BK-401A Overview and Use Cases – OREI

What Is the BK-401A?

The OREI BK-401A is an 8K@60Hz 4x1 HDMI switch with S/PDIF audio output. It allows you to connect up to four HDMI source devices to one HDMI display while also extracting digital audio through the S/PDIF output.

The BK-401A is useful for home theater, gaming, media entertainment, broadcasting, command centers, security monitoring, and professional AV setups where multiple HDMI sources need to be switched to one display.

The BK-401A supports HDMI 2.1 and HDCP 2.3, with a transmission speed of 48Gbps and video resolutions up to 8K@60Hz. It also supports 4K@120Hz, HDR10+, Dolby Vision, HLG, YUV 4:4:4, HDMI 3D, VRR, Free Sync, and G-Sync.

The BK-401A includes four HDMI inputs, one HDMI output, one S/PDIF audio output, RS-232 control, IR remote control, EDID passthrough, and a Micro USB port for firmware upgrades.

IMPORTANT — S/PDIF Audio Has Format Limitations

The BK-401A supports additional digital audio output through the S/PDIF port.

However, S/PDIF has different audio format limitations compared to HDMI. HDMI can carry higher-bandwidth audio formats, while S/PDIF is generally used for stereo PCM or compressed surround formats like Dolby Digital or DTS 5.1.

If you are not getting audio through S/PDIF, check the audio format from the source device and set the source to a format supported by your amplifier or soundbar.

HDMI Cable Requirement — Critical

For 8K@60Hz and 4K@120Hz, use high-quality Ultra High-Speed Certified HDMI 2.1 cables under 15 feet.

Ports and Panel Layout

Port / LED / Button	Location	Function
Power Indicator	Front panel	Orange indicator turns on when the device is powered
HDMI Input Indicators	Front panel	Blue indicators show which HDMI input is selected
IR Receiving Window	Front panel	Receives IR signal from the remote control
Switch Button	Front panel	Press to switch between HDMI input sources
RS-232 Port	Front panel / side panel	3-pin RS-232 port for command control
S/PDIF Output	Rear panel	Outputs digital audio signal to an amplifier, soundbar, or receiver
Micro USB	Rear panel	Used for firmware upgrade
HDMI Inputs 1–4	Rear panel	Connect HDMI source devices
HDMI Output	Rear panel	Connect to HDMI display device
DC 5V	Rear panel	Connect the included DC 5V/1A power adapter

Step-by-Step Setup

Connect the included DC 5V/1A power adapter to the BK-401A and plug it into a power outlet.
Connect your HDMI source devices to HDMI Input 1, Input 2, Input 3, and Input 4.
Examples include a DVD player, laptop, gaming console, media center, Blu-ray player, streaming device, or cable box.
Connect the HDMI Output port on the BK-401A to your TV, monitor, or projector.
If you want to use audio extraction, connect the S/PDIF output to your amplifier, soundbar, receiver, or digital audio system.
Turn on the HDMI source devices, display, and audio system.
Use the switch button, IR remote control, or RS-232 commands to select the HDMI source you want to display.

Understanding Switching Control

The BK-401A supports multiple switching control methods.

Manual Switching

Press the switch button on the device to switch between the connected HDMI input sources.

IR Remote Switching

Use the included IR remote control to switch between HDMI sources without touching the device.

RS-232 Control

The BK-401A also supports RS-232 command control using a 3-pin terminal block.

This is useful for professional AV installations, control rooms, automation systems, or commercial setups where the switch needs to be controlled by a third-party control system.

Understanding S/PDIF Audio Output

The S/PDIF output sends digital audio from the selected HDMI source to an external audio device.

Use this output when connecting to:

Audio amplifier
Soundbar with S/PDIF input
AV receiver
Digital speaker system
External audio processor

What Source Devices Is the BK-401A Compatible With?

The OREI BK-401A is compatible with HDMI source devices such as:

Blu-ray players
DVD players
Gaming consoles
Laptops
Desktop PCs
Streaming devices
Cable boxes
Satellite receivers
Media players
Media centers
Set-top boxes

For 8K@60Hz, 4K@120Hz, VRR, HDR10+, or Dolby Vision, the source device, display, and HDMI cables must all support the required format.

What Displays Is the BK-401A Compatible With?

The BK-401A can be connected to HDMI displays such as:

TVs
Monitors
Projectors
Gaming monitors
Commercial displays
Control room displays
Security monitoring displays

What Audio Devices Is the BK-401A Compatible With?

The BK-401A can send audio through S/PDIF to audio devices such as:

Soundbars
AV receivers
Amplifiers
Digital audio processors
Speaker systems with S/PDIF input

Frequently Asked Questions

Q: What is the OREI BK-401A used for?
A: The BK-401A is used to connect up to four HDMI source devices to one HDMI display while also extracting digital audio through the S/PDIF output.

Q: Does HDMI still pass audio to the TV?
A: Yes. HDMI audio can still pass through the HDMI output to the connected display.

Q: What is the RS-232 baud rate?
A: The RS-232 baud rate is 9600.

Q: Does the BK-401A need external power?
A: Yes. Connect the included DC 5V/1A power adapter to power the device.

Q: Why do I see a black screen when switching inputs?
A: This is normal. The display needs time to detect the new HDMI signal and complete the HDMI handshake. The delay can vary depending on the display, source device, resolution, refresh rate, and HDMI cables. For faster switching, you need an HDMI Switch that supports Seamless Switching.