Table of Contents
Reset, Firmware and Maintenance
How to replace the batteries? Where to purchase the required batteries?
The compatible Sennheiser battery is BA 275. It will be available in the EU and further selected countries.
Removing the rechargeable battery
Tools required: Phillips screwdriver PH000
1. Place the TV headphones on a flat, stable surface, such as a table.
2. Remove the ear pad from the left ear cup to protect it from damage.
3. Remove the three Philips head screws from the left ear cup with the screwdriver.
4. Attention! Risk of damage to the speaker cable. Do not pull the acoustic unit off too far and remove it carefully.
Open the left ear cup by pulling the acoustic unit upwards.
5. Disconnect the battery cable plug from the main circuit board.
6. Open the rubber lid that covers the rechargeable battery.
7. Remove the rechargeable battery.
Inserting the new rechargeable battery
▷ Place the rechargeable battery into the holder.
▷ Close the rubber lid.
▷ Connect the battery cable plug to the main circuit board.
▷ Close the ear cup by putting on the acoustic unit.
▷ Attach the acoustic unit by tightening the three Philips head screws.
▷ Reattach the ear pad back onto the ear cup
How to replace the earpads? Where to purchase the required ear pads?
For reasons of hygiene, you should replace your ear pads from time to time.
▷ Grasp the ear pad and loosen the edges all the way around until you can remove the ear pad completely.
▷ Place the new ear pad onto the ear cup so that they are well aligned.
▷ Slide the edges of the ear pad into the groove all around the ear cup.
Which spare parts are available for the RS 255 TV Headphones?
• Additional receiver (= HDR 275 TV Headphones)
• Ear pads
• Replaceable battery
• Headphone stand
How can I update my TV headphones and TV transmitter with the latest firmware?
Firmware updates can be downloaded free of charge from the Internet using the Sennheiser Smart Control Plus app.
For more details, please refer to the RS 255 TV Headphones manual in the chapter “Installing firmware updates”.
How can I reset my TV transmitter?
If the function of the TV transmitter is disturbed and interrupting the power supply (hardware reset) does not improve, reset the TV transmitter to the factory default settings:
▷ Press and hold both SOURCE and SOUND MODE buttons for approx. 30 seconds.
All LEDs of the TV transmitter light up white for one second.
The TV transmitter is successfully reset to the factory settings.
▷ Reconnect your TV transmitter to your headphones and your Bluetooth device.
How can I reset my headphones?
Press and hold the middle button (between the volume buttons) for about 15 seconds.
The status LED will flash red once.
You will hear the power-on tone, confirming the factory reset is complete.
Troubleshooting (If a problem occurs...)
What can I do if the headphones and transmitter won’t connect?
Try the following:
▷ Make sure the TV transmitter is powered on and receiving an audio signal.
You can check this by making sure that the SOURCE LED is lit blue, orange, or white (not flashing).
▷ Check the cable connections between the transmitter and your TV.
▷ Make sure that the TV is actually playing audio. ▷ Make sure that the headphones are switched on.
▷ If the SOURCE LED is flashing, please check the TV settings and make sure that the correct audio output is selected.
If they still won't connect:
▷ Pair the headphones again:
– Press and hold the power button for about 5 seconds until the LED flashes blue and white alternately.
– If the transmitter is streaming and the headphones are nearby, they should automatically reconnect.
How do I get sound only from the headphones and not through the speakers?
The sound from the transmitter is independent of the TV speakers. If you only want to hear sound through the headphones, simply
– mute the TV speakers, or
– turn the TV volume down to 0.
The headphones will continue to receive the audio signal normally, regardless of the volume settings of the TV speakers.
How do I get sound from BOTH the TV and headphones at the same time?
To play audio through both the TV speakers and the headphones:
▷ Use the TV‘s digital audio output (optical/TOSLINK) if available.
On many TVs, the optical output remains active while the TV speakers are turned on, allowing for dual audio output.
▷ Check your TV‘s audio settings for options such as:
– “TV speakers + optical out”
– “Audio output: TV + external device”
– “Multi-output audio”
If your TV does not offer this feature, it may not be possible to play sound through both outputs at the same time.
Why is there reverb or echo when using the headphones with my TV?
This happens because both the TV speakers and the headphones are playing sound at the same time, and the headphones have a slight audio delay. The two signals overlap and create an echo or reverberation effect.
To fix this, we recommend muting the TV speakers or reducing the TV volume to 0 so that the sound only comes from the headphones.
What can I do if the volume is very low?
Try the following:
▷ Increase the volume on the headphones by pressing the volume up button several times.
▷ In the Smart Control Plus app, check the transmitter settings:
Make sure that “Normalize Volume” is set to “Slow” or “Fast” (not off).
▷ Go to your TV's audio settings and set the TV volume to about 60 80% to provide a strong audio signal to the transmitter.
Why is the sound from the headphones slightly behind the video image or speaker sound?
The audio signal sent to the headphones has a slight delay of about 50 ms. In most cases, this delay is so slight that it's not noticeable.
However, if you do notice it, many TVs offer sound delay/lip-sync settings that allow you to adjust the timing so that the sound better matches the picture.
What should I do if the RS 255 TV Headphones suddenly stop working?
Try the following:
▷ Switch the TV transmitter off and on again:
Turn it off, wait a few seconds, and then turn it back on.
▷ Reset both devices to factory settings:
Perform a factory reset on the TV transmitter and the headphones.
Further information on resetting to factory settings can be found here.
This usually resolves unexpected problems and restores normal operation.
What should I do if the sound on my RS 275/255 TV Headphones keeps cutting out?
Try the following:
▷ Switch the headphones off and on again to reset the connection.
▷ Move closer to the TV transmitter to improve signal strength.
▷ Reduce interference by keeping other wireless devices (Wi-Fi routers, cordless phones, smartphones, or other Bluetooth devices) away from the transmitter and headphones.
What can I do if there is interference from radio signals (or Wi-Fi)?
Remove or turn off other wireless devices near the headphones and TV transmitter, such as:
• Wi-Fi routers
• Cordless phones
• Smartphones
• Other Bluetooth devices
Reducing the number of radio signals in the environment can improve the connection and reduce interference.
Why does my TV switch back to HDMI-ARC when I try to select the optical output?
Some TVs prioritise HDMI-ARC as the default audio output over other connections. In addition, certain soundbars connected via HDMI-ARC may automatically override the TV's audio output settings.
A possible workaround is to connect the TV transmitter via HDMI ARC and your other device via the optical output.
In most cases, the BTA1 TV Transmitter will only follow the HDMI output when it is actively in use.
Why does the transmitter's SOURCE LED light up blue when I connect the analog cable?
The transmitter automatically detects when a cable is connected to the analog input and switches to that input, which is indicated by a solid blue SOURCE LED.
If the cable is not connected at the other end, the transmitter may detect ambient noise as an audio signal, which can cause streaming interference or unintended sound.
Why do I hear noise or static when streaming audio via USB C (via a docking station or USB dongle)?
Some USB controllers can cause audio quality issues, such as noise or static. To resolve this, connect the transmitter to a different USB port or directly to the device, bypassing hubs or docking stations if possible.
Why does the volume seem to fluctuate on its own when watching TV?
This may be because some TVs do not respond to the “Normalize Volume” function as intended.
The “Normalize Volume” function is designed to improve listening comfort by amplifying quieter sounds and reducing sections that might otherwise be too loud. On some TVs or set-top boxes, these adjustments can be more pronounced and occur quickly, which can lead to noticeable volume fluctuations.
To prevent this effect, disable the function “Normalize Volume” in the Smart Control Plus app.
Why does the SOURCE LED light up red when the optical cable is connected?
A red SOURCE LED indicates an unknown or unsupported audio codec on the optical input. This can happen if the optical output is not selected as the TV’s audio output.
▷ If you are using the TV transmitter and the optical output is selected, change your TV‘s audio codec to a supported format (e.g., Dolby Digital).
▷ If another device, such as a soundbar, is currently using a different TV output, you can ignore the red LED. It simply indicates that there is no valid audio signal on the optical connection.