Sennheiser CX True Wireless

On the outside, these featherweight in-ears follow the slightly chunky-edged design of the CX 400BT and are made of sturdy plastic, just like their compact charging case. The in-ears are available in black or white. The construction is resistant to splashes of water and sweat, according to protection class IPX4. A touch control and a supplementary app are used to control the functions.

Practice

Although these earphones protrude significantly from the ear, they fit securely and comfortably, even during longer listening sessions as well as during sports. Four sizes of silicone fittings ensure the right fit and seal in the auditory canal. The outer insulation is quite good, and no annoying noise leaks out even at higher levels.

The battery performance is impressive: The CX True Wireless offer a practical, volume-dependent playback time of about nine hours. The charging case doubles the capacity again, giving up to 27 hours of runtime – enough for long journeys and all-day use. Multi-coloured LEDs on the charging case indicate the charging status. The Bluetooth 5.2 wireless link worked stably across several rooms in our test.

In practice, control via the touch elements is excellent, even if there are occasional errors in input. As well as the initial pairing, music playback can be started and paused, as can telephone calls. Track jumps are possible in both directions, and volume is controlled by holding the touch areas. The voice assistants Siri and Google Assistant can also be called up easily.

The earpieces function individually when needed, for example, for phone calls, and switch on and off by opening and closing the charging case. With the autocall function, phone calls can also be accepted by removing the earpieces from the case. However, Sennheiser does not automatically pause and resume music playback when the earphones are removed and inserted. Instead, there is an automatic switch-off in the event of inactivity.

The free, tastefully designed Smart Control App for iOS and Android enables comprehensive configuration of the CX True Wireless. Firmware updates (test version: 1.6.8), all touch functions and the automatic power off can be adjusted here. You can also choose between status announcements in different languages or status tones. The integrated three-band equaliser, which can be called up in two display formats, makes sense. It offers pre-sets and the ability to store your own settings. And finally, there is the so-called sidetone function, which transmits your own voice onto the headphones in three intensity levels during telephone conversations.

Sound

The CX True Wireless support the audio codecs SBC, AAC and aptX, but not higher-resolution variants. Our listening test took place with an iPhone 8 (AAC). The result is impressive, considering the target market is for mobile use. The Bass Boost noted on the packaging suggests that Sennheiser is less concerned with neutral tuning with this model; instead, they are aiming at listening fun.

The dynamic 7 mm True Response drivers deliver pressure and powerful levels. The bass reaches deep down. The tuning is rich and warm, yet contour, tone and dynamics are not lost. Only at high levels does the precision suffer slightly. However, it is clear that the bass is slightly overemphasised so that the bass perception is always dependent on the playback volume.

However, this does not mean that the mids lose anything. Distorted guitars, female and male voices and acoustic instruments are reproduced stably and with a certain warmth. Finally, the highs are finely resolved and provide the necessary percussive and spatial details of a recording. Silvery brilliance is not to be expected in this price range, but I did not notice any harshness either. I would have liked a bit more bite in the drums of some rock songs, but in other places, it was just right, for example in AC/DC’s “Fire Your Guns”. The same applies to the general tuning of a mix. As a rule, it sounds balanced and powerful. Depending on the genre and the mix, however, there may be slight imbalances due to the rich bass content. The equaliser changes little in this basic tuning, but only moderates this tendency in a sensible way. My preferred choice was a small reduction in the bass and a smaller treble boost.

By the way, it is not immediately obvious that the “Bass Boost” function can be switched in the equaliser section of the app. The effect remains rather discreet, which I quite welcome because, in my opinion, these headphones don’t need more bass.

The panning is comprehensible and provides a wide stereo stage. The spaciousness of Kraftwerk’s “Geiger Counter/Radioactivity” from the album “3-D The Catalogue” is quite impressive even on such small headphones. In summary, I would recommend these Sennheiser headphones for pop, rock and electronic music. The CX True Wireless can also handle classical and jazz music, but they lack a bit of linearity. If you are regularly out and about in noisy environments, you will benefit from the good passive attenuation of these headphones. However, as expected, this does not come close to the active noise cancelling offered by the more expensive Momentum True Wireless 2.

Finally, I would like to praise the voice quality during phone calls, because the voice is transmitted clearly and without noise. The sidetone function does what it is supposed to. However, I did not like the fading in of the external microphones, because this also made ambient sound, for example of a staircase, suddenly audible in a disturbing way.