RS 275/255 Operation

When fully charged, you can enjoy up to 50 hours of playback time. Actual battery runtime may vary depending on volume, activated functions, and the connected device (e.g., iPhone, Android phone, PC, or TV transmitter).

The headphones offer up to 50 hours of playback, but the actual battery runtime depends on the volume, activated functions, and the connected device (e.g., iPhone, Android phone, PC, or TV transmitter). If you've owned your headphones for several years, the battery may hold less charge over time. Don’t worry: the batteries of the HDR 275 TV Headphones are replaceable, so you can easily refresh your headphones–click here for more info.

When using a charger at full capacity, it takes approximately 2 hours to fully charge the headphones.

TV transmitter: 

• If one or more LEDs are lit, the transmitter is switched on. 

• If no LEDs are lit, make sure that the transmitter is connected to the power supply and that your TV is switched on. Press any button on the transmitter to wake it up. TV headphones: 

• Briefly press the power button. – If the LED flashes white, the headphones are now switched on. –If nothing happens or the LED lights up purple, the headphones are already switched on. 

• If you still cannot hear any sound, make sure that the headphones are charged. For information on connection problems, please refer to the troubleshooting guide here.

Yes. If your USB power adapter doesn't provide enough power, your headphones will simply charge more slowly. 

The good news: Almost all modern chargers for smartphones, tablets, and laptops provide more than enough power for full-speed charging. 

Minimum requirements:

– Current: at least 400 mA (0.4 A)

–Voltage: between 5.0 V and 5.5 V 

Examples of compatible chargers:

–5.1V, 1500mA (1.5A)

–5.0V, 2A–5.0V, 1.2A

–5.0V, 1A–5.2–5.3V, 2A

–5V, 4.5A 

All of these meet the requirements, as they can supply more than 0.4 A and remain within the range of 5.0 to 5.5 V.

Yes, but with a limitation: 

The USB C output provides less than 500 mA of current, so not all devices can be charged properly or at all. 

It works best for low-power devices, such as headphones or small accessories, but smartphones or tablets may charge very slowly or not at all.

To check the battery level, double-press the power button. The headphones will then indicate the current charge level.

You can safely charge your headphones overnight, as charging process stops automatically once the battery is fully charged. However, avoid storing the headphones for long periods of time with the battery completely discharged, as this can affect the battery's service life.

The battery model is called BA 275 and can be purchased on our accessories website,

No, the headphone stand is for storage only. Charging is done via the USB cable, which provides a convenient and reliable way to charge your headphones.

Several factors can affect charging: 

• Changed USB port: If you have changed the USB port on the TV transmitter, it may be supplying less power. Try using the original port or power supply. 

• Heavily discharged battery: If the headphones’ battery was completely discharged, charging may take longer than usual. 

• Aging battery: Older batteries may charge more slowly and have a shorter runtime. Consider replacing the battery if necessary. 

• Charging cable: Using a different cable may affect charging. Use the USB cable provided.

Bluetooth Auracast™ allows you to broadcast audio from your TV or other devices to multiple headphones or earbuds at the same time, making it perfect for shared listening. 

In contrast, Bluetooth Classic only connects to one device at a time, which is ideal for personal use such as listening to music or making calls.

 For more details, you can read an article about Auracast™ here .

Theoretically, an unlimited number of Auracast™ headphones can be connected to a single TV transmitter/Auracast™ stream. In practice, a transmitter can typically support between 200 and 500 headphones while maintaining good performance.

You can connect any headphones or earbuds that support Bluetooth Auracast™. Standard Bluetooth Classic headphones will not work with the Auracast™ broadcast.

The TV transmitter automatically starts broadcasting as soon as it is powered on. You can verify that audio is being transmitted by checking the SOURCE LED on the transmitter—if it is lit continuously (not flashing), the audio stream is active.

You can rename your Auracast™ stream using the Smart Control Plus app. Simply connect your transmitter with the app and update the name in the Broadcast Settings menu. 

The name you choose will appear in your Auracast™ assistant, making it easier to identify your stream. Especially when multiple broadcasts are available nearby.

You can enable stream encryption through the Smart Control Plus app. Simply connect your transmitter with the app, go to the Broadcast Settings menu, and activate encryption, then set a password. 

The security of your stream depends on the strength of the password you choose. The Smart Control Plus app also includes a feature to generate a strong, random password for increased protection. 

Although encryption improves data protection, the Auracast™ password is not unbreakable, and absolute security against offline brute force attacks to recover the key cannot be guaranteed.

Yes, provided your hearing aids support Auracast™. Please note that the TV transmitter's Auracast™ stream is set to high quality with a sampling rate of 48 kHz by default. Some Auracast™ devices, including certain hearing aids, may not support this setting. 

Using the Smart Control Plus app, you can select a lower sampling rate to ensure full compatibility with any Auracast™-enabled devices.

– With the TV transmitter (Auracast™): up to 50 meters

– With Bluetooth Classic: up to 25 meters 

The actual range may vary depending on the environment—for example, walls, furniture, or a large number of Wi-Fi devices can reduce the effective distance.

No, a single transmitter can only stream one audio source at a time. 

However, you can use multiple TV transmitters to stream different sources simultaneously.

The system latency is approximately 50 ms. 

Latency is the slight delay between an audio signal entering the system and the moment you actually hear the sound. For most users, a latency of 50 ms is so low that it is imperceptible. 

During normal TV operation, audio and video should remain synchronized.

Yes! The headphones can be connected to any mobile phone that supports Bluetooth Classic, allowing you to listen to music, watch videos, or make phone calls.

Yes! The headphones support phone calls when connected to a mobile device via Bluetooth Classic, allowing you to make hands-free calls while enjoying your audio.

Yes, please note that the BTA1 is only compatible with Bluetooth speakers that support Auracast™ technology. 

You may need an interface or app for the speaker to search for Auracast™ streams and select the BTA1. Please refer to your speaker's user manual for more information.

Yes, the headphones support the following codecs: 

• SBC 

• AAC 

• aptX™ 

• aptX™ Adaptive 

• LC3 

Important: The TV transmitter only uses Bluetooth Low Energy (LE) audio with the LC3 codec. 

Therefore, when you connect the headphones to the transmitter, only LC3 will be used.

You can operate the headphones in various ways: 

• On the headphones: Use the physical buttons for functions such as play, pause, volume up, and volume down. 

• Smart Control Plus app: Offers additional settings and control options. 

• Media control via Bluetooth device: Some functions (play, pause, volume) can also be controlled directly via your device, e.g., smartphone.

You can save your hearing enhancement settings (i.e., hearing profiles, speech clarity, noise suppression) in the app. 

By briefly pressing the power button on your headphones, you can access the hearing enhancement feature and the Graphic Equalizer, see details below. 

If Hearing Enhancement and Graphic EQ are activated: Hearing Enhancement Graphic EQ 

If only Hearing Enhancement is activated: Hearing Enhancement ON Hearing Enhancement OFF

The transmitter has two buttons: 

• SOURCE: Switch between different audio inputs. 

• SOUND MODE: Switch between three sound modes or turn the sound off completely. 

For additional settings and more convenient control, you can also use the Smart Control Plus app.

The Sennheiser Smart Control Plus app gives you full control over your headphones and transmitter. 

Here are three key benefits: 

• Firmware updates – keep your headphones and transmitter up to date with the latest features and improvements. 

• Personalized hearing enhancements – adjust hearing profiles, noise suppression, and the balance between the left and right channels (only available in the app). 

• Secure Auracast™ streaming – enable encryption for your audio streams. 

The app ensures you get the best performance, a personalized experience, and the latest features for your devices.

▷ Activate Bluetooth on your smartphone with the Smart Control Plus app installed. 

▷ On the TV transmitter, simultaneously press and hold the SOURCE and SOUND MODE buttons for 5 seconds. The SOURCE LED will start flashing green, indicating the transmitter is ready to connect. 

▷ Open the Smart Control Plus app on your smartphone, tap the “+” icon on the start screen to add a new device, and select the TV transmitter from the list. 

▷ When your smartphone prompts you to allow pairing with a new device, approve the connection. 

▷ Once pairing is successful, the TV transmitter will appear in the list of connected devices. Select “BTA1 TV Transmitter” to establish the connection.

The TV transmitter only connects to your smartphone to configure settings via the Smart Control Plus app. A standard Bluetooth connection, such as the one used for headphones, is not required and is therefore not supported for this purpose.

The TV transmitter connects to Smart Control Plus via Bluetooth Low Energy (BLE). 

On most smartphones, BLE connections can be restricted or interrupted when an app is closed or running in the background. 

This is normal behavior designed to conserve battery power and system resources. 

Therefore, the transmitter may appear disconnected when the app is not active. 

As soon as you re-open the app, it will automatically attempt to re-establish the connection. To maintain an active connection, leave the Smart Control Plus app open and running in the foreground.

Step 1: Pair with your smartphone via Bluetooth 

▷ Make sure that there are no TV transmitters nearby or powered on. The headphones may automatically connect to them during the pairing process. 

▷ Press and hold the power button on the headphones for approximately 5 seconds. The headphones are in pairing mode when the LED flashes blue and white alternately. 

▷ On your smartphone: 

–Go to the Bluetooth settings and activate Bluetooth. 

– Search for a new device named “HDR 275”.

– Select it and accept/connect if prompted. 

Step 2: Connect via the Smart Control Plus app 

▷ Open the Smart Control Plus app. 

▷ Your headphones (HDR 275) should be detected automatically. If this is not the case, tap the “*” icon in the upper left corner to search for connected devices. 

▷ Select HDR 275 from the list to establish the connection.

Yes, you can use the TV headphones with your PC or laptop. 

There are several ways to connect them: 

• TV headphones connected directly to your laptop/PC via USB 

• TV headphones connected to your laptop/PC via Bluetooth Classic 

• TV transmitter connected to your laptop/PC via USB, streaming Auracast™ to the TV headphones 

Please note that the connection via the TV transmitter does not support an audio return channel. 

Therefore, telephony function is not available in this configuration.