Closer Examination

In the absence of any cables, the storage case included with TWS earphones is important since it is also responsible for charging the earphones. Sennheiser has color-matched cases for the CX TWS, with this black set coming with a black plastic case. It's also on the smaller side to where this is fairly pocketable; however, the rectangular cuboid form factor doesn't make it easy. Branding comes in the form of the Sennheiser logo on the top, with a carved notch going all around the sides for opening the case, and an indicator LED below. Wired charging happens via the Type-C port on the back, which is below a flush hinge used to keep the case clean without anything jutting out to potentially snag on objects. Certification information and the full CX200TW model name are on the bottom.


The case has a 400 mAh battery inside, which is below average for TWS earphones. The individual earphones have a 60 mAh battery inside, so the case can provide around three charge cycles with efficiency losses accounted for. Sennheiser is conservative with its own rating though, mentioning 9 hours per charge cycle and 27 hours in total, which is two charge cycles from the case. In practice, it is closer to three, which is good news as the size of the case would have been a letdown at just two cycles and no wireless charging options.

Charging the case is slow and steady with standard 1 A over 5 V, which corresponds to ~1.5 hours from 0–100%. The indicator LED uses red, yellow, and green with both flashing and solid states to indicate various battery phases when charging and discharging, and the manual does a good job of describing this more varied approach compared to most such cases. Opening the case reveals the earphones inside, fully charged and ready to be used. Notice the matching compartments with magnetic pins in the case to securely hold and charge the earphones while in the case, as well as the Sennheiser marking and large magnet to keep the case closed. The case takes ~1.5 hours to fully charge the earphones, and there is fast charging (15 min = 1 hour playback), so these rated numbers are still decent in practice.


Be sure to peel off the plastic tags on the magnetic pins of the earphones so they can be charged in the case, and notice the indicator LEDs placed on the bottom. This means the earphones by themselves don't easily show whether they are paired or fully charged when in the case, instead relying on a combination of the case and voice prompts to do so. When set to pairing mode, either automatically the first time around or manually, the LEDs flash red and blue before finally settling on one color for a few seconds before turning off. Sennheiser continues the plastic construction here, and these are denser than others for their size at ~6 g each. I think this black set is quite clean to look at, with the single glossy trim on the shells matching the design language on the case as well.


The face plate, if you will, houses the capacitive touch sensor for the touch controls, and it has a flat surface to where the glossier logo identifies the region when installed. The rest of the face plate has a matte finish, and the shells are not dust magnets by any means. A vent on the cover and another on the side provide access to the microphones for voice communication and help with airflow through the acoustic chamber. The inner surface touching the ear concha has the magnetic pins for charging the internal battery, L/R markings to indicate the left and right channels, and aforementioned indicator LED. Removing the pre-installed size M ear tips shows a small nozzle with an integrated notch at the end that secures the ear tip, as well as a mesh filter on the end to prevent contaminants from entering the acoustic chamber.