1. Introduction
Thank you for purchasing the SANSUI F31 Multifunctional Portable Bluetooth Speaker. This device combines a powerful Bluetooth speaker with an FM radio, MP3 player, and recording capabilities, designed for both indoor and outdoor use. Please read this manual carefully to ensure proper operation and to fully enjoy all its features.
2. Package Contents
Please check the box for the following items:
- 1 x SANSUI F31 Portable Bluetooth Speaker
- 1 x User Instructions Manual
- 1 x TYPE-C Interface Charging Cable
- 1 x Hanging Rope
Note: Retail packaging is not included.
3. Product Overview
The SANSUI F31 is a compact and versatile audio device. It features an intuitive control panel, multiple connectivity options, and a durable design.

Figure 1: SANSUI F31 Portable Bluetooth Speaker (Black/Red)

Figure 2: Top view with control buttons and LED display
Video 1: SANSUI F31 Product Demonstration
4. Initial Setup
4.1 Charging the Speaker
Before first use, fully charge the speaker. Connect the provided TYPE-C charging cable to the speaker's DC 5V port and the other end to a USB power adapter (not included) or a computer USB port. The LED indicator will show charging status.
4.2 Powering On/Off
Press and hold the power button (usually marked with a power symbol) on the control panel to turn the speaker ON or OFF.
5. Operating Modes
The SANSUI F31 supports five primary playback modes:

Figure 3: Five Play Modes: Bluetooth, TF Card, USB Drive, FM Radio, Headset
5.1 Bluetooth Mode
- Turn on the speaker. It will automatically enter Bluetooth pairing mode or you can switch to Bluetooth mode using the 'M' (Mode) button.
- On your smartphone or other Bluetooth-enabled device, search for available Bluetooth devices.
- Select "SANSUI F31" from the list to pair. A confirmation sound will indicate successful pairing.
5.2 FM Radio Mode
- Switch to FM mode using the 'M' button.
- Press and hold the Play/Pause button to initiate an automatic station scan. The speaker will save all found stations.
- Use the Previous/Next track buttons to navigate between saved FM stations.
5.3 USB Drive / TF Card Playback
- Insert a USB flash drive or a TF (MicroSD) card containing MP3 audio files into the respective port.
- The speaker will automatically detect the storage device and begin playing music. If not, switch to USB or TF mode using the 'M' button.
- Use the numeric buttons (1-9) for digital song selection or the Previous/Next track buttons to skip songs.
5.4 AUX Mode
- Connect an external audio device (e.g., smartphone, MP3 player) to the speaker's AUX port using a 3.5mm audio cable (not included).
- Switch to AUX mode using the 'M' button. Audio will play from the connected device.
5.5 Headset Mode
Connect a wired headset to the speaker's headphone jack for private listening. The speaker's sound output will be redirected to the headset.

Figure 4: Connectivity Ports (TF, USB, DC 5V, AUX, Headphone)
6. Recording Function
The SANSUI F31 supports one-click recording and deletion.

Figure 5: One-Click Recording and Deletion Buttons
6.1 One-Click Recording
In USB drive or TF card music playback mode, long press the dedicated recording button (labeled with a microphone icon or '录音') to start recording. Press again to stop recording.
6.2 One-Click Deletion
To delete a recorded file, navigate to the file in USB or TF card mode. Long press the deletion button (labeled '删除') to delete the current file.
7. Hands-Free Calling
When connected via Bluetooth to a smartphone, the SANSUI F31 allows for high-definition hands-free calls thanks to its built-in microphone.

Figure 6: High-Definition Hands-Free Calling
When a call comes in, press the Play/Pause button to answer. Press again to end the call.
8. Battery and Charging
The speaker is equipped with a built-in 1800mAh polymer lithium battery, providing approximately 3-4 hours of playback time on a single charge. Use the provided TYPE-C charging cable with a DC 5V/1A-3A power source for optimal charging.

Figure 7: Charging the SANSUI F31 Speaker
9. Maintenance
- Keep the speaker dry. Avoid exposure to water or moisture.
- Clean the speaker with a soft, dry cloth. Do not use abrasive cleaners or solvents.
- Store the speaker in a cool, dry place away from direct sunlight and extreme temperatures.
- Do not attempt to disassemble or repair the speaker yourself. This will void the warranty.
10. Troubleshooting
10.1 No Power
- Ensure the battery is charged. Connect the speaker to a power source using the TYPE-C cable.
- Press and hold the power button for a few seconds to ensure it's properly turned on.
10.2 No Sound
- Check the volume level on both the speaker and the connected device.
- Ensure the correct playback mode (Bluetooth, FM, USB, TF, AUX) is selected.
- If using Bluetooth, ensure the speaker is properly paired with your device.
- If using USB/TF card, ensure the audio files are in a supported format (e.g., MP3) and the card/drive is not corrupted.
10.3 Bluetooth Disconnection
- Ensure the speaker and your device are within the effective Bluetooth range (10-20 meters).
- Check for interference from other wireless devices.
- Try unpairing and re-pairing the speaker with your device.
11. Specifications

Figure 8: SANSUI F31 Product Parameters
| Feature | Detail |
|---|---|
| Speaker Material | ABS + Iron Mesh |
| Bluetooth Version | 5.0 |
| Maximum Wireless Range | 10m - 20m |
| Horn Size | 1.75 inches |
| Rated Output Power | 2 x 5W |
| Peak Music Power Output (PMPO) | 35W |
| Impedance | 2-4 Ohm |
| Frequency Response | 100Hz - 20KHz |
| Battery Capacity | 1800mAh Polymer Lithium Battery |
| Playback Time | 3-4 hours |
| Input Power Supply | DC 5V/1A-3A (TYPE-C USB) |
| Body Size (L x W x H) | 123mm x 46mm x 71mm |
| Net Weight | Approx. 264g |
| Audio Crossover | Full-Range |
| Number of Loudspeaker Enclosures | 1 |
| Channels | 2 (2.0) |
| Control | Volume Control |
| Support APP | Yes |
| Built-in Microphone | Yes |
| Display Screen | Yes |
| Waterproof | No |
| Power Source | Battery, USB |
| Playback Function | Radio, MP3 |
| Acoustic Enclosure | HORN |
| Tweeter Type | PIEZO |
| Codecs | Apt-X HD |
| Support Apt-x | Yes |
| Charging Cable Included | Yes |
12. User Tips
- For best FM reception, ensure the speaker is placed in an open area away from obstructions.
- To maximize battery life, avoid fully draining the battery frequently. Charge it regularly.
- Experiment with different audio sources (Bluetooth, TF card, USB) to find your preferred sound quality and convenience.
- The magic colored light at the back of the body can be switched on/off for ambiance.
13. Warranty and Support
Your SANSUI F31 speaker comes with a standard manufacturer's warranty. Please refer to the warranty card included with your purchase for specific terms and conditions. For technical support or service inquiries, please contact the retailer or manufacturer's customer service.





