The Sennheiser CX 400BT is priced at Rs. 16,990 in India
The CX 400BT earphones support the aptX Bluetooth codec
The earpieces look and feel good, but are quite large
These earphones are expensive, but sound quality is very good
Sennheiser launched the Momentum True Wireless 2 earphones earlier this year, which, while excellent when it comes to sound quality and features, are definitely on the expensive side at Rs. 24,990. A big reason for the high price is active noise cancellation; while this feature does contribute to the superb overall experience, it also puts the earphones out of reach for many buyers. Sennheiser's latest pair of true wireless earphones, the CX 400BT, is positioned to address that very problem.
Priced at Rs 16,990, the Sennheiser CX 400BT comes with most of what makes the Momentum True Wireless 2 so great, minus one big feature – active noise cancellation. This is a true wireless headset aimed at purists who look for good sound above everything else. It supports the aptX Bluetooth codec and has Sennheiser's signature tuning. Is this now the best pair of true wireless earphones for under Rs. 20,000? Find out in our review.
Although large and odd-looking in the ears, the Sennheiser CX 400BT is a comfortable true wireless headset
Premium build quality, but the Sennheiser CX 400BT earphones are large
Only the third pair of true wireless earphones launched by Sennheiser in India, the CX 400BT is a bit more affordable than the premium Momentum True Wireless 2 earphones. The big difference here is the lack of active noise cancellation, but the CX 400BT is a largely similar headset in all other ways, including design, build quality, and specifications.
The Sennheiser CX 400BT's earpieces look somewhat similar to the Momentum True Wireless 2 equivalents, with large solid plastic casings and a large Sennheiser logo on the outer side of each, which doubles up as a touch control panel. The earpieces are quite large, and stuck out of my ears considerably; while this didn't affect fit and comfort too much when using the right ear tips, it definitely looked a bit odd. Also worth mentioning is that there is no official water resistance rating on the Sennheiser CX 400BT, which is quite disappointing for the price.
Touch controls on the Sennheiser CX 400BT are quite easy to use, and cover all of the core functions, including playback, call handling, volume, and voice assistant access. You can customise these controls through the Sennheiser Smart Control app, as well as adjust equaliser settings and update the firmware of the headset. Although basic and not really needed for much beyond the initial setup, the app's ability to customise the touch controls could come in handy.
The charging case of the Sennheiser CX 400BT isn't too fancy, but it isn't too basic either. It has an ordinary plastic finish that matches the earpieces, and a magnetic lid that keeps it securely shut. There's a USB Type-C port for charging. This case is more functional than stylish, but that's not a bad thing. It isn't too large, and fit quite easily in my pocket. Each earbud weighs 6g, while the case weighs a reasonable 37g.
Qualcomm aptX support makes these among the best sounding true wireless earphones you can buy
For connectivity, the Sennheiser CX 400BT uses Bluetooth 5.1, with support for the SBC, AAC, and Qualcomm aptX Bluetooth codecs. The earphones use 7mm dynamic drivers and have a frequency response range of 5-21,000Hz; all of these specifications match those of the Momentum True Wireless 2 earphones, with the obvious exception of active noise cancellation.
The earphones ran for around six hours per charge at moderate to high volume levels, with the charging case providing another two full charges to the earpieces, for a total battery life of around 18 hours per charge cycle. Although the number of additional charges you can get from the case isn't exceptional, the battery life of the earpieces is pretty good compared to other options in this price segment.
Great sound quality on the Sennheiser CX 400BT
I've almost always found that advanced Bluetooth codec support goes hand-in-hand with good sound quality, and the Sennheiser CX 400BT supports that inference. The Qualcomm aptX codec makes a noticeable difference to sound quality, and the Sennheiser CX 400BT sounded great when used with an Android smartphone that was able to activate the codec. Sound quality was largely on par with that of the Sennheiser Momentum True Wireless 2, which is my current top pick for musicality among true wireless earphones.
I used the Sennheiser CX 400BT with an Android smartphone for much of this review, but also tested it with my MacBook Air and an iPad mini for reference. Although I tend to use Spotify for everyday listening, I found myself favouring Tidal's high-resolution streaming while using the Sennheiser CX 400BT, thanks to the combination of good driver tuning and technical capability.
Although the CX 400BT sounded great with any kind of music and at all volumes, using high-resolution tracks and turning the volume up to around 90 percent brought out the absolute best in these earphones. Listening to Bruno Mars' Chunky and Ain't No Mountain High Enough by Marvin Gaye on Tidal Masters was an incredibly enjoyable experience, with the earphones bringing out oodles of detail in the tracks. Even the faintest elements in the beat of Chunky felt real and present, while Gaye's voice sounded clean and full of character.
Battery life is decent, with around six hours of listening per charge on the earpieces
Like the Momentum True Wireless 2, the Sennheiser CX 400BT's sonic signature definitely has some flavour to it, and isn't as balanced or flat as what you'd get with some other options such as the Lypertek Tevi. Instead, you get punchy lows that really drive up the energy level, all while remaining refined and controlled enough to not sound too boomy.
While the aptX Bluetooth codec helped bring out detail and refinement in high-resolution music, this didn't necessarily mean that compressed audio sounded poor. The Sennheiser CX 400BT sounded a little more aggressive and forceful with Spotify and YouTube Music, but never unpleasant. The earphones' flexible nature also meant that pretty much any genre sounded good, although the bias towards the lows made for more entertaining sound with fast-paced electronic audio tracks.
Listening to Inside My Head (Aeroplane Remix) by Riton, the sound was engaging and immersive, with the low-end for me being felt more than heard. The mid-range and highs were also clean and quite natural, but the overall sonic signature was heavily defined by the low-end drive. Although a lot of listeners might prefer a more natural-sounding pair of earphones, this dash of flavour and character is what made the Sennheiser CX 400BT all the more endearing to me.
The earphones did also work well enough for general audio, including watching videos and voice calls. Premium options from Sony, Apple, and Jabra are a bit better for voice calls, but the Sennheiser CX 400BT does a reasonable job, with acceptable sound on both ends of the call. The lack of features such as active or environmental noise cancellation are the differentiating factor here, with the Sennheiser CX 400BT being more focused on music.
Sennheiser's presence in the premium true wireless space has so far been limited to the flagship Momentum True Wireless range, so the CX 400BT comes as a welcome addition to the sub-Rs. 20,000 price segment. With largely the same performance as the Momentum True Wireless 2 when it comes to sound quality and battery life, this is a worthwhile headset to consider, assuming you don't need active noise cancellation.
The most musical of all the true wireless earphones I've reviewed in this price segment, the Sennheiser CX 400BT is ideal for buyers who value sound quality and performance with music above all else. If you want active noise cancellation at around this price, options such as the Jabra Elite 75t and Sony WF-1000XM3 are also worth considering.
Ali Pardiwala writes about entertainment, auto, audio, video, and more for Gadgets 360 out of Mumbai, and has covered the industry for over a decade now. Although originally a reviewer focused on audio and television products, he has since transitioned to covering a wide variety of topics. He is a firm believer in 4K and HDR on televisions, and believes that true wireless earphones are the future of the personal audio industry. Ali is available on Twitter as @AliusPardius and on