TWS true wireless earphones have entered a new stage of functional upgrades this year. The active noise reduction function has become popular, and the overall noise reduction effect has improved significantly compared with before. More and more brands have begun to deepen the adaptive noise reduction and earphone sound quality. the study. In this regard, Sony launched TWS noise-cancelling headphones earlier, which has mastered the LDAC audio codec technology, has also started to act. After two years, it finally launched a new generation of flagship true wireless noise cancelling earbuds – Sony WF-1000XM4.

Sony WF-1000XM4 has obvious changes in appearance design, with prominent curved and circular design elements, rounded earphones, compact charging case, and significant upgrades in active noise reduction and sound quality. WF-1000XM4 uses the new V1 noise reduction chip, supports AI intelligent noise reduction, can automatically adjust the noise reduction depth and the size of the music sound according to environmental changes, and can switch different environmental sound and noise reduction schemes according to the location; Sony also equips the headset New slow rebound eartips have been added to improve the passive noise reduction effect.

In terms of sound quality, Sony WF-1000XM4 is equipped with a new 6mm speaker driver unit. The main control chip supports LDAC audio encoding. It can transmit and stream high-resolution audio with a sampling rate of 24bit/96KHz via bluetooth. The transmission speed can reach up to 990kbps. Play lossless audio on streaming platforms. WF-1000XM4 also supports Sony’s DSEE Extreme digital sound enhancement engine, which can optimize audio quality in real time and enhance the sense of hearing. These two technical blessings have also enabled Sony WF-1000XM4 to obtain the Hi-Res Wireless gold standard sound quality certification. In addition, the headset also supports Sony’s 360 presence sound effects.

The Sony products teardown by 52audio include: Sony WF-XB700, Sony WF-H800, Sony WF-SP900, Sony XPERIA Ear Duo open true wireless earphones and earlier TWS headsets.

$229 - Sony WF-1000XM4 Review

| 1. Sony WF-1000XM4 charging case teardown

After opening the box, we have already got a comprehensive impression of the appearance of the Sony WF-1000XM4. The charging case is small and the headset has a distinctive design. Next, we will enter the disassembly process to take a look at the internal structure and materials.

Pry open the charging cockpit shell along the side, there are many physical buckles.

The internal structure of the charging case is shown on the front, with a multi-layer “hamburger” structure. The black tape is to avoid light leakage from the housing.

At the bottom is the wireless charging receiver coil.

The internal structure is shown on the back.

The battery is connected to the main board through a connector, which is convenient for assembly and later replacement.

The shell material of the earphone is connected by a buckle, which is convenient for assembly and production.

The structure at the shaft is fixed with screws.

Wireless charging receiving coil.

The light guide plate at the position of the indicator light.

Disconnect the connector and the buckle, and separate the internal structure of the charging case.

There is a plastic protective cover between the outside of the battery and the main board, and there is cushioning foam at the inner contact position.

The motherboard is fixed with multiple screws.

The internal structure of the charging cockpit after the motherboard is removed, there are two magnets in the earphone position to fix the earphones, and a magnet to absorb the box cover at the opening of the box cover.

The circuit on the motherboard side is shown, the upper half is the power management circuit, and the lower half is the wireless charging receiving circuit.

The circuit on the other side of the motherboard shows a larger SoC chip.

The USB Type-C interface is soldered to the motherboard via vias.

There are self-recovery fuses at the input, TVS and overvoltage protection chip for input protection.

Screen printing 2047 323 input protection chip.

TI BQ25618 charging IC integrates charging, boost converter and voltage protection functions, supports 22V withstand voltage, and is used to charge the built-in lithium-ion battery of the headset.

TI BQ25618 detailed information.

Judging by the pin definition and packaging form, the boost chip is a TI TPS6124x series product, with a synchronous rectification boost, and a built-in switch tube to boost the battery to charge the headset.

TI TPS6124x details.

Mitsumi silk-screened A33 regulator tube.

Responsible for the resonant capacitor and filter capacitor for wireless charging and receiving.

Renesas IDT P9222-R low-power wireless power supply 5W receiver solution. The device receives the AC power signal sent from the wireless power transmitter and converts it into a rectified output voltage, which can be used to power devices for various wireless power applications or to supply battery charger inputs.

The Renesas IDT P9222-R receiver (Rx) integrates a high-efficiency synchronous full-bridge rectifier (SFBR) and a control circuit used to send information packets to the transmitter (Tx) to achieve the best power transmission. The device includes over-temperature and under-voltage/over-voltage protection. The internal over-voltage clamp protects the rectified output from being higher than the over-voltage setting level, especially when the receiver quickly changes from a low-coupling position to a high-coupling position. The device also integrates a 32-bit ARM® Cortex®-M0 processor, providing a high level of programmability and design parameters, and it can be configured through an I2C interface or an external EEPROM.

Renesas IDT P9222-R details.

The charging case battery comes from Springpower Technology, the charging limit voltage is 4.4V, the nominal voltage is 3.85V, and the rated capacity is 520mAh/2.0Wh.

The information on the battery cell is consistent with the label, and the battery model is SP702428.

The battery protection board is responsible for the overcharge, overdischarge and overcurrent protection of the battery, with a thermistor to detect the battery temperature.

NXP K32 L2B series microcontroller, built-in ARM-M0 core, is a customized model for Sony; it is used to realize charging case control functions such as charge and discharge module management, battery power management, indicator light control, and headset communication.

Silk screen XBD IC.

Silkscreen 75 RR IC.

The Hall element of silk screen 20401 senses the magnetic field change (Hall effect) when the charging case cover is opened/closed, and then informs the charging case control chip, and then informs the headset to connect/disconnect with the paired device, realizing the function of opening and closing the cover.

Indicator light.

Two of the gold-plated Pogo Pins are responsible for charging the battery, and one is responsible for controlling the status.

| 2. Sony WF-1000XM4 earbuds teardown

Let’s continue to disassemble the earphone and pry open the shell along the mold line.

The two parts inside and outside of the earphone are connected by a BTB connector.

The internal structure of the headset is displayed, and there is a sealing rubber ring at the seam. On the right is the circuit inside the earphone housing, and on the left is the circuit inside the earphone cavity.

Let’s take a look at the relevant circuit of the shell part.

The internal components of the earphone are basically fixed with this kind of glue, and can be removed after heating and softening.

The shell is a multi-layer structure combined together. The left side is the feed-forward microphone pickup hole, and the right side is the call microphone pickup hole. Both holes are covered with waterproof membrane.

The sound pickup hole of the call microphone has a cavity inside, and the top is a strip-shaped opening seen from the outside. The opening of the feedforward microphone is also a special structural design, and the outside is in the shape of an interface. For the sake of combating wind noise, these two microphones have a unique design of pickup holes.

The LDS antenna for wireless signal transmission and the PAD for touch sensing are integrated in the outermost shell, and the main board is connected through contacts and metal dome.

Laser carving K56A K091 MEMS silicon microphone.

The circuit display on the side of the motherboard is the Bluetooth master chip and its peripheral circuits.

Metal dome connecting the Bluetooth antenna and the touch pad.

Circuit display on the other side of the motherboard.

The Sony WF-1000XM4 main control chip uses the MediaTek/Airoha MT2822 platform solution. This chip supports the latest Bluetooth 5.2 version, is equipped with Airoha MCSync TWS dual-transmit Bluetooth transmission mechanism, supports wireless high-resolution sound quality LDAC encoding, and helps WF-1000XM4 get Hi- Res Wireless sound quality certification.

Sony’s leading noise reduction technology combined with the function of the active noise reduction filter integrated on the MT2822 platform can provide consumers with an excellent listening experience and enjoyment. It has the characteristics of fast computing speed, good noise reduction performance, and low power consumption.

External Q128J memory is used to store firmware information.

The IC of the silk screen C1BB.

Silkscreen 761PK4U1 integrated battery protection IC.

Silkscreen XF 05 IC.

Part of the motherboard circuit display.

Continue to look at the internal structure and materials of the earphone cavity. The feed-back microphone is connected to the external main board through an FPC.

The upper part is a BTB connector that connects to another motherboard, and the lower part is an FPC connector. The connection forms of the two are different, but both are convenient for production and assembly.

The metal dome connecting the negative electrode of the battery.

Layers of layers are stacked inside the cavity.

Remove the button battery.

The red plastic bracket for fixing the battery.

The button battery comes from ZeniPower, model Z55H, with a rated voltage of 3.85V and an energy of 0.29Wh.

52audio learned that Sony  WF-H800 TWS true wireless Bluetooth headset, Philips SHB4385 TWS true wireless Bluetooth headset and other products have adopted ZeniPower button batteries.

Use a soldering iron to remove the charging copper pole to take out the PCB inside the headset.

PCB display in the front cavity.

Display on the other side of the PCB. The contact position with the battery is covered with insulating tape.

Display on one side of the small board. On the right is the metal dome connected to the positive electrode of the battery.

Display on the other side of the small board. The left side is the solder joint of the charging copper pillar, and the right side is the metal dome connecting the speaker unit.

The bone conduction sensor can accurately collect the vibration information of the human vocal cord, and is used for functions such as call noise reduction and intelligent pick-free.

The infrared optical distance sensor is divided into two parts: transmitting and receiving.

The metal dome connecting the positive and negative poles of the speaker unit.

The IC of silkscreen 84.

The internal structure of the front cavity is displayed.

The filter protection lens of the infrared optical distance sensor.

The circular magnet that attracts the charging case.

The positive and negative contacts of the speaker unit.

The signal line made by LDS technology is used to connect the speaker unit.

Laser carving K56A K109 MEMS silicon microphone.

The new 6mm speaker driver unit promoted by Sony uses a highly flexible diaphragm, and the volume of the magnet is increased by 20% compared with the previous generation. It has better sound performance in high, middle and low frequencies. For waterproofing, the unit is enclosed in a semi-hermetic mold.

The maximum diameter outside the measured speaker unit is about 7.3mm (including the metal casing).

The fixed position of the loudspeaker unit and the structural design of the mouthpiece. The contour fixed with black glue fits the unit mold for waterproofing.

All components of Sony WF-1000XM4 true wireless noise canceling earbuds.

|3. Summary

Sony’s new generation of “noise reduction beans” WF-1000XM4 true wireless noise reduction headphones, the first impression is that they are small, but this smallness is relative to the previous generation products, the charging case has been reduced by 40% in volume, and it is curved. The shape of the earphone is easier to put in your pocket; the appearance of the earphone incorporates a large number of circular design elements, and the volume is not small compared with other bean-type in-ear products on the market. It will touch the top of the auricle when worn, so it is worn by different groups of people There will be a certain difference in feeling.

In terms of internal circuits, the charging case inputs power through the USB Type-C interface, with TVS and overvoltage protection chips for input protection; TI BQ25618 integrates charging, boost converter and voltage protection functions to charge the battery; Renesas IDT P9222-R Responsible for wireless charging reception and supporting Qi standard; soft pack battery comes from Springpower Technology with a rated capacity of 520mAh; TI TPS6124x is responsible for boosting battery output to charge the headset; NXP K32 L2B series microcontroller is responsible for the overall control of the charging case.

In the earphone part, Sony WF-1000XM4 uses slow rebound eartips to reduce the penetration of high-frequency noise. The feedforward microphone is a rare design at the bottom of the earphone. It has a special anti-wind noise design. The earphone adopts a hybrid noise reduction scheme. The noise reduction function is reduced by Sony. The noise algorithm is implemented with the active noise reduction filter integrated on the MediaTek MT2822 platform. The chip supports Bluetooth 5.2, supports LDAC high-resolution audio encoding, and has the characteristics of stable connection, fast calculation speed, good noise reduction performance, and low power consumption.

Sony WF-1000XM4 newly adopts bone conduction sensor to collect human vocal cord vibration information, which is used to realize functions such as call noise reduction and smart hands-free; not only Bluetooth antenna and touch pad are manufactured through LDS process, but the signal line of the speaker unit is also adopted. This process has better performance and is convenient for factory production and assembly; the button battery used in the headset comes from ZeniPower, with an energy of 0.29Wh and about 75mAh.

Sony WF-1000XM4 does not have a complicated internal structure, but optimizes and improves many aspects such as function realization, circuit design, space utilization, and improvement of production efficiency. It is simple but not simple, and it has also set a Sony true wireless headset in product pricing. The new height of the product is intended to consolidate its competitiveness in the high-end TWS headset market.

Source: 52audio

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  1. Hello,

    Is it possible to charge earplugs by using only two, plus and minus pins?

    What signal pin does, and can I skip it?

    I lost my case, and if like to charge via usb.


    • Although it is charged through the plus and minus pins, the charging scheme of each brand is different. I’m also not sure if it is feasible.

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