sennheiser cx 400bt review

Sennheiser CX 400BT True Wireless Review

If you’re one of those people who enjoy listening to music while on the go, don’t worry, you’re not alone. Music soothes and keeps us going during hectic days, so you’d want a pair of earbuds that produce superior sounds. Take a look at our Sennheiser CX 400BT True Wireless review to get details on excellent quality earbuds.

The CX 400BT True Wireless from Sennheiser is powered by the company’s leading audio technology. It’ll give you full control over outstanding sounds and quality.

With longer-lasting battery life, a design made for everyday comfort, and customisable controls, these are the real deal. The CX 400BT True Wireless is an uncompromised choice for everyone passionate about outstanding sounds and performance.

If you’re curious about these amazing earbuds from Sennheiser, continue reading through our review to learn more.

Sennheiser CX 400BT True Wireless Packaging

Taking a look at our Sennheiser CX 400BT True Wireless review, we’ll first focus on the earbuds’ packaging and contents.

The CX 400BT True Wireless comes in a blue and white-themed cardboard box. In front, you’ll find an image of the earbuds. Sennheiser and its logo are written on each of the top corners of the box.

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Above the image, you’ll find the name of the buds; below it are some features of the product. The sides and rear of the package have additional information about the earbuds that you may find essential.

Aside from the CX 400BT True Wireless earbuds, you’ll also find a set of ear adapters. These are made of silicone and they come in different sizes ranging from extra small to large.

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There’s a charging case present, a USB-C cable, as well as a quick user & safety guide for your reference.

Sennheiser CX 400BT True Wireless Review – Design and Functionality

Let’s focus on the design and functions of the earbuds in our Sennheiser CX 400BT True Wireless review.

These earbuds utilise the same 7mm full-range dynamic driver of the company’s Momentum True Wireless 2. The difference is that the CX 400BT True Wireless doesn’t have the latter’s active noise-cancelling technology.

We love that Sennheiser included differently-sized ear tips in the box, plus their twist to fit arrangement. Once you get the right fit, you’ll get a lot of passive noise-cancelling features delivered by these earbuds.

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For the earpieces, these are designed to be compact, and only utilises ear tips to keep everything in place. You won’t find any stems like those on the Apple AirPods Pro. There aren’t additional ear fins as well, which are present on a lot of sports-focused earbuds today.

Still, the fit’s comfortable and secure, but not secure enough to work as in-ear pieces to use for the gym. Also note that it doesn’t come with any IP rating for water resistance, so avoid getting these wet.

The CX 400BT True Wireless comes with a flip-top case which is a bit tiny. It isn’t as small as the case of the AirPods Pro, but we’d still categorise it as small.

Its back panel is where you’ll find the USB Type-C port for its included cable. Here, you’ll also find a button displaying the case’s battery life on the LED that’s positioned closely.

Its sizable earbuds note that there’s a lot of room for capacitive touch surfaces. This layout only proves that the buds are simple and highly responsive to operate.

Between the right and left buds, you’ll find the usual controls housed in the area. These include play/pause, answer/end/reject a call, volume up/down, and the summon voice assistant controls.

The touch-sensitive panels on the left and right earpieces segregate the controls smartly and intuitively. On the left panel, it handles music playback via a single tap. The right panel answers calls or brings out the voice assistant.

Double-tapping on the left section backtracks the audio; the right section skips the audio forward or ends your call. Giving a long press and holding on either of these will let you adjust the volume.

Out of the box, you’ll have the triple tap left unassigned. If you prefer leaving things as is, you can utilise the action for the voice assistant instead.

Sennheiser also gives you the ability to restore the earbuds’ default controls just by single tapping. This’ll come in handy when you dislike the controls that you’ve set. What’s more, you can entirely disable the touch controls if needed.

The CX 400BT True Wireless’ controls are highly responsive and rarely need additional taps. Honestly, we think these are some of the easiest on-ear controls that we’ve ever utilised. Not only that, but Sennheiser was able to cram almost every necessary control there.

It may appear as the norm, but a lot of models still implement incomplete and jumbled control panels. With that, kudos to the company for getting it right.

When it comes to the voice assistants, these extend as far as Google Assistant and Siri. This is all thanks to the sharp microphones that are present on each earbud. Here, your assistant will easily understand your commands, executing these adequately.

Our Sennheiser CX 400BT True Wireless review will now tackle the different key features of the CX 400BT True Wireless.

Key Features of the Sennheiser CX 400BT True Wireless

This is where we discuss the key features of the earbuds in our Sennheiser CX 400BT True Wireless review.

Better Sound and Control

The Sennheiser CX 400BT True Wireless features bespoke drivers that deliver high-fidelity audio. With that, sounds will have natural mids, deeper bass, and clear, detailed treble.

Additionally, you can personalise your audio experience with the integrated equaliser via the Smart Control App. The CX 400BT True Wireless lets you enjoy superior sound quality tailored for you.

Premium Sound on Any device

Whether you use Android or iOS, you can use the CX 400BT True Wireless and enjoy premium audio. With its wide range of audio codec support, you’ll enjoy high-quality sound, no matter what mobile device you use.

Listen Anytime

You won’t have to miss a bit with these earphones’ 20 hours of battery life. A single charge gives you 7 hours of playtime, plus 13 extra hours from the charging case. It’s designed to give you high-quality sound for long periods.

Minimalist, Stylish, and Comfortable

The CX 400BT True Wireless has an excellently ergonomic design, made for all-day wearing. With that, you can enjoy listening to your favourite songs all day without feeling discomfort.

This time, let’s check out the different specifications of the earbuds in our Sennheiser CX 400BT True Wireless review.


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The earbuds and charging case measure 59mm x 33.8xx x 42.3mm and weigh 49g in total. The earbuds weigh 6g each, while the charging case is 37g on its own. As for the package, it measures 170mm x 115mm x 47mm (LxBxH).

CX 400BT True Wireless’s THD or total harmonic distortion is <0,08% (1kHz / 94dB). Its standard USB is the USB Type C, and it makes use of the Bluetooth 5.1 compliant version.

For the earbuds’ frequency response, it ranges from 5 – 21,000Hz while its microphone is 100Hz to 10kHz. Ear coupling is an in-ear piece with closed acoustics.

Supported profiles for the earbuds include AVRCP, A2DP, HFP, and HSP, while codecs are AAC, SBC, and aptX.

When we speak of the earbuds’ battery, it makes use of integrated Lithium-ion rechargeable batteries. These last up to 7 hours for music playtime but goes for up to 20 hours with the charging case.

If you need to charge, you’ll need 1.5 hours for a full charge. Ten minutes of charge will give you an hour of music playtime. USB charging is done via USB-C socket on the charging case.

For convenience, Sennheiser included a two-year warranty for their CX 400BT True Wireless earbuds.

Hands-on with the Sennheiser CX 400BT True Wireless

This is the part of our Sennheiser CX 400BT True Wireless review where we look into the earbuds’ performance. But first, let’s check out how the Smart Control App worked.

Sennheiser Smart Control App

This application from Sennheiser allows you to customise the on-board controls for the earbuds. Unlike its competition, you can reassign almost every action on both earbuds via the application.

On most available earbuds, you can select between three functions for a single specific gesture. With the CX 400BT True Wireless, you can remake the touch controls almost entirely if you dislike the default settings.

The Sennheiser Smart Control app includes a user-adjustable EQ while offering a straightforward graphic EQ. It features three bands for lows, mids, and highs. If not, you can opt for animated graphics that utilises the same sonic parameters.

These appear like the ocean’s surface reacting to your swipes.

Smart Control is a free application that’s compatible with most Android and iOS systems. It’s available in 8 different languages, including English, Korean, Japanese, Spanish, French, Russian, German, and Mandarin.

Audio Quality

Sennheiser claims that the earbuds feature the same acoustic system as their Momentum True Wireless 2. This includes its 7mm dynamic driver that the company utilises on their more expensive models.

As for the sound quality of these earbuds, they’re good and clear. These have amazing quality and details for most music genres. Additionally, it has a warm and deep soundstage that we enjoyed.

There audio simply sounds fantastic and are an ideal option for anyone concerned about audio performance.

The CX 400BT True Wireless offers a powerful and excellent low-frequency response. When we used these at top volume, the lows didn’t distort. Using these at moderate volume provided full sounds for the bass depth without overwhelming the mix.

Drums sound great with the help of bass depth, giving you a sound that’s powerful, full, and not over boosted. You’ll get a slightly heavier yet natural sound compared to what you’d hear from flat-response earphones.

For the vocals, you’ll receive a lot of low-mid richness. As for the highs and high-mids, these are crisp, providing adequate balance to the audio.

Generally, the CX 400BT has outstanding balance throughout its frequency range with some subtle enhancements on the lows and highs. Everything sounded natural, and the audio it produced wasn’t anything over-the-top.


As promised, the CX 400BT True Wireless does have 7 hours of battery life. It has an additional 13 hours when inside the charging case. These earbuds will suit pretty much anyone that is serious about their audio. They will last the better part of a full working day and if the battery does start to run down just pop them into the case and quickly charge them again and your good to go.


Lastly, the microphone was able to offer solid performance and efficiency. Utilising the Voice Memos application on the iPhone 8 allowed us to fully understand every recorded word clearly.

As for the mic’s signal, it was strong. So, callers won’t have any issues hearing or understanding the other person on the line. Just make sure that your mobile signal is strong as well to make for clear calls.

Overall, the Sennheiser CX 400BT True Wireless performed excellently, and the sounds it produced were great. Everything was clear, there were barely any distortions, and the mic performed just as excellently.

Sennheiser CX 400BT True Wireless Review Summary

The CX 400BT is Sennheiser’s more affordable option among their series of true wireless earbuds. Although it has no noise cancellation features, it delivers excellent audio performance.

Also, these earphones are easy to use, plus the audio and controls are highly customisable via the app.

In fact, this pair is among the best true wireless earbuds that we’ve used, and we were satisfied with them.

To sum up our Sennheiser CX 400BT True Wireless review, we highly recommend this product. If you want to get your hands on these earphones, it’s available for purchase from the company’s official website.