Sennheiser CX 400BT True Wireless – Hardware Review
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Developer: Sennheiser
Publisher: Sennheiser
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Sennheiser CX 400BT True Wireless – Hardware Review

Good: Affordable, Quality sound, Battery life
Bad: Need to find that proper fit
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(2 votes)
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Rating: 8.5/10 (2 votes cast)

Even though we often write about big and bulky headsets, we sometimes also prefer to keep it a bit smaller and more subtle, especially for outdoor usage. Sennheiser has many different solutions for this situation, and we were lucky enough to receive a review sample for the CX 400BT True Wireless earbuds. We have already discussed wireless earbuds in the past, and we were impressed by the technology at that time; but also hesitant as there was a lot of quality loss. Now, however, it seems that we can very much enjoy premium quality audio in a bite-sized package.


Just like other Sennheiser products, the device does not come with too many bells and whistles. You’ll have sleek black earbuds, albeit with a bigger protruding portion compared to wired earbuds. Nonetheless, the added portion that encapsulates all the hardware for each earpiece isn’t too big and will not stick out too much. You’ll have the company’s logo featured on both earbuds, and that’s basically it. There is also a small LED on the inside of each device, to show if it’s working or not.

There is a small charging case included with the earbuds, serving as the charger and a small case to keep your hardware safe. Like the earpieces, the case is very down to earth and just dons a completely black design, with a glossy Sennheiser logo on the lid. Other than that, there’s a small button on its back, to show the battery level of the earbuds by a LED that lights up.


Even with the extra bit of hardware attached to the actual earpieces, the CX 400BT is very light and very comfortable. When buying this item, you’ll also get different sizes of rubber earpieces, tailoring them to your needs. You can opt to have a looser or tighter fit, but we did notice that it’s best to make sure the hardware stays in its place. It would be a shame if you lost a piece while you’re in a rush. Also, when the earbuds fit in a more ‘snug’ kind of way, you’ll experience the bass a bit better than when you opt for a size that is too small. Just like the instructions in the manual may show; when actually putting the earbuds in your ears, you’ll slightly have to twist them, in order for them to get into the right position. When they do, they are incredibly comfortable for longer periods of time.

While this would also be perfect for the overview section of our review, we decided it’s also a comfort feature. Both earbuds are completely devoid of any buttons. The shiny exterior with the Sennheiser logo on it will actually serve as a touch surface. You’ll have commands for both the left and right earpiece individually, where the left may lower the volume and the right one may raise it. The hardware will also pick up a difference between tapping the surface or keeping your finger on it, which then also triggers different functions. To adjust volume controls, like we just mentioned, you’ll have to keep your finger on the surface, while just pausing a song may require a simple tap.


  • 7 mm dynamic driver
  • Customizable touch control
  • 20 hours battery life


Having dealt with some of the functions above, there is not that much more to talk about when it comes to the CX 400BT, as it’s simply a matter of charging the earbuds and then pair them to any Bluetooth device you wish to play audio files from. The pairing goes smoothly and you’re basically up and running within moments. Like other Sennheiser products, you can download the Smart Control app to further tailor the device to your specific needs and wants, but we are still not fully convinced when it comes to this app. That being said, it does not diminish the quality of the actual device when not using the app, as its base settings are pretty much perfectly balanced already.

We took these nifty little earbuds out quite a bit for our daily commutes and, even when using them for longer periods of time, we hardly saw the battery percentage drop. While, for example, the HD 450BT headset will last a lot longer, these trinket-sized earphones made sure we didn’t have to charge them quickly. Many similar items often have you recharge them on a weekly or even daily basis if you tend to use them for longer commutes or other activities.

The audio quality is simply crisp and crystal clear. On more than one occasion we found ourselves using the CX 400BT in the comfort of our home, to watch a movie or series, while doing some light work or other activities, as the sound fidelity is quite amazing. The device made sure we wouldn’t miss a single bit of dialogue while not being able to constantly watch the screen, without having to deafen other people in the house by turning up the volume of our TV, computer, or other playback devices.


Sennheiser’s CX 400BT True Wireless earbuds are a delight to work with and the package actually comes at an affordable price. In the past, these wireless earbuds often burned a hole in your wallet, but now they often come cheaper than a premium headset. The small earbuds pack a lot of power, have deep bass, provide user comfort and the charging case is also very neatly designed. We wholeheartedly recommend this set of earbuds for your daily commute, but also for your gaming sessions and to watch your favorite series when your loved ones have given up during your binge-a-thon.

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Rating: 8.5/10 (2 votes cast)
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Rating: -1 (from 1 vote)
Sennheiser CX 400BT True Wireless - Hardware Review, 8.5 out of 10 based on 2 ratings

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