Today, 52audio is teardown the Panasonic Technics EAH-A800 over-ear bluetooth headphones. This headphone supports LHDC transmission technology and has a 3.5mm audio interface. The headphone has a built-in 40mm driver unit, providing users with a more immersive and shocking listening experience. In terms of noise cancelling, the headphone has built-in 8 microphones to achieve high-definition calls and strong noise cancelling experience.
Technics EAH-A800 headphones teardown
Remove the headphone cover.
Inside the headphone earmuffs, the sound area is covered with a fine dust-proof mesh.
The internal structure of the back shell of the left headphone.
There is a fine layer of sponge at the bottom of the headphone cover for cushioning and sealing.
Remove the headphone foam pad.
The air pressure balance hole of the unit is covered with white toning cotton.
Speaker unit with protective frame on the outside.
After actual measurement, the diameter of the drive unit of Technics EAH-A800 over-ear bluetooth headphones is about 40mm.
The feedback microphone has a fixed position with an acoustic cover, and the cover is fixed in position with screws.
Unscrew the acoustic cover screws and remove the cover, the back of the cover.
The position of the acoustic cover corresponding to the microphone is provided with a fine dust-proof net to prevent foreign objects from entering.
The microphone under the acoustic cover is fastened to the protective bracket above the driver unit.
Use tweezers to remove the noise cancelling microphone.
Laser engraved “173A03 1q” MEMS microphone.
Unscrew the screws of the headphone cavity cover and remove the headphone cover.
The battery of the headphone is installed on the back of the headphone cover.
The back of the headphone cover. A battery is provided, and the cover circuit is connected to the mainboard of the headphone through wires and FPC cables.
Use tape to fix the FPC cable of the headphone cover.
The tuning holes on the headphone cover are used to balance the internal and external air pressure and improve the acoustic performance of the headphone.
The headphone lithium-ion battery is from VDL. Model: 763041, rated capacity: 1000mAh/3.7Wh, nominal voltage: 3.7VDC, charging limit voltage: 4.2V.
Remove the insulating tape and label on the outer layer of the battery, and the screen printing information on the battery outer skin is consistent with the label information.
The battery is equipped with a circuit protection board with a battery fuse.
On the back of the battery protection board, there are ICs and MOS tubes for protection circuits.
The internal structure of the headphone cavity.
The headphone feed-forward microphone, the small board silk screen information “MIC-FF-L”, the microphone small board is fixed in the specially set slot position.
Headphone feed-forward microphone, laser engraving information “102ARC”.
Headphone’s call microphone, small board silk screen information “MIC-TK-L1”.
Headphone call secondary microphone small board.
The MEMS microphone of the laser engraving “S26334965” is the secondary microphone of the headphone, which is used to work with the main microphone of the call to bring the voice directional beamforming to a high-definition call experience.
The front of the left headphone arc-shaped motherboard is provided with multiple interface sockets.
On the back of the arc motherboard of the left headphone, a lot of wires are soldered on the back.
TI BQ24075 1.5A single-cell lithium battery linear charger, the input supports 28V withstand voltage, used for charging the built-in battery of the headphone. It adopts QFN package, has battery temperature detection function, and supports path management.
Silkscreen “T” resettable fuse for overcurrent protection.
The resettable fuse is close.
TI TPS63802 High Efficiency, High Output Current Buck/Boost Converter. Depending on the input voltage, it automatically operates in boost, buck, or the new 4-cycle buck/boost mode when the input voltage is approximately equal to the output voltage. Mode switching is performed within a defined threshold to avoid unnecessary intra-mode switching to reduce output voltage ripple. The output voltage of these devices is individually adjustable over a wide output voltage range with resistive dividers. Quiescent current of 11µA enables excellent efficiency at ultra-low and even no-load conditions.
The TPS63802 is a high efficiency, high output current buck/boost converter. Depending on the input voltage, it automatically operates in boost, buck, or the new 4-cycle buck/boost mode when the input voltage is approximately equal to the output voltage. Mode switching is performed within a defined threshold to avoid unnecessary intra-mode switching to reduce output voltage ripple. The output voltage of these devices is individually adjustable over a wide output voltage range with resistive dividers. Quiescent current of 11µA enables excellent efficiency at ultra-low and even no-load conditions.
Next, enter the right headphone teardown session. Compared with the left headphone, the right headphone integrates all the control buttons of the headphone.
The structure of the right headphone cavity cover is the same as that of the left headphone cavity cover.
The right headphone speaker unit has an in-ear detection ring-shaped induction patch attached to the surface of the protective frame. In order to enhance the detection sensitivity, the inner side of the earmuff is basically fully covered.
Remove the cavity cover.
The back of the cavity cover.
The internal circuit of the right headphone is connected by wires and the circuit of the FPC cable and the cavity cover.
The internal structure of the right headphone cavity.
The light guide column on the curved motherboard.
The light guide column is removed, and the light guide column is provided with a positioning column for assembling with the arc mainboard.
Unscrew the arc motherboard screws and remove the arc motherboard.
The FPC circuit in the front shell of the headphone is positioned using the post hole, and the center is the touch area.
There are independent brackets on the inside of the four function buttons of the headphone to support the button motherboard.
The back of the motherboard circuit of the right headphone.
The front of the motherboard circuit of the right headphone.
The 3.5mm audio interface on the motherboard can be converted into a wired HiFi headphone by using the audio interface to plug in the audio cable.
The LED lights on the motherboard are used to indicate the working status of the headphone.
Micro buttons on the motherboard.
Silkscreen “T” resettable fuse for overcurrent protection.
TI TPS259531 5.7V overvoltage protection chip for input overvoltage protection. It supports 4A current, and the built-in switch tube resistance is 34mΩ.
Bluetooth antenna board.
Two ICs with silkscreen “ENAB B5H”.
Silkscreen “M4AA B30” IC.
TI TS3USB331E USB signal multiplexer and splitter for USB signal switching between different devices.
TI BTCA9535TCA9535 low voltage 16-bit C and SMBUS. Available through interrupt output and configuration register 1 Function 3 Description PC to Parallel Port Expander TCA9535 is a 24-pin device that provides 16-bit switching power supply voltage range 1.65V to common CBU) Protocol device can operate with low standby current consumption Supply voltage range 1.65V To 5.5V Active Low Interrupt Output 5-V Fault Tolerant UO Port 400 KHZ Fast PC Bus Polarity Inversion Register (Operation) Register.
At power-up, the OSA address is used as input or output by three hardware address pins by writing to the MO configuration bits of up to eight devices. The TCA9535 is equally capable of driving LEDs directly, and the TCA95 latching performance exceeds 100 mA per pull-up resistor, which requires a full JESD 78.
Silkscreen “SV4CP 2JF” IC.
Silkscreen “C1AG” IC.
Silkscreen “D10LB” DSP chip.
Airoha AB1565 single-chip Bluetooth 5.2 dual-mode SoC. Built-in ARM M4 processor core, the highest running frequency is 208MHz, the built-in DSP running frequency can reach 416MHz, with USB, I2C, UART, SPI, PWM, AUXADC, I2S multiple interfaces, can be connected to a variety of peripherals.
The AB1565 has a built-in highly integrated power management unit with integrated switching buck and voltage regulator circuits. Built-in lithium battery charger with over-current and over-temperature protection. AB1565M and AB1565AM have built-in 8MB flash memory. The chip supports 24/192 audio, supports hardware active noise cancelling, supports feedforward noise cancelling and hybrid noise cancelling. Supports noise suppression and echo cancellation, built-in multi-band programmable EQ and dynamic range control.
Airoha AB1565AM supports Google/AMA/Siri and other voice assistants, provides software development tools, and provides reference for smartphone APP development. AB1565AM adopts 5.6*4.6mm TFBGA package. In addition to being used in TWS earbuds, Airoha AB1565 can also be used in applications such as stereo headphones, bluetooth speakers, bluetooth speakers, and bluetooth transmitters, providing high-quality bluetooth audio for these applications.
According to 52audio, a large number of bluetooth headphones on the market including Sony, Redmi, Beats, TOZO, OPPO, ZMI, RHA, Zepp Health Corporation, 1MORE, realme, FIIL, Edifier, Plantronics, Earsopen and other brands have adopted Airoha’s solutions.
Built-in DSP chip, model C2A1C, used for digital signal filtering of the headphone.
Panasonic Technics EAH-A800 ANC over-ear bluetooth headphones all components.
In terms of appearance of Technics EAH-A800 over-ear bluetooth headphones, the earmuffs are designed with a vinyl pattern, revealing an elegant atmosphere in a low-key manner.
In terms of functions, the headphone has 4 built-in microphones on one side, 2 for noise cancelling, and 2 for voice call pickup, bringing users ultra-high-definition calls and ultra-quiet noise cancelling experience. In order to take into account the needs of high-quality players, the headphone has a built-in DSP chip and a 3.5mm interface, and the headphone can be converted into a wired HiFi headphone by plugging in the audio cable to meet the needs of different users.
In terms of internal configuration, the bluetooth chip of the headphone is Airoha AB1565 single-chip Bluetooth 5.2 dual-mode SoC. Built-in ARM M4 processor core, the highest running frequency is 208MHz, the built-in DSP running frequency can reach 416MHz, with USB, I2C, UART, SPI, PWM, AUXADC, I2S multiple interfaces, can be connected to a variety of peripherals. The chip supports 24/192 audio, supports hardware active noise cancelling, supports feedforward noise cancelling and hybrid noise cancelling. Supports noise suppression and echo cancellation, built-in multi-band programmable EQ and dynamic range control.
In terms of circuit, the headphone uses TI TPS63802 high-efficiency, high-output current buck/boost converter to achieve ultra-high-speed fast charging with 15 minutes of charging and 10 hours of battery life. The battery of the headphone comes from VDL, model 763041, rated capacity: 1000mAh/3.7Wh, and can achieve a single battery life of up to 60 hours.