Modern smartphones like the Xiaomi Redmi 9 are equipped with advanced wireless modules that make it easy to get rid of unnecessary wires. The process of pairing audio devices with a phone has become much easier, but there are nuances in the MIUI shell that can confuse the inexperienced user. Proper tuning of a Bluetooth connection guarantees not only stable audio transmission, but also high quality audio when listening to music or during games.
In this article, we will discuss in detail all the stages of connection, from activating the module to fine-tuning the codecs. You will learn how to make old models of headphones work and how to optimize the operation of new devices with support for AptX or LDAC. Following the recommendations will help avoid common synchronization errors.
It's worth noting that the MIUI-based Android operating system is updated periodically, changing the location of some menu items, but the basic principle of pairing remains the same for all firmware versions, the key is to enter the device properly in search mode, which often becomes a stumbling block.
Preparation of headphones and smartphone for pairing
Before you try to find a device on the list of available, you need to make sure that both gadgets are ready for communication. For the Xiaomi Redmi 9, this means checking the battery and Bluetooth module. If the phone is in power saving mode, the system can limit the background operation of the wireless scanner, which will make it difficult to find.
Special attention should be paid to the headphones themselves. Many users forget that just turning them on is not enough - you need to activate the visibility mode. TWS-models that often go into this mode automatically when removed from the case, full-size headsets require a special button to be pressed.
☑️ Connection readiness
Make sure there are no other active Bluetooth devices around that can intercept the signal or cause interference. Sometimes Redmi 9 tries to automatically connect to previously known gadgets, ignoring the new device, in which case a temporary Bluetooth shutdown on neighboring smartphones or tablets will help.
Bluetooth activation and device search in MIUI
The MIUI shell interface offers two main ways to turn on the wireless module: the fastest is through the notification curtain. Swipe down from top to bottom to open the control panel, and find the icon in the form of the letter "B." If it is gray, click on it to activate the search.
A deeper setup is available through the system menu. Go to Settings → Bluetooth or search by settings by entering the word "Bluetooth." Here you will see a switch at the top of the screen. Once activated, the phone will start scanning the airwaves.
⚠️ Warning: Don't leave the search screen open too long unnecessarily.Constant scanning drains Xiaomi Redmi 9 battery faster than usual as radio module runs at increased power.
The device name usually corresponds to a headphone model or brand, such as AirDots, Sony WH or simply Bluetooth Audio. If the device does not appear within 10-15 seconds, press the Update button or re-enter the pairing mode on the headset.
The pairing process and confirmation of connection
When a device is found, click on its name in the list. A request to confirm pairing with the code or simply a notification of an attempt to connect may appear on the smartphone screen. For most modern headphones, no code is required, and the connection is established automatically after pressing.
In some cases, especially when connecting older models or car systems, Xiaomi Redmi 9 will request input. PIN-The standard combinations are usually 0000 or 1234, and this should be included in the instructions for the audio device.
Successful connectivity is accompanied by a characteristic beep in the headphones and a change in status in the phone menu. the status "Connected" will appear under the device name, and in the status bar will appear a small icon of headphones or batteries, if the headset supports the transfer of charge level.
What to do if you need a password?
Customization of sound quality and codecs
After a successful connection, it's important to make sure that the sound is transmitted in the best possible quality.The Xiaomi Redmi 9 supports various audio codecs such as SBC, AAC and, depending on the version of the processor, AptX. The choice of codec affects bitrate and audio delay.
To access the advanced settings, you need to activate the developer menu. Go to Settings → About the phone and quickly press 7 times on the item "Version" MIUI". After that, the "Additional" menu will appear "For developers".
| Codec | Sound quality | Delay (Latency) | Compatibility |
|---|---|---|---|
| SBC | Basic | Tall. | All devices. |
| AAC | Good. | Medium | Apple, Android |
| AptX | High. | Low. | Qualcomm, Android |
| LDAC | Hi-Res | Variable | Sony, flagships |
In the developer menu, find the Bluetooth Audio Codec (or Bluetooth Audio Codec), where you can force the right format to choose if the headphones support it, but automatic selection by the system is usually the most stable option, since the phone itself matches the capabilities with the headset.
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For games, turn on Low Lag Mode in Bluetooth settings if your headphone model supports Game Mode technology.
Managing Connected Devices and Profiles
Xiaomi Redmi 9 allows you to flexibly manage connected gadgets. In the Bluetooth menu, if you click on the arrow next to the device name, you can see a list of profiles: Audio, Media, Phone. You can turn off the audio transmission by leaving only the microphone, or vice versa.
If you have multiple devices connected to your phone, like smartwatches and headphones, the priority of the sound can be randomly switched. Bluetooth settings have a "Replay Media on" feature that allows you to rigidly specify the source of the output of the sound.
To disable or delete the device, just click on the gear or arrow icon to the right of the name and select "Disable" or "Forget the device." This action will break the communication and delete the encryption keys, which is useful when selling headphones or fixing connection errors.
⚠️ Attention: Forget device removes all equalizer settings and specific profiles for that particular pair.
Solving Common Connection Problems
Despite the simplicity of the procedure, users often face problems: the phone does not see the headphones, the sound is interrupted or absent. The first and most common reason is a crowded Bluetooth cache. You can clean it through the application menu: find the system process "Bluetooth" in the list, go to storage and click "Clear cache".
The second common problem is Bluetooth version conflict: If you’re trying to connect a very old device (version 2.0 or 3.0) to a modern Redmi 9 (version 5.0+), protocol failures can occur, in which case the phone’s network settings reset helps.
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If the sound is wheezing or interrupted, try turning off the "Absolute Volume Level" feature in the developer menu, which often solves the problem of de-synchronizing the volume.
It's also worth checking if Monoaudio is included in the special features section. Sometimes activating this feature for the hearing-impaired distorts the stereo panorama, creating the illusion of a bad connection. Turn it off in the Settings menu → Advanced Settings → Special features.