1. Introduction
The Airfrex SEHD is a compact Bluetooth receiver designed to transform your compatible Sennheiser HD series wired headphones into wireless headphones. This adapter provides a stable Bluetooth connection with a range of over 10 meters, ensuring clear audio transmission without electrical or static noise. Its metal aluminum casing makes it durable and portable, an ideal accessory for enhancing your listening experience.
This manual provides detailed instructions on how to set up, operate, and maintain your Airfrex SEHD Bluetooth Receiver.
Figure 1: Airfrex SEHD Bluetooth Receiver in use with Sennheiser HD599 headphones and a smartphone.
2. Package Contents
Please check the package for the following items:
- Airfrex SEHD Bluetooth Receiver
- USB Charging Cable
- User Manual (this document)
Figure 2: Airfrex SEHD Bluetooth Receiver and its packaging contents.
3. Setup and Pairing
3.1. Connecting to Headphones
- Identify the 2.5mm audio input port on your compatible Sennheiser HD series headphones.
- Insert the 2.5mm jack of the Airfrex SEHD Bluetooth Receiver firmly into the headphone's audio input port. Ensure a secure connection.
3.2. Powering On/Off
- To Power On: Press and hold the multi-function button (located on the adapter) for approximately 3 seconds until the LED indicator lights up.
- To Power Off: Press and hold the multi-function button for approximately 3 seconds until the LED indicator turns off.
3.3. Bluetooth Pairing
The Airfrex SEHD is designed for quick and automatic pairing.
- Ensure the Airfrex SEHD is powered on and in pairing mode (the LED indicator will typically flash).
- On your audio source device (e.g., smartphone, tablet, computer), enable Bluetooth and search for available devices.
- Select "Airfrex SEHD" from the list of found devices.
- Once connected, the LED indicator on the Airfrex SEHD will typically show a solid light or a slow flash. The device will automatically re-pair with the last connected device when powered on.
Figure 3: Airfrex SEHD compatibility with Sennheiser HD598, HD598Cs, HD598SE, HD595, HD599 headphones.
Figure 4: Airfrex SEHD compatibility with Sennheiser HD559, HD569, HD579, HD518, HD558 headphones.
4. Operating Instructions
4.1. Multi-function Button Controls
The single multi-function button on the Airfrex SEHD controls various functions:
- Single Press: Play/Pause audio, Answer/End a phone call.
- Double Press: Activate Bass Boost feature. Double press again to cancel Bass Boost.
- Long Press (approx. 3 seconds): Power On/Off.
4.2. LED Indicator
The LED indicator provides status information:
- Flashing LED: Pairing mode.
- Solid LED (or slow flash): Connected.
- Red LED: Low battery.
- Solid Red LED (while charging): Charging.
- LED Off (while charging): Fully charged.
Figure 5: Airfrex SEHD button controls and LED indicator functions.
5. Charging the Battery
The Airfrex SEHD has a built-in rechargeable battery. When the battery is low, the LED indicator will turn red.
- Connect the small end of the provided USB charging cable to the charging port on the Airfrex SEHD.
- Connect the larger end of the USB cable to a USB power source (e.g., computer USB port, USB wall adapter).
- The LED indicator will show a solid red light during charging.
- Once fully charged, the LED indicator will turn off.
A full charge typically provides up to 6 hours of playback time.
6. Maintenance
To ensure the longevity and optimal performance of your Airfrex SEHD Bluetooth Receiver, follow these maintenance guidelines:
- Cleaning: Use a soft, dry cloth to clean the device. Avoid using harsh chemicals or abrasive materials.
- Storage: Store the device in a cool, dry place away from direct sunlight and extreme temperatures.
- Water Exposure: This device is not waterproof. Avoid exposure to water or excessive moisture.
- Handling: Handle the device with care. Avoid dropping or subjecting it to strong impacts.
7. Troubleshooting
If you encounter issues with your Airfrex SEHD, please refer to the following troubleshooting steps:
| Problem | Possible Cause | Solution |
|---|---|---|
| Device does not power on. | Low battery. | Charge the device using the provided USB cable. |
| Cannot pair with a device. | Bluetooth not enabled on source device; device not in pairing mode; too many devices connected. | Ensure Bluetooth is on and the SEHD is flashing (pairing mode). Forget previous connections on your source device and try again. |
| No sound or poor sound quality. | Volume too low; loose connection; out of range; interference. | Check volume on both the source device and headphones. Ensure the SEHD is securely connected to headphones. Move closer to the source device (within 10m). Avoid obstacles. |
| Bass Boost not working. | Feature not activated. | Double press the multi-function button to activate Bass Boost. |
| Short battery life. | Battery not fully charged; aging battery. | Ensure the device is fully charged. Battery performance may degrade over time. |
8. Specifications
| Feature | Detail |
|---|---|
| Model | SEHD |
| Brand | Airfrex |
| Weight | 15 grams |
| Compatible Headphones | Sennheiser HD598, HD598Cs, HD598SE, HD595, HD599, HD559, HD569, HD579, HD518, HD558 |
| Compatible Devices | iPhone, iPod, iPad, iMac (any Bluetooth audio source) |
| Bluetooth Range | Over 10 meters (33 feet) |
| Battery Capacity | 120 mAh |
| Battery Life | Up to 6 hours |
| Audio Features | CSR Chipset, CD Grade Sound Quality, DSP, Bass Boost (24bit/192K), CVC Noise Cancelling Technology |
| Additional Features | Automatic Shutdown |
| Origin | China |
| UPC | 708210350419 |
Figure 6: Key features of the Airfrex SEHD Bluetooth Receiver.
