TWS true wireless earphones - under $100
FIVE STARS - Now available at 100 dollars, the Sennheiser CX 400BT is one of the best sounding wireless earphones this money can buy.
Sennheiser CX 400BT specs:
Bluetooth 5.0 with AptX and AAC codec
7 hours listening on a full charge
Charging case can charge earpieces fully 3 times
Comes with 4 sizes ear tips and USB-C cable
$99 on Amazon US, Amazon Germany or from other Amazon countries
Below this Sennheiser CX 400BT 2021 review, you will find comparisons between the Sennheiser CX 400BT vs Fiil T1 Lite, Samsung Galaxy Buds Plus, Soundcore Liberty Air 2 Pro and Liberfeel x Edifier Uni-Buds.
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Design, comfort and battery life
The Sennheiser CX 400BT cost 200 dollars upon release, and the sound quality has been praised around the net. With the price slashed in half, it must certainly be an incredible deal, right? Well - the Sennheiser enters 2021 and different territory now. The excellent Samsung Galaxy Buds Plus is now even cheaper and the Soundcore Liberty Air 2 Pro even throws in great active noise cancellation at the price point. And then there's wonderful budget treats like the Liberfeel x Edifier Uni-Buds or the $35 Fiil T1 Lite. How does the Sennheiser stack up against these?
Sadly, there's not much premium brand-sensation going on with the CX 400BT. Apart from the big Sennheiser S-logo in the earbuds, it looks like it could have cost 40 bucks too. The case has some decent weight but is also rather big, and the material scratches way too easily. There's only a single LED-light that indicates the charging status - it fires by pressing the button next to it and doesn't show it's empty by itself.
The earbuds, too, are bulkier than most competitors. For earphones without stems, they protrude out of your ears just a tiny a bit. The square design makes it easy to feel the difference between the side with the touch panel and the other sides.
Yet - even though its earpieces are big, the CX 400BT is comfortable to wear. The inside of the earbuds is ovally shaped, and a slight bump follows the shape of your ears. You can always feel these when you're wearing them - but they have a snug fit and stay put in your ears. Unfortunately - they don't have a waterproof rating.
The Sennheiser CX 400BT has above-average battery life; it can reach up to 7 hours of playtime on a single charge, and the case can nearly recharge it fully twice before needing new power via USB-C itself.
Connectivity and controls
Connectivity on the Sennheiser CX 400BT is mostly good. It has a stable Bluetooth connection up to ten meters away from your device, also in areas crowded with wireless signals. It's impossible to switch between listening to one or two earbuds seamlessly: put the right bud in the case, and both shut off. Pretty much every $20 new wireless earphone does this better.
Due to the buds' square shape, it's easy to find and control the touch panels. Single taps are supported but require a lengthy tap, eliminating accidental touches. The control scheme is straightforward and good:
Tap L or R to play/ pause
Hold R to increase the volume
Hold L to decrease volume
Double-tap R to skip a song
Double-tap L to return a track
Triple-tap L to activate the voice assistant
What's more, is that these controls have a certain build-up. For instance, the double-tap requires a little bit of waiting between the first and the second tap. The Sennheiser affirms every touch with a gentle beep, and in the case of the double-tap, it's always a lower beep first and a slightly higher beep after the second tap. The CX400 responds quickly enough, so it doesn't become annoying. It actually feels reliable - you always know what command you're activating.
The earphones don't have auto-pausing by taking an earphone out, but all the controls are right on your fingertips and work like a charm.
Calling and watching movies
It's very doable to take a phone call with the Sennheiser CX 400BT. Your voice sounds a little tinny and can strike as if you're talking into a pillow a bit and surrounding noises could have been reduced more as well; the other end o the line can identify a passing car, people talking, or a car passing by. However: your voice is loud enough, making you audible under all these circumstances.
The CX 400BT handles video calls great. The volume in your voice tops that of many other wireless earphones, and while your output won't be the most detailed, you sound clear.
Unfortunately, watching videos comes with strange problems. The audio isn't always in sync with video on apps like YouTube, Netflix, Amazon Prime, and Disney+. It may require pausing and playing a couple of times before the Sennheiser grabs all in sync on both Android and iPhone. The CX 400BT is one of the few earbuds encountering this. Sennheiser didn't respond if there will be a firmware update to address this.
Like on almost all wireless earbuds, there's a heavy delay in sound effects when you're playing games.
App support of Sennheiser CX 400BT
The CX 400BT enjoys support from Sennheiser's app, which is free to install and use, doesn't require an account, and works well on both Android and iPhone. The app provides the following functions:
Update the firmware from the earbuds
See and manage a list of the different devices the earbuds have established Bluetooth connections with (unfortunately, this doesn't mean the Sennheiser can automatically switch from one device to another)
Change the controls
Change the sound by drag a line that balances out bass and treble automatically
Change the sound by creating your own equalizer by adjusting frequency bands
Save equalizer presets
Change the controls to your liking
No multipoint connection; but there is a list of devices
This line-equalizer doesn't work too well
The control options from the Sennheiser app work great. The option to change the sound by dragging a line, not so much: it's a way to let more treble or bass in - but probably not a way to improve the overall sound. It's easier to tune the sound by the band-equalizer, yet as you can read in the sound part of the review - it may not be necessary.
Also read: The best wireless earbuds under $100
Sound quality of Sennheiser CX 400BT: Lovely
Now for the best part: the Sennheiser CX 400BT sound quality.
The CX400BT has a warm sound. To thank mostly, are the boosted lower mid-tones. Drums are well emphasized, and their strikes have a hefty yet controlled impact. In dance and other non-acoustic genres, darker electronic tones are prominent and provide music with a generous flow. It intertwines with the bass. The mid-bass delivers a steady, subtle thump that doesn't force itself in songs where it doesn't belong. The sub-bass isn't the tightest, yet it can ignite a sweet rumble, and bass notes can sound lovely deep.
This elevation of lower frequencies usually has the same effect: it makes music sound warm and full. So full, it can become crowded - especially darker male vocals can drown in the lower areas of the music.
But not this time. This is a Sennheiser, and Sennheiser knows vocals.
The vocal performance sets the CX 400BT apart from its competitors, both cheaper and more expensive. It's exquisite. From the lowest near throat-scraping depths of Leonard Cohen to the shrill stabs in Björk's voice: the Sennheiser presents vocals center stage. They are upfront, remarkably more prominent than instruments. They're powerful and come with great detail, but at the same time, there's not a single moment where they become too much. This Sennheiser masters the higher notes. There's enough room to breathe, but not a single vocal outburst, not a single cymbal, enters harsh territories. Music is never too sharp or bright.
What's more, is that vocals are literally center stage. Whatever track, genre or recording quality you're throwing at them, singers are always right in front of you. Sometimes as if you're nearly mouth-to-mouth. Like Sennheisers praised headphones HD58X Jubilee and HD600, the CX 400BT has an impressive and intimate soundstage, wherein instruments resolve around the center vocalist, sounding all around you, with plenty of space - yet closeby.
It's remarkable how good mid-instruments like guitars, piano play, and trumpets are represented in a sound that's both so full yet vocal-centered. While they never play the biggest role, it's easy to pick up details like the plucking of guitar strings or resonating of snare drums. Like darker instruments, they sound natural and textured, even though they bear a strong warm undertone.
Things come together in the Sennheiser CX 400BT. It sounds warm, smooth, detailed, and pronounced all at the same time. It doesn't get much lovelier in wireless earphones.
Sennheiser CX 400BT comparisons
Sennheiser CX 400BT vs Fiil T1 Lite
It's smoothness that separates the $100 Sennheiser CX 400BT from the brilliant $35 Fiil T1 Lite. The T1 Lite has a stronger mid-bass thump and elevates (upper) mid-tones more, giving guitars, cymbals and vocals more detail on the top end, but also making them reach harsh territory sometimes. Vocals on the T1 Lite can be explosive, whereas they are more controlled on the CX400BT, which also has a warmer tone and more intimate setting. The Fiil has a less focused soundstage, with more details coming from your wide-left and right. Function-wise, the Sennheiser has slightly better battery life, controls, and (video) call quality, but the Fiil is more comfortable and has an even harder-to-beat value for money.
Fiil T1 Lite review ($35)
Fiil T1 Pro review ($65, adds ear wings and ANC noise cancelling, slightly more upper-mid emphasis)
Sennheiser CX 400BT vs Samsung Galaxy Buds+
Switching back and forth between the now equally expensive CX 400BT and Samsung Galaxy Buds Plus requires adjustment to the sound every time. The latter has a much brighter sound, with more extended upper-mids and highs. Vocals and instruments have an edge on the higher tones, but don't always come with the same body in the lower ones. The Sennheiser restricts the higher notes more and boosts lower-mids into the sound instead; it's the (under)representation of these tones that can make the Samsung sound thin in comparison. Mid-bass on the Samsung is quick and functional; thicker and warmer on the Sennheiser. The subtle sub-bass of the Samsung makes every strike count; the Sennheisers is more giving. The Buds Plus is a step up in build quality, battery life (11 hours!), and app support; but ultimately, the Sennheiser is a more pleasant listen.
Samsung Galaxy Buds Plus review ($80-100)
Sennheiser CX 400BT vs Edifier Uni-buds
The Liberfeel x Edifier Uni-Buds has more extended upper-mids and highs, creating a brighter sound with sometimes thinner, more intrusive vocals than the Sennheiser CX 400BT. Cymbals, high-hats, guitars, trumpets, and violins all sound more upfront on the Edifier, supported by a fatter mid-bass and better-separated sub-bass. The Sennheiser has a smaller soundstage, warmer, smoother, and more intimate sound; it keeps vocals better in control - preventing them from sounding thin. The CX400 is more background listening-friendly than the Edifier. The Sennheiser wins in call quality; the Uni-Buds have better battery life and comfort.
Liberfeel x Edifier Uni-Buds review ($65-75)
Sennheiser CX 400BT vs Soundcore Liberty Air 2 Pro
Recently awarded 5 stars on Scarbir.com, the Soundcore Liberty Air 2 Pro throws in good active noise cancelling around the same price as the CX 400BT. It also has a more extensive app, with more usable equalizers, noise cancelling-settings, and a (below-average) Ambient Mode. On sound quality, however, the Sennheiser just does things better out of the box. The CX 400BT has more pronounced and attractive vocals, resolves more detail in the mid and higher tones, and sounds less crammed in the higher frequencies. It also has a more natural and well-placed soundstage. The Soundcore does have great equalization options, however - so if you desire noise cancelling, it's well worth considering still.
Soundcore Liberty Air 2 Pro review ($100-130)
Sennheiser CX 400BT vs Omthing Airfree
Loving warm sound with deep bass notes? The $25-$50 Omthing Airfree (also sold as 1more Pistonbuds) may be a terrific cheaper alternative. You will still have good (video) call quality and comfort, although its battery life is noticeably less and only lasts 3,5 hours per charge. In sound, the Omthing has a more prominent bass, with a fuller mid-bass and stronger sub-bass notes, which can sound deeper and more engaging in more acoustic genres, such as jazz and blues. It doesn't forward vocals that much, however, giving the Omthing a slightly dark sound - precisely the point where the Sennheiser takes it up a notch and sounds more vivid, pronounced, and detailed.
Omthing Airfree/ 1more Pistonbuds review ($25-$50)
Verdict
With the initial price cut in half, the Sennheiser CX 400BT truly is an outstanding buy. Its good battery life and (video) call quality make it a solid choice for everyday use, and the sound is a warm blanket you'll like to dive under time and time again.
FIVE stars - excellent
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