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Sennheiser CX 400BT Review: High-Quality Sound For Less

Daniel Richardson



The Sennheiser CX 400BT True Wireless earbuds are often looked at as the cheaper little brother of the Momentum 2. While this is somewhat accurate, these earbuds still have a lot to offer. 

Wireless earbuds are all the rage, and the CX 400BT TW with its 7mm dynamic drivers give the signature high-quality audio of Sennheiser at a lower price point. With this in mind, I was excited to see exactly what the earbuds could deliver. After a couple of listens to albums I am very familiar with and too embarrassed to mention, I took the earbuds for a deeper dive and began experimenting with the features. 

Sennheiser unboxingSennheiser/YouTube

To begin with, getting the CX 400BT TW working is simple from the unboxing to listening. All that’s needed is a Bluetooth connection and the earbuds to be placed firmly in your ear. There was no problem with pairing, and I was ready to begin blasting my favourite music very quickly. This Bluetooth connection also allows the user to connect to the incredibly useful Sennheiser Smart Control app, which I will touch on shortly. 

The appeal of the Sennheiser CX 400BT TW is immediately clear: it’s an unintrusive, high-quality audio experience that offers something similar to Apple’s AirPods. From the minimalist magnetic charging box to its simple bud design, there are clear comparisons to be made. Despite these similarities, the comfort of these boxy earbuds surprised me almost instantly. With a pop and a twist, they fit nicely in the ear and cause very little irritation. Of course, not everyone’s ears are the same, but in this instance, if you’re comfortable with most earbuds, the lightweight 6g earbuds will only make the experience more pleasant.

Sennheiser CX 400BT whiteSennheiser/You

The earbuds boast a frequency response of 5Hz – 21kHz, and the sound delivered is very impressive. In fact, the audio was so striking that I have ignored several conversations with housemates completely by accident. On top of that, when listening to a self-indulgent prog-rock album, I found some subtle bass notes coming to the forefront that I had previously not noticed. These earbuds deliver plenty of depth, and will definitely allow listeners to get immersed in their favourite records or podcasts. 

While these earbuds have the volume to make you completely oblivious to the complaints of others, they are not noise cancelling. If this is a key factor in the decision for new earbuds, then the Sennheiser CX 400BT TW is not for you – instead, the Momentum 2 would be a suitable alternative. However, the CX 400BT does deliver some of the best quality sounds for your money on the market. These sounds can also be tweaked to deliver exactly what you want.

Through the Sennheiser Smart Control app, you can play with the settings of the earbuds. Whether it is whacking the bass up to an uncomfortable level, or trying to find the best mix for that minimalist artist you pretend to like, the CX 400BT TW gives you the ability to customise your EQ settings when used with the app. This app also allows you to add functions, so for example, tapping the earbud three times could be used to replace a skip or pause prompt.

earbuds reviewUNILAD Tech

The earbuds are ideal for phone conversations and the clarity on both ends is good. In fact, the clarity of my dulcet tones actually took some of my friends by surprise. Receiving and rejecting calls is very simple. With standard factory settings, tapping the right earbud once allows you to accept a call and by pressing it twice you can reject it. This simplicity is consistent throughout the design and it is one of the easiest earbud systems to use and become comfortable with. Although I must confess that as a usual headphone user, I did accidentally tap and speak to Google Assistant several times in my first 10 minutes of use. 

With the current state of the world and the amount of time spent indoors, the battery life is great. However, when being on-the-move becomes easier, the earbuds may not impress long-haul listeners. At full charge, the earbuds deliver a reasonable seven hours of listening. While this isn’t game-changing, it is undoubtedly a significant chunk of the day. On top of that, there 13 hours worth of additional charging to be found through the casing. This adds up to a pretty significant amount of listening time, and if you’re like me, you rarely ignore your aforementioned housemate for that amount of time without taking the earbuds out in an act of basic courtesy. 

earbud whiteSennheiser/YouTube

Earbuds are hard to make look good – however, they can look discreet. The CX 400BT TW nails an inoffensive look that is subtle, despite not looking quite as sleek as the Momentum 2. Nonetheless, the square shape and smooth edges fit nicely without screaming that you have earbuds on. Admittedly, you won’t have many people stopping you and asking where you got your earbuds from – partly because of the logo on the side of the buds – but that is probably a good thing these days. 


The price of the earbuds will likely be the reservation of most, but in terms of earbuds in the mid-hundred range, these are some of the best in the market. With intuitive features, comfort and great sound quality, the CX 400BT truly stands on its own as a fantastic set of earbuds. After blasting everything from early 90s rap to the latest metalcore releases, these earbuds had enough quality to make me reconsider my headphones for good. While the Momentum 2 may still cast a bit of a shadow over these earbuds in terms of design, at £130 less, the CX 400BT TW is a worthwhile investment.

If the £150 earbuds get a discount this Black Friday, then they would be a fantastic purchase. 

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Topics: Technology, Headphones, Now, Review, Tech

Daniel Richardson
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