Home Audiophile Earbuds Manuals The Sennheiser CX 400BT are a pair of earbuds with a great quality, not only because of their comfort and small size, but they also have a 7.5-hour battery life and a host of smart features. Today you will learn how to use them with this Sennheiser CX 400BT Manual. What's Inside Sennheiser CX 400BT Manual | Pairing & Charging InstructionsSennheiser CX 400BT Manual | How to Pair / Connect?Sennheiser CX 400BT Manual | How to Place Them?Sennheiser CX 400BT Manual | How to Charge?Waking up the earbuds and the charging case / charging the rechargeable batteriesSennheiser CX 400BT Manual | LED Light StatusHow to Control? / How to Operate? – InstructionsSennheiser CX 400BT Manual | How to select the best ear adapters?Sennheiser CX 400BT Manual | How to Reset?A Guide To Sennheiser CX 400BT APPSome Common Earbuds Problems & TroubleshootingFAQs Sennheiser CX 400BT Manual | Pairing & Charging Instructions Sennheiser CX 400BT Manual | How to Pair / Connect? Step 1: Take the earbuds out of the charging case and press the touch panel on both earbuds for 3 seconds to pair them. Step 2: Turn on the Bluetooth on the desired device. Step 3: Go to the Bluetooth settings. Step 4: Select the “CX 400BT TW”. If necessary, enter the default pin code “0000”. Step 5: If the pairing was successful, you will hear the voice prompt “Pairing successful” and the LED lights on the earbuds will flash blue 3 times. For Laptops (Windows) Step 1: Turn on Window’s Bluetooth. Step 2: Go to the settings. Step 3: Go to “Bluetooth and other devices”. Step 4: Click on “Add device”. Step 5: Click on Bluetooth. Step 6: Take the earbuds out of the charging case so they turn on and pair to each other automatically. Step 7: The earbuds by the name “CX 400BT TW” will appear on the settings. Step 8: Select and, after this, the earbuds will automatically connect to the desired device and will be ready to use. Sennheiser CX 400BT Manual | How to Place Them? Step 1: You have to assign the right earbud into the right ear, and the left earbud into the left ear, making this using the “L” and “R” letters on the earbuds. Step 2: Insert the earbuds at a slight angle into the ears, and twist them slightly into the ear canal so that they sit comfortably into the ear canal. Sennheiser CX 400BT Manual | How to Charge? Earbuds Step 1: Place the earbuds into their place on the charging case. Step 2: A LED light on the earbuds will turn yellow and they will automatically start charging. Step 3: When fully charged, the red light will turn green. Charging Case To charge the charging case, all you have to do is to connect the case to a computer or USB Type-C output device. Waking up the earbuds and the charging case / charging the rechargeable batteries Upon being delivered, the rechargeable batteries on the earbuds and the charging case are in “sleep mode”, and have to be “woken up” by connecting them to a power source once. To do this, you have to do de following steps: Step 1: Insert the earbuds into the charging case. Step 2: Connect a USB Type-C into the charging case and to a power source. After this, the earbuds and case are woken up and the rechargeable batteries will start charging. The earbuds are ready to use. Alternatively, you can do the following: Press and hold the LED button on the charging case on the charging case for 3 seconds. Sennheiser CX 400BT Manual | LED Light Status Earbuds Red and blue lights flashing for 1 minute approx.: Earbuds in Bluetooth mode.Blue lights flash 3 times: Bluetooth earbud pairing successful.Red lights flash 3 times: Bluetooth earbud pairing failed.Blue consistent light: The earbuds are connected to a device via Bluetooth.Red consistent light: The earbuds are not connected to a device via Bluetooth / the connection has been lost.Red lights flash quickly: Rechargeable battery is almost empty.Red lights flash slowly: System error. The Smart Control app may display details.Red and green lights flashing for 1 minute approx.: The earbuds are in pairing mode.Green light: Fully charged.Yellow light: Charging.Red light flashing (when charging): A charging error/battery error has been detected in at least one earbud. Case Green light: Fully charged.Yellow light: Charging.Red light flashing: A charging error/battery error has been detected in at least one earbud/charging case. How to Control? / How to Operate? – Instructions Increase volume: Touch and hold the touch panel on the right earbud until the volume is increased.Decrease volume: Touch and hold the touch panel on the left earbud until the volume is reduced.Play or pause music: Touch the touch panel on the left earbud once.Play the previous song: Touch the touch panel on the left earbud twice.Play the next song: Touch the touch panel on the right earbud twice.Accept an incoming call: Touch the touch panel on any of the earbuds once.End a call: Touch the touch panel on any of the earbuds once.Reject an incoming call: Touch the touch panel on any of the earbuds twice.Accept an incoming call and end the active one: Touch the touch panel on any of the earbuds once.Reject an incoming call and continue the active one: Touch the touch panel on any of the earbuds twice.Activate the voice assistant: Touch the touch panel on the right earbud once. Sennheiser CX 400BT Manual | How to select the best ear adapters? The perceived sound quality, including bass, performance, and the best possible noise cancellation of any earbuds depends to a large extent on the correct fit of the buds into the ear. To place the ear adapters correctly on the ear, you have to do the following: Step 1: Pull the ear adapter away from the in-ear sound tunnel. Step 2: Mount the new ear adapter to the in-ear sound tunnel. Ensure that it locks into place. Step 3: Test which ear adapter size gives you the best sound quality and the best wearing comfort. You can choose between 4 different ear adapters in size XS, S, M and L. Sennheiser CX 400BT Manual | How to Reset? Step 1: Make sure that the contacts on the earbuds and in the charging case are clean and make contact. Step 2: Use a USB cable to connect the charging case to a power source. Step 3: Place both earbuds in the charging case. Step 4: Touch and hold the touch panel on both earbuds for 5 seconds. Step 6: After this, the reset procedure is complete. A Guide To Sennheiser CX 400BT APP The Sennheiser CX 400BT can be used with an application, called Sennheiser Smart Control. This application is available for iOS and Android devices. Through it, the user will be able to see information about the earbuds, as well as all the internal characteristics that it has, in addition to being able to change and update them. First page: This is the home page, and it shows the battery percentage of the earbuds and the menu.Second page: This is the equalizer, where you can change and modify the bass, tremble and others in the earbuds.Third page: Here are the devices to which the Sennheiser CX 400BT are connected. As you like, they will be able to connect or disconnect from the earbuds with a single click.Fourth page: Earbuds controls. Here you will be able to see the available controls of the earbuds and, also, they will be able to be modified depending on the user’s tastes.Fifth page: You will be able to see all the specifications of the earbuds, as well as the possibility of changing certain factory features of these.Sixth page: Here, you will be able to see the firmware version, and you will be able to update it if necessary.Seventh page: Finally, there are the settings of the app, where you can choose a language, see its version and reset it if necessary. Some Common Earbuds Problems & Troubleshooting Problems Left / Right / One side of the earbuds have stopped working If this happens, it may be because it is low on battery or it did not connect correctly with the device. To fix this, you can do the following: 1. Try changing the earbud, placing it in the charging case. 2. Try factory reset and connecting the earbuds with the device again. If that doesn’t work, the earbud is probably faulty, and I can go for a refund or replacement of it. Left / Right / One side of the earbuds has low volume If this happens, it may be because the earbuds are dirty or the volume is set low. To fix this, you can do the following: 1. Try cleaning the earbud using a cotton swab or carefully clean the mesh with a pin. 2. Use the earbuds to increase the volume. Microphone not working If this happens, it can be because the microphone is muted or it has a defect. To fix this, you can do the following: 1. Try checking the device microphone volume or earbud’s app microphone settings to see if it isn’t muted or low. If that doesn’t help, there might be a defect in the earbud, try replacing it or get a refund. Sennheiser CX 400BT earbuds not connecting to Windows/laptop/PC or asking for a code? If the earbuds are earbuds not connecting, it can be because the Bluetooth on the computer has a pairing problem. To fix this, you can do the following: 1. Try disabling Bluetooth from nearby devices >>> then activate pairing mode of the earbuds, pair and connect earbuds from Settings >>> Bluetooth & other devices >>> Add a new device >>>> elect Bluetooth, 2. Try uninstalling and reinstalling the Bluetooth driver, or update the Bluetooth driver. All can be done in Manage >>> Device Manager, reset earbuds (if available), and then repeat the step. 3. Try resetting the earbuds as said in the pairing section above. Now, if the PC is asking for a code, try using the common pairing numbers, such as 0000, or 1234. Credits: TECHTOYREVIEWS FAQs Are the Sennheiser CX 400BT waterproof? While current earbuds typically have some water resistance, the Sennheiser CX 400BT are not sweat or waterproof. What is the latency of Sennheiser CX 400BT? When talking about its latency, the Sennheiser CX 400BT earbuds shows around 160 to 180 ms. Does Sennheiser CX 400BT have a microphone? Yes, the Sennheiser CX 400BT have an integrated microphone. How to know when Sennheiser CX 400BT are fully charged? When the Sennheiser CX 400BT are fully charged, their LED light turns on yellow. We hope you now know how to operate the earphone from the above Sennheiser CX 400BT Manual. Want to know anything about the earphones? Do not hesitate to ask in the comments section. Moreover, Sennheiser provides in-depth instructions and troubleshooting problems on this page.