Sennheiser released the CX 400BT True Wireless not long ago. What does Sennheiser provide and how do these earphones sound? In this review, I will find out!
Since there is a good video online about the construction of the earphones, I will put it here too! 🙂
First, of course, we start with the specifications.
Dimensions: 59 x 33.8 x 42.3 mm (earphones and charging case)
Weight: 49 g (earphones and charging case) 6 g (one earphone) 37 g (charging case)
Package dimensions: (L x W x H) 170 x 115 x 47 mm
THD, total harmonic distortion: <0.08% (1 kHz / 94 dB)
USB Standard: USB-C
Warranty: 2 years
Frequency Response (Microphone): 100 Hz to 10 kHz
Bluetooth Version: Bluetooth 5.1 compatible
Supported Profiles: A2DP, AVRCP, HSP, HFP
Frequency Response: 5 – 21,000 Hz
Ear coupling: In-ear, closed acoustics
Charging time: 1.5 hours to fully charge / 10 min. for 1 hour of playback time
Power supply: 5 V⎓ 600 mA max
Battery specification: Built-in rechargeable lithium ion batteries
Codec: SBC, AAC, aptX™
Battery time: Up to 7 hours of playback with the earphones, up to 20 hours of playback with the charging case
App support: Sennheiser Smart Control app for iOS™ and Android™
Speaker type: Dynamic 7mm Sennheiser driver
CX 400BT True Wireless Earphones
Set of ear adapters in silicone (XS, S, M, L)
Quick Start Guide and Safety Guide
Through Sennheiser, I received the new Sennheiser Momentum True Wireless 2 and the CX 400BT True Wireless. This review is of course about the latter.
Sennheiser supplies quite a bit with the CX400BT True Wireless, namely:
– XS, S, M, and L silicone adapters to adjust the in-ears to your liking
– USB-C cable to charge the case.
– Of course the case and earphones.
What I find a bit unfortunate is that the USB cable is so short (25cm from end to end).
The case of the CX 400BT looks fine. In my opinion, it looks ‘a bit’ cheaper than the True Wireless 2, which has a fabric finish.
The CX 400BT is higher but otherwise smaller than the True Wireless 2 case.
The underside is not very exciting. Still, I include it for the curious among us! 😛
On the back of the case is the USB-C connector that can be used to charge the case. The little button next to it can activate the charging function – if this is not done automatically.
There is a small LED on the back (left of the USB-C connector) that blinks orange when the case is being charged and turns green when it is fully charged.
The CX 400BT has two small holes in each earphone which serve as an opening for acoustic optimization. The right side also has a speech microphone in the earphone.
During a call, I can be clearly heard, provided you walk against the wind. But this is also true when calling from a phone against the wind – then you can’t be heard either.
The two pins charge the headphones, and the two larger spots – per ear – hold them magnetically. And pretty well, too. Whether you move back and forth quite a bit, the earphones stay in place just fine.
The software is easy to use. The most important things come up; battery life and EQ.
That is actually all you want to be able to see or control with the earphones. The EQ is very easy to work with – just slide the pointer to more/less bass or treble and enjoy the adjustments right away. This way, the earphones are really customizable.
Through Google Play and the App Store, you can download the Smart Control app to control the earphones.
It’s an easy process. Pairing the earphones via Bluetooth and opening the app worked best for me.
Why this appears in the menu, while the earphones are already paired, is a mystery to me.
What is nice is that each earpiece has its options, which can be operated with a light touch.
It is clear that it is fun to use the touch control. But the fact that you can also adjust it is of course completely epic!
The app checks for software updates when opened (this can also be checked manually via the menu at the top right).
You can easily influence the EQ of the CX 400BT True Wireless via the Smart Control App. When it is in the middle, it is ‘normal’ or off. By influencing the slider, the sound is affected. If you shift more to the left, the bass will come out more. Central is fine for these earphones in my opinion!
Of course, there is also the option to save the presets yourself and to easily select them afterwards.
Through the settings, the earphones can be further customized.
The settings of the app can be adjusted via the app setting.
The ears are not only available in white, but also in black. And that one I find more beautiful but also quieter looking.
Making calls is fine with both the Sennheiser CX 400BT True Wireless and the Sennheiser Momentum True Wireless 2. The other party could hear me clearly. When I asked my wife to put in the earphones and call me, I also experienced the same thing. The CX 400BT is simply very clear!
Active Noise Canceling
The Sennheiser CX 400BT True Wireless does not have Active Noise Cancelling. This explains the price of course.
The Momentum True Wireless 2, however, does have this. It also has Transparent Hearing. The CX 400BT does not have both.
What strikes me personally is that for me it is noticeably no different in terms of audio quality from the Sennheiser True Wireless 1, the previous generation
One of the first songs I accidentally heard through True Wireless was Dusky – Staunch (KETTAMA Remix). At first, I didn’t realize anything during the first few seconds until the drop fell. My first reaction was “holy moly what a sound”. And before you knew it, a battery charge was over, through both heavy songs like the ones below, to quiet classic tracks.
For the songs below, I turned off the presets to hear how the Sennheiser CX 400BT True Wireless sounds.
Gregory Porter, how the man can sing! The Claptone Remix sounds to me with the True Wireless just as Claptone would have intended. The instruments come out wonderfully in combination with the lows and vocals.
A little something different. While typing this review, I have “Charlotte de Witte ‘New Form’ I” on in the background. Not only is it a very fine mix, but the CX 400BT also lets it come through ‘wonderfully’. The bass is nicely present and during the song, with vocals, it comes through perfectly. It’s like standing next to the KRK speakers. With such songs, I am genuinely positively surprised with such in-ears.
That’s how reviewing sometimes feels like “nobody said it was easy”. Let’s move on to another hard track that is a lot of fun to listen to. Even now (when I hear this song for the umpteenth time in a short time) I have a smile on my face again.
I often add the number below in my reviews. Not because I don’t know more songs, but because I can enjoy this one immensely. Even though the song on YouTube in this case is not very great. It’s a beautiful song to listen to.
The deep voices of Pavarotti and James Brown are perfectly rendered.
Tip: the CD Pavarotti – The Greatest Hits has this song in higher quality! 😉
Metallica also listens wonderfully. I honestly notice, even with older songs that may be a bit lower in quality… it just sounds very clear when there is singing, instruments also come through clearly.
And I think that’s pretty good, such sound for such small earphones.
Closing with Above & Beyond, holy moly… Feelings all around! What a beautiful song! Especially how the Sennheiser CX 400BT True Wireless reflects this.
It sounds very full, and clear. Vocals by Zoë Johnston sound really beautiful with these earphones. The beat is great again. All in all… enjoy!
In summary, in terms of music, the CX 400BT True Wireless – just like the True Wireless 2 – gives a very good feeling. The lows are lovely. Highs sound wonderful when listening to beautiful vocal songs and the mids are spot-on with every song in my opinion! If the bass is too high or too low for you, you can still adjust it via the app.
Headbanging or not, Sennheiser has once again released in-ears that last for hours in addition to the True Wireless 2 with the CX 400BT.
The great thing about these earphones is that they can stay in place for hours. And if they don’t fit snugly enough, you can adjust the silicone caps to a larger/smaller size.
For fairly small earphones like the Momentum True Wireless 2, I am quite impressed with the battery life. With about 7 hours of playing time and to charge for another 13 hours via the case, you can move forward with the CX 400BT! The True Wireless 2 can last a little longer with 28 hours in total.
The in-ears stay in place perfectly and don’t feel irritating. After all, they are also very light, and that makes a difference!
It is also an advantage that Sennheiser provides different silicone adapters so that the right size can always be found.
Compared to the B&O E8 (which I was able to review earlier), I am impressed with the Sennheiser CX 400BT. In fact, I personally like this one a lot better than the E8.
In terms of sound, I feel there is more character, but also more sound from the CX 400BT.
The advantage of this Sennheiser CX 400BT True Wireless is that it can also be operated via the app. If it has too much bass, it can be reduced by a simple adjustment – and vice versa!
During the review, I switched from a lot of different genres. Trance, techno to classical, or hardstyle can be played with great pleasure.
If you are looking for a set of more luxurious earphones with a lot of options – and a reasonable battery life, then I would definitely give the Sennheiser CX 400BT a try. If you want to spend a little more and go straight for ANC (Active Noise Cancelling) as well as Transparent Hearing, then you should look at the Sennheiser Momentum True Wireless 2.
The True Wireless 2 remains a deserved winner in my opinion!
That’s why the CX 400BT True Wireless deserves 4 out of 5 stars at the price of 200 euros in my opinion.
Edit: In the meantime, the earphones have dropped to 130 euros, which in my opinion is really a hoot at a price for these earphones. In my opinion, the CX 400BT, therefore, deserves an extra point and gets 5 stars anyway!