Sennheiser CX 400BT True Wireless

Designed to be a more affordable ‘everyday’ alternative to Sennheiser’s Momentum range, the CX 400BT True Wireless hasn’t made too many compromises to bring the price down. The design is similar to the Momentum 2 (HFC 410) and is available in black or white with a rather chunky earpiece that protrudes quite noticeably from the ear. I always seem to have trouble getting earbuds to stay in my ears, but Sennheiser provides four sizes of eartips to help create a good fit.

Internally, the in-ear uses the same 7mm drivers as the Momentum 2, and shares the same 5Hz-21kHz frequency response, which is quite impressive at the price. It supports both aptX and AAC codecs for Bluetooth, making it suitable for a wide variety of Android and Apple devices. There are some cost-cutting measures, however, with the active noise-cancellation of the Momentum 2 absent. Battery life is around seven hours on a full charge – the same as the Momentum 2 – and the compact charging case lets you top up the battery for 20 hours of use, compared with the 28 hours of the Momentum 2. The case has a USB-C connector for charging its internal battery, although Sennheiser provides an adaptor cable for older devices that still use USB-A.

The outer surface of each earbud acts as a multi-function button that can perform a number of different tasks, so you can find yourself randomly tapping the outer shell as you try to remember the various commands. Sennheiser’s Smart Control app allows you to re-program the buttons to make them easier to use and also provides equaliser controls for fine-tuning the sound.

Sound quality
Intrigued by the claimed 5Hz-21kHz frequency response, we begin by delving into the electronic depths of Max Richter’s Shadow Journal, stored as a lossless AAC on an iPad. Many Bluetooth headphones struggle with this track, but the CX 400BT makes a good start, thanks to its support for the AAC codec. Instead of the confined sound that is often associated with Bluetooth, the in-ear is able to conjure up a dramatic, open sense of space for Richter’s soundscape, allowing the electronic loops to swirl lightly through the air. There’s a sharp, mournful edge to the violins and then the deep electronic bass effects begin to rumble below, like a thunderstorm echoing away into the distance.

That sense of space is also evident on My Lagan Love by Kate Bush, again in AAC format. There’s a haunting melancholy to her a capella vocal as her voice seems to pierce the autumn gloom all around – “When rainy nights are soft with tears, and autumn leaves are falling”. And the CX 400BT handles Bush’s voice with the same ease as Richter’s bass, capturing its dramatic emotion without any hint of harshness on the soaring high notes.

Even the sonic overkill of Muse doesn’t faze the CX 400BT, as the MQA version of Supermassive Black Hole kicks in from the Tidal streaming service. The grinding guitar and bass riffs are drenched in fuzz, but the CX 400BT is able to keep them clear and distinct, avoiding any distortion and even leaving some room for the lightly brushed percussion to lay down the tempo and hold everything together. And, again, the overall balance of the sound is impressive, as Matt Bellamy’s falsetto weaves its sinuous path through the noise without being overwhelmed by the deep, chugging bass beneath it.

A little more raw volume wouldn’t go amiss, so the Sennheiser might not be the best choice if you’re after some loud, motivational exercise music. Regardless, it provides an impressive performance from a set of earbuds in this price range, meaning the CX 400BT is a great choice for relaxing and listening to music indoors or during a quiet stroll. CJ    

Product: Sennheiser CX 400BT True Wireless
Type: Wireless in-ear earbuds

●  7mm dynamic driver
●  20-hour battery
●  Charging case

Read the full review in  Issue 472

Sennheiser UK