Sennheiser CX 400BT True Wireless Earbuds review

Sennheiser CX 400BT TWS review

No, this is not your affordable TWS but these are definitely affordable Sennheiser buds that offer their typical sound signatures. The company’s Momentum 2 TWS which I had reviewed earlier, continues to be one of the best pair of TWS earphone I enjoy. Will Sennheiser CX 400BT tws offer the same level of audio signature let’s find out in this review.

To begin on a lighter note, I would have appreciated if Sennheiser would have chosen a nicer compelling name like Momentum for the younger sibling rather than an alphanumeric naming – CX 400BT.

Design and Build Quality of CX 400BT

One of the key highlights of the Momentum True Wireless 2 (including their first gen) was their pleasant, nice looking fabric lined case. It instantly hits a premium note to the product. That visual vibe is missing with the CX 400BT where they have opted for a more generic plastic case. It is available in both black and white color options. It measures 59 x 33.8 x 42.3 mm and weighs 49 grams with the buds. It is noticeably smaller and slightly taller than the Momentum case but compact.

Top of the lid has the Sennheiser logo engraved. The back of the case has a USB type-C port, a pairing and status button and a lone LED indicator for charging and battery status.

Coming to the design of the buds, the Momentum TWS 2 had a prominent circular design, the CX 400BT features a rectangular design with rounded corners. They are still a bit chunky, though at 6gms they are lightweight. When you wear it, they would be still noticeable on your ears. It fits well into the ear and remain secure and comfortable.

Controls on CX 400BT

The buds has a capacitive touch surface and worked to be simple and responsive to use. You can play / pause, answer / end / reject calls. You can also change tracks to next or previous by double tapping either the left or right earbuds. Long press on either buds controls the volume up or down. Triple tap launches the voice assistant on your phone. The controls are smooth to use.

You can also rearrange the touch controls in the Sennheiser “Smart Control App”. You can also play around with the EQ settings in the app.

Sound quality of Sennheiser CX 400BT TWS

While they might have compromised on the look and feel of the case and buds, the Sennheiser did not compromise much on the awesome sound quality we get in Momentum 2 TWS. They state a frequency response of 5Hz- 21,000 Hz. The supported codecs and profiles are SBC, AAC, aptX™ and A2DP, AVRCP, HSP, HFP via Bluetooth 5.1 retaining the same 7mm dynamic drivers.

It offers a very commendable space and instrument separation. Sennheiser again demonstrates their superiority in handling a prominent bass without damaging the mids and trebles. You get every detail without bass overbearing on the rest. In short, the listening on this pair of earbuds is an enjoyable and gratifying experience for an audiophile. A b it on the call quality, it is something you can manage through the calls. No one complained about any poor call issues while I spoke to them.

The CX 400BT misses out on the ANC and Transparent Hearing which the Momentum 2 TWS offered but that is a compromise you make for the slightly lower pricing of the CX 400BT. It also lacks any water or sweat resistance, which I feel Sennheiser should have offered some sorts for this price. Though it should not matter if you use using it for your regular work or walk but not sure how the lack of sweat resistance will matter if you really sweat out in sun or in workouts.

There is no wear detection, a feature I like to in TWS earbuds. So if you take out the buds from the ear, it doesn’t pause the music. You can use the right buds as stand alone with the other bud in the case, so essentially the right earbud is the “master” and the left is dependent on it.

Battery life

Sennheiser claims a total of 20 hours of battery life including both the case and earbuds with earbuds offering seven hours of battery life per charge. In my test it almost covered 7 hours. It is a good duration for an average listening in one go and we would rarely use it on a 7 hour stretch without keeping in in case. So battery life is satisfactory.


Pros: What works for Sennheiser CX 400BT

  • Great Sound
  • Appreciable sound staging
  • Decent battery life
  • Codec supports
  • Customizable controls
  • Responsive controls
  • Comfortable to wear
  • Stable connection

Cons: What doesn’t work for Sennheiser CX 400BT

  • No ANC or transparent hearing
  • No wireless charging
  • No wear detection
  • No splash proof

 On a final note, if you are an audiophile, the Sennheiser CX 400BT would definitely excite you for its stellar almost well tuned audio profile. It might lack few extra add-ons, but when it comes to audio signature, it is almost closer to the Momentum 2 TWS.

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