Sennheiser CX Plus still continues the Sennheiser family-style design style in appearance, and has a high brand recognition. In terms of functional configuration, it is equipped with a 7mm TrueResponse drive unit independently designed and developed by Sennheiser, and the lowest frequency response can be lowered to 5Hz. Support aptX and aptX adaptive audio codec.
In other respects, it supports ANC mode/transparency mode, providing an immersive music experience, and at the same time ensuring that the external ambient sound can still be easily perceived when wearing headphones. The dual-microphone beamforming array test mode is adopted to provide a clearer call effect. It supports IPX4 waterproof and has a comprehensive battery life of 8+16 hours. Let’s take a look at the teardown report of this product in detail.
$129 – Sennheiser CX Plus Review
01/ Sennheiser CX Plus charging case teardown
Now enter the teardown section to see the internal structure configuration information.
Pry off the shell of the charging case, the bottom of the charging case is fixed with a battery, which is connected to the main board on the back of the cockpit through wires.
The bottom of the cockpit is fixed to the main board with screws, and the battery wires are welded on the main board and glued to fix it.
A sponge pad is provided for protection between the battery and the main board in the cavity.
The main component of charging case is teardown. The circuit is relatively simplified, including only the battery and the motherboard.
There is parameter information silkscreened on the battery label, model: AHB651935PST-01, rated capacity: 420mAh 3.7V, charging limit voltage: 4.2V, from SYNERGY.
The silkscreen information on the battery is consistent with the external label.
The battery circuit protection board is equipped with lithium battery protection and 8205 MOS tube with silk screen printing as RZYV, and a thermistor for detecting battery temperature.
Circuit on the motherboard side.
Circuit on the other side of the motherboard.
The Pogo pin connector on the motherboard for the earbud charging communication. The long Pogo pin is for earbud charging and the short Pogo pin is for communicating with the earbud.
Buck inductor for battery charging.
MPS MP2615 screen printing AEG is a lithium battery charging chip that supports 2A charging current. The internal integrated switch tube supports charging support, has a programmable safety timer, supports thermal shutdown protection and cycle-by-cycle overcurrent protection functions.
Boost IC for SC8LF.
Type-C charging interface female socket.
ST STM32G031G6 mainstream Arm Cortex-M0+MCU, with 32KB flash memory, 8KB RAM, 64MHz CPU, 2xUSART, timer, ADC, communication, interface, working voltage 1.7-3.6V. Used for charging case control and communication control.
Silkscreen 4ALA IC for input overvoltage and overcurrent protection.
02/ Sennheiser CX Plus earbuds teardown
Proceed to the earbud teardown section. Pry open the cavity along the parting line.
The battery inside the rear cavity is taken out, and a frame is arranged in the rear cavity for fixing the main circuit.
Take out the inner frame of the rear cavity and the inner structure of the outer shell.
Touch detection electrodes are printed on the shell, and a red pickup microphone sealing rubber cover is provided to improve the sound pickup performance. The upper left corner is the contact point of the bluetooth antenna.
Pry off the back decorative piece, and the bluetooth antenna is printed on the inside.
Remove the motherboard and cables from the frame.
An FPC board is arranged inside the front cavity, which is fixed by a hot-melt column.
Pry open the FPC board in the front cavity, the internal structure of the cavity, the end of the cable is welded with the speaker in the sound tube.
Melt the solder joints that connect the cable to the speaker and pry open the sound chamber.
Take out the TrueResponse drive unit inside the cavity.
The front diaphragm of the TrueResponse driver unit, the voice coil exits on both sides, and is fixed on the diaphragm with glue.
On the back of the TrueResponse driver unit, a tuning hole is designed to improve acoustic performance, and it is protected by a dust filter.
After actual measurement, the size of the speaker is about 8mm, and the outside of the diaphragm is protected by a frame.
Internal structure of earbud anterior cavity.
The optical sensor opens the inner structure of the window.
Sennheiser CX Plus earbuds main component teardown.
The call pickup microphone on the cable is sealed by a red rubber cover.
Laser engraving AT21 5E32 MEMS microphone for voice pickup.
The end of the cable connects to the contacts of the motherboard’s ZIF connector.
The circuit on the FPC board.
LED indicator for feedback earbud bluetooth pairing status and remaining battery information.
Infrared distance sensor is used for in-ear detection function, which can automatically pause music playback when it is removed, and automatically resume playback when it is worn.
Four metal copper pillars for charging/communicating earbud.
Silkscreen C152 lithium battery protection IC.
One side of the steel shell button battery inside the earbud, model: LIR ZJ1254C21C, rated voltage: 3.7V, capacity: 55mAh/0.204Wh.
The battery negative engraving information has a charging limit voltage: 4.2V, from VDL.
The circuit on one side of the earbud motherboard.
The circuit on the other side of the motherboard.
Qualcomm QCC3056 bluetooth audio SoC is an ultra-low power, single-chip solution. It adopts WLCSP package, built-in powerful quad-core processor architecture, supports Bluetooth 5.2 and Qualcomm TrueWireless mirroring technology. Provide stable connection, support aptX Adaptive audio decoding, adaptive active noise cancellation, cVc echo cancellation and noise suppression, etc., and support Qualcomm Snapdragon Sound audio technology platform.
According to 52audio, there are many TWS earbuds, over-ear headphones, neck hanging bluetooth earphones, smart speakers, smart audio glasses and other audio products that use Qualcomm bluetooth audio SoC.
The 32.000MHz crystal oscillator provides the clock for the bluetooth chip.
Silkscreen X2E IC.
Silkscreen 9BFL87 IC.
MOSFET from TI CSD85302L. This 20V, 18.7mΩ, dual NexFET power metal-oxide-semiconductor field-effect transistor (MOSFET) in a 1.35mm × 1.35mm land grid array (LGA) package is designed to minimize resistance in the smallest form factor.
Silkscreen EJ’s IC.
Laser engraving AT21 6G21 MEMS microphone is used for noise cancellation function to pick up external environmental noise.
Metal dome for connecting the bluetooth antenna.
Metal dome used to connect touch detection electrodes.
ZIF connectors for connecting cables.
Silkscreen 77CLW memory IC.
Screen printing SA2N5 touch detection IC.
Silkscreen J9O IC.
All components of SENNHEISER CX Plus true wireless earbuds.
The Sennheiser CX Plus charging case adopts a white color that is biased towards light gray in terms of appearance, and is treated with a matte finish. The earbuds have a bean-shaped in-ear design, and the back panel is decorated with a transparent sheet to enhance the texture of the product. Ergonomically designed in-ear curve with 4 sizes of silicone eartips for a comfortable fit.
In terms of internal structure and configuration, the internal circuit of the charging case is simple, the built-in battery capacity is 420mAh, and it is equipped with a circuit protection board from SYNERGY. On the main board, it is equipped with MPS MP2615 lithium battery charging chip, integrated switch tube, with programmable safety timer, and supports thermal shutdown protection and cycle-by-cycle overcurrent protection functions. ST STM32G031G6 microcontroller with 32KB flash, 8KB RAM, 64 MHz CPU, 2xUSART, timer, ADC, communication, interface.
The earbuds part is equipped with a 7mm TrueResponse drive unit independently developed by Sennheiser. Two MEMS microphones are used for active noise cancellation and voice call functions. The earbud has a built-in VDL 55mAh high-capacity steel shell button battery, and a lithium battery protection IC is set on the FPC board. On the motherboard, the main control chip is Qualcomm QCC3056 bluetooth audio SoC, which supports Bluetooth 5.2, aptX Adaptive audio decoding, adaptive ANC, cVc echo cancellation and noise suppression.