend displays is not possible.

Q: Does the BK-402A support 8K? 
A: Yes. It supports up to 8K@60Hz 4:2:0 10-bit and 8K@30Hz 4:4:4 10-bit when the source, display, and cables support it.

Q: Does the BK-402A support 4K@120Hz? 
A: Yes. It supports 4K@120Hz 4:4:4 10-bit when the connected equipment supports it.

Q: Does the BK-402A support VRR and ALLM? 
A: Yes. It supports VRR, ALLM, and FVA when the source and display also support those features.

Q: Does the BK-402A support downscaling? 
A: Yes. It supports 8K to 4K downscaling and 8K/4K to 1080p downscaling for Output 2 using the CONFIG DIP switch.

Q: Does the BK-402A have audio extraction? 
A: Yes. It has Optical and 3.5mm L/R audio extraction outputs.

Q: Why is my Optical or 3.5mm output muted? 
A: Optical and L/R outputs are muted when eARC is turned on. Turn eARC off to use those audio outputs.

Q: What audio does the 3.5mm output support? 
A: The 3.5mm analog output supports LPCM 2.0CH only. Set the source to PCM or Stereo.

Q: What audio does the Optical output support? 
A: The Optical output supports LPCM, Dolby, and DTS 5.1CH.

Q: Can I connect an ARC/eARC soundbar? 
A: Yes. Connect the ARC/eARC TV to OUT 1 and connect the ARC/eARC soundbar to INPUT 1, then turn on eARC.

Q: Can INPUT 1 be used as a normal HDMI input? 
A: Yes, when eARC is turned off. When eARC is turned on, INPUT 1 is used for the ARC/eARC soundbar connection.

Q: Can I use a capture card with the BK-402A? 
A: No. The manual states that a capture card cannot be used due to HDCP encryption on the outputs.

Q: What HDMI cable length should I use? 
A: The manual recommends high-quality HDMI cables under 30 feet. For 8K60, the recommended length is 3m / 10ft.

Q: What should I do if there is no video output? 
A: Check if the corresponding output LEDs are lighting up, confirm all HDMI cables are connected and working, and try changing the HDMI cables.

Q: Can the BK-402A stay powered on continuously? 
A: Yes, it can stay running continuously, but it is recommended to turn it off when not in use.