Ainostone AS0409-BLK-US1
Ainostone Bluetooth Transmitter Receiver User Manual
Model: AS0409-BLK-US1
Product Overview
The Ainostone Bluetooth Transmitter Receiver is a versatile 3-in-1 audio adapter designed to enhance your audio experience. It functions as a Bluetooth transmitter, a Bluetooth receiver, and supports a bypass mode for direct audio connection. Featuring Bluetooth 5.3 technology, dual antennas for extended range, an LCD display, and multiple connectivity options (3.5mm Aux, Optical, RCA), this device allows you to wirelessly transmit audio from non-Bluetooth sources to Bluetooth headphones or speakers, or receive audio from Bluetooth devices to wired audio systems.

Image: The Ainostone Bluetooth Transmitter Receiver unit, showing its compact design, dual antennas, LCD screen, control knob, and included audio cables (3.5mm Aux, Optical, RCA).
Safety Information
Please read and understand the following safety guidelines before operating the device:
- Always use the provided power adapter to power the device. Using an unapproved power adapter or power bank may damage the device and void the warranty.
- Disconnect the power adapter from the power source when the device is not in use for extended periods.
- Do not expose the device to water, moisture, or extreme temperatures.
- Do not attempt to disassemble or repair the device yourself. Refer all servicing to qualified personnel.
Package Contents
Verify that all items are present in the package:
- Ainostone Bluetooth Transmitter Receiver Unit
- Power Adapter
- 3.5mm Audio Cable
- RCA Audio Cable
- Optical Audio Cable
- User Manual (this document)
Device Layout and Controls

Image: Front view of the device, highlighting the LCD display and control buttons. The display shows "Searching..." and volume level.

Image: Rear view of the device, illustrating the various input and output ports: DC In, AUX RX Output, Optical In, Optical Out, and AUX TX Input.
Controls:
- Power Button: Press and hold to turn on/off. Short press to switch modes (TX/RX/Bypass).
- Bluetooth Button: Short press to enter pairing mode. Long press to clear paired devices.
- Mode Switch Button: Toggles between Transmitter (TX) and Receiver (RX) modes.
- Reset Button: Resets the device to factory settings.
- Multi-function Knob: Rotate to adjust volume. Press to play/pause audio.
Setup and Connection
Powering On:
- Connect the provided power adapter to the DC IN port on the device.
- Plug the power adapter into a wall outlet.
- Press and hold the Power button (⏻) to turn on the device. The LCD screen will illuminate.
Transmitter (TX) Mode Setup:
Use TX mode to wirelessly transmit audio from non-Bluetooth devices (e.g., TV, PC, MP3 player) to Bluetooth headphones or speakers.

Image: Diagram illustrating the setup for Transmitter (TX) mode, showing audio sources like TV, PC, and MP3 players connecting to the device via 3.5mm Aux, Optical, or RCA, and then wirelessly transmitting to Bluetooth headphones, soundbars, or speakers.
- Ensure the device is in TX mode. If not, short press the Mode Switch button. The LCD will display "TX".
- Connect the audio source (e.g., TV, PC) to the device's TX Input port using the appropriate cable (3.5mm Aux, Optical, or RCA).
- Put your Bluetooth headphones or speaker into pairing mode.
- The device will automatically search for nearby Bluetooth devices. The LCD screen will show "Searching...".
- Once your device appears on the LCD, use the Multi-function Knob to select it and press the knob to confirm pairing.
- For optical connection with a TV, ensure your TV's audio output is set to PCM. (Refer to your TV's manual for specific settings).

Image: A television screen displaying audio output settings, with the "Optical" option highlighted and "PCM" selected, indicating the required setting for optical audio transmission.
Receiver (RX) Mode Setup:
Use RX mode to receive audio from Bluetooth-enabled devices (e.g., smartphone, tablet, laptop) and output it to non-Bluetooth wired speakers or home stereo systems.

Image: Diagram illustrating the setup for Receiver (RX) mode, showing Bluetooth sources like mobile phones, tablets, and laptops wirelessly connecting to the device, which then outputs audio to wired headphones, soundbars, or home stereo systems via 3.5mm Aux, Optical, or RCA.
- Ensure the device is in RX mode. If not, short press the Mode Switch button. The LCD will display "RX".
- Connect your wired speakers, headphones, or home stereo system to the device's RX Output port using the appropriate cable (3.5mm Aux, Optical, or RCA).
- Enable Bluetooth on your smartphone, tablet, or laptop and search for "Ainostone AS0409-BLK-US1" (or similar name displayed on the LCD).
- Select the device to pair. Once connected, audio from your Bluetooth device will play through your wired audio system.
Bypass Mode Setup:
Bypass mode allows direct audio pass-through when the Bluetooth function is not needed, ensuring your wired audio system remains connected without re-cabling.

Image: Diagram illustrating the setup for Bypass mode, showing audio sources like TV, laptop, or PC directly connected to the device, which then passes the audio through to wired speakers or home stereo systems without Bluetooth processing.
- Ensure the device is in Bypass mode. Short press the Power button until the LCD displays "Bypass".
- Connect your audio source (e.g., TV, PC) to the device's TX Input port.
- Connect your wired speakers or home stereo system to the device's RX Output port.
- Audio will pass directly from the source to your speakers without Bluetooth processing.
Operating Instructions
Dual Device Connection (TX Mode):
The device supports connecting to two Bluetooth headphones or speakers simultaneously in TX mode.

Image: Two individuals are shown comfortably watching TV, each wearing Bluetooth headphones, demonstrating the dual pairing capability of the device for shared audio experience.
- Connect the first Bluetooth headphone/speaker as described in the TX Mode Setup.
- Once the first device is connected, put the second Bluetooth headphone/speaker into pairing mode.
- Short press the Bluetooth button on the Ainostone device to search for the second device.
- Select the second device from the LCD list and confirm pairing.
- Both devices will now receive audio simultaneously.
Volume Control:
Rotate the Multi-function Knob clockwise to increase volume and counter-clockwise to decrease volume. The volume level will be displayed on the LCD screen.
Play/Pause:
Press the Multi-function Knob to play or pause audio playback.
Clearing Paired Devices:
To clear all previously paired Bluetooth devices, long press the Bluetooth button until the LCD indicates that the pairing list has been cleared.
Automatic Reconnection:
The device will automatically attempt to reconnect with the last paired device(s) when powered on and within range.
Maintenance
- Cleaning: Use a soft, dry cloth to clean the device. Do not use liquid cleaners or aerosol sprays.
- Storage: Store the device in a cool, dry place away from direct sunlight and extreme temperatures when not in use for extended periods.
- Antennas: Handle the dual antennas with care to avoid bending or breaking them. Ensure they are securely attached for optimal performance.
Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| No power/Device won't turn on. | Power adapter not connected or faulty. | Ensure the power adapter is securely connected to the device and a working power outlet. Use only the provided power adapter. |
| Cannot pair with Bluetooth device. | Device not in pairing mode; Bluetooth device too far; Interference; Previously paired device interfering. | Ensure the Ainostone device is in the correct TX/RX mode and pairing mode. Move devices closer. Clear previously paired devices by long pressing the Bluetooth button. Restart both devices. |
| No audio output/input. | Incorrect cable connection; Wrong mode selected; TV audio settings (for optical). | Verify all audio cables are correctly connected to the appropriate TX Input/RX Output ports. Ensure the device is in the correct TX/RX/Bypass mode. For optical connection, set TV audio output to PCM. |
| Audio quality is poor or intermittent. | Distance too far; Obstructions; Interference from other wireless devices. | Reduce the distance between the Ainostone device and the paired Bluetooth device. Remove any obstructions. Move away from other strong wireless signals (e.g., Wi-Fi routers, microwaves). |
| Cannot connect to two headphones simultaneously. | Second device not in pairing mode; Pairing procedure not followed correctly. | Ensure the first device is connected, then put the second device into pairing mode and initiate search on the Ainostone device. Follow the dual device connection steps carefully. |
Specifications
| Feature | Detail |
|---|---|
| Model Number | AS0409-BLK-US1 |
| Bluetooth Version | 5.3 |
| Operating Modes | Transmitter (TX), Receiver (RX), Bypass |
| Audio Inputs | 3.5mm Aux, Optical, RCA |
| Audio Outputs | 3.5mm Aux, Optical, RCA |
| Display | 1.8-inch LCD |
| Dual Connection | Supports 2 headphones/speakers simultaneously in TX mode |
| Antennas | Dual External Antennas |
| Product Dimensions | 4.57 x 1.53 x 5.43 inches |
| Item Weight | 6.3 ounces |
| Material | Acrylonitrile Butadiene Styrene (ABS) |
Warranty and Support
For warranty information and technical support, please contact Ainostone customer service. Details can typically be found on the product packaging or the official Ainostone website.
Manufacturer: Ainostone
ASIN: B0DFLJYHFH
Date First Available: November 13, 2024
Ask a question about this manual
Ask about setup, troubleshooting, compatibility, parts, safety, or missing instructions. Manuals+ will review the question and use this page’s manual context to help answer it.