Sennheiser CX 400BT Specifications, Tests and Review

Headphone type
In-ear
Connectivity
Wireless
Frequency Response
5 - 21000 Hz

A detailed list of technical data, specifications, ratings and expert review of Sennheiser CX 400BT. Get a comprehensive look at your chosen headphones and see if these are the ones that will best suit your needs. You can also use the comparison feature to compare with other competing headphones.

DESIGN AND DIMENSIONS Sennheiser CX 400BT
Product Type True wireless earphones - Bluetooth - wireless
Dimensions & Weight Details Earbud: 6 g
Charging case: 37 g
Colour White | Black
Recommended Use Portable electronics

The Sennheiser CX 400BT are wireless headphones that allow unrestricted movement and thus increase comfort while listening to music. Because of this feature wireless headphones are especially popular with casual users. On the other hand, the limiting factor of wireless headphones is a certain delay in sound transmission between the source and the headphones (almost indistinguishable for the average user), and they also need to be charged regularly. Unlike wired headphones, where the headphones are charged by the connected cable itself, wireless ones must be charged separately. The technology used for the sound transmission used by the headphones is Bluetooth 5.1.

These headphones are in-ear type and are therefore designed to fit directly into the ear. This allows them complete or at least partial isolation from external noise. Such headphones may also have an ambient sound isolation function, which affects the degree of their isolation capabilities. Compared to over-the-head headphones, in-ear headphones are much more portable

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SOUND QUALITY Sennheiser CX 400BT
Headphones Form Factor In-ear
Headphones Technology Dynamic
Connectivity Technology Wireless
Wireless Technology Bluetooth
Bluetooth Version Bluetooth 5.1 Better than 90 % of in-ear headphones rated.
Bluetooth Profiles Hands-Free Profile (HFP), Headset Profile (HSP), Advanced Audio Distribution Profile (A2DP), Audio/Video Remote Control Profile (AVRCP)
Bluetooth Audio Codec SBC, AAC, aptX
Sound Output Mode Stereo
Frequency Response 5 - 21000 Hz Better than 65 % of in-ear headphones rated.
Total Harmonic Distortion (THD) 0.08% Better than 97 % of in-ear headphones rated.
Max Sound Pressure 107 dB
Diaphragm 7 mm Worse than 90 % of in-ear headphones rated.

The sound quality can be affected by many factors. For many users the frequency range is a key feature of headphones. The wider the range, the more detail and nuance you will hear while listening. However, every individual perceives frequencies differently, so the frequency range of headphones varies according to individual needs. The average person perceives frequencies in the range of 16 to 20,000 Hz, so headphones with a frequency range of 20 to 20,000 Hz are most commonly available. If you are looking for headphones with a good bass performance, you should aim for lower range values (bass represents frequencies up to about 256 Hz), while high range values (frequencies roughly above 2,048 Hz) will be better for reproducing high tones. The frequency range of headphones Sennheiser CX 400BT is 5 - 21000 Hz. Overall, these headphones can reproduce sound up to 107 dB. However, be careful. Repeatedly playing music continuously at really high volumes can damage your hearing.

Headphones consist of many important parts, including the diaphragm, which is responsible for converting electrical signals into sound. The diaphragm, with a thickness of around 6 mm, is very sensitive to changes in high frequencies but less sensitive to bass. For a relatively balanced sound profile, a medium-thick diaphragm of around 10 mm is used, which can reproduce both bass and treble. A diaphragm with a thickness of around 20 mm is not as quick to respond to changes in the audio signal, and this results in poorer bass listening. However, it is very sensitive to higher frequencies. In the case of this model, the diaphragm is the 7 mm. Total harmonic distortion is one of the parameters you will come across and usually includes the average value of the distortion when reproducing all frequency bands. This parameter is not critical when choosing headphones, but it is important to remember that higher harmonic distortion can negatively affect sound quality. In case of these headphones, the total harmonic distortion is Audio Output | Total Harmonic Distortion.

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MICROPHONE Sennheiser CX 400BT
Form Factor Built-in
REMOTE CONTROL Sennheiser CX 400BT
Controls Volume control, answer/end, play/pause, next/previous track, reject call, pair mode, voice assistant, equaliser preset
CABLE Sennheiser CX 400BT
Cable Type USB-C to USB-A cable - detachable - straight - 25 cm
FEATURES Sennheiser CX 400BT
Features Voice alerts, touch control
Intelligent Assistant Siri, Google Assistant

Demanding users and technology enthusiasts will appreciate an intelligent assistant with whom they can partially control connected devices. For example, they can adjust the volume or request information about messages or alerts.

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BATTERY AND CHARGING Sennheiser CX 400BT
Battery Type Headphone battery rechargeable - Lithium Ion
Battery Capacity 55 mAh Worse than 71 % of in-ear headphones rated.
Battery Life 7 hour(s) Better than 58 % of in-ear headphones rated.
Battery Life Details Continuous playback (50% volume): up to 7 hours
Continuous playback (with included charging case): up to 20 hours
Charging Time 1.5 hour(s) Better than 88 % of in-ear headphones rated.
Included Qty 2

These headphones have a battery capacity of 55 mAh. In terms of headphone battery life as a significant factor in the purchase decision, it depends on what you want to use the headphones for and potentially how often you will be able to recharge them. Headphones with up to a few hours of battery life are more suitable for home use as they will require more frequent charging. Headphones with a battery life of around 10 hours or more are already more suitable for commuting and shorter journeys. However, nowadays you can also find headphones on the market that have a battery life in the higher tens to hundreds of hours. In this case, you do not have to worry about your headphones simply running out of power on longer journeys, and you will not have to deal with constant recharging. The battery life of the Sennheiser CX 400BT reaches up to 7 hour(s).

Charging time is 1.5 hour(s).

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OTHERS Sennheiser CX 400BT
Included Accessories 4 pairs of earpads (extra small, small, medium, large), charging case (420 mAh)
Compliant Standards Bluetooth Class 1, Directive 2006/66/EC, WEEE 2012/19/EU, Directive 2013/56/EU

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