JBL is a well-known audio brand under Harman Kardon. Its main products are speakers and headphones. With the popularity of TWS earphones, JBL has also launched a number of products to meet market demand. This time 52audio will be disassembled to be one of the main colorful color matching, lightweight and portable products – JBL FREE II true wireless earphones.
JBL FREE II is very compact in appearance design. The charging case adopts an oval cobblestone shape. The earphones are bean-shaped in-ear design, with ring indicator lights and JBL brand LOGO, which are very recognizable. In the configuration, it uses a high-quality 5.8mm high-sensitivity dynamic driver, bluetooth 5.0 chip, with JBL iconic sound effects; supports call noise reduction, IPX4 waterproof, and has a battery life of 6+18 hours.
| 1. JBL FREE II charging case teardown
We have already understood the overall design of the JBL FREE II true wireless bluetooth earphones through unpacking. Let’s enter the disassembly process and take a look at the internal structure and configuration of this product!
Open the cavity from the bottom shell of the charging case.
Charging case status indicator light guide.
The internal structure of the charging cavity.
The battery unit and the power input board are connected through a flat cable socket.
The battery and the main board are connected by wire welding, and the main board is fixed on the cavity by a plurality of screws.
Take out the internal circuit of the charging case, and the structure inside the charging cockpit is shown. The upper silver is an open cover structure, the middle two round magnets are used to adsorb the earphones, and the lower two square magnets are used to adsorb the charging case cover.
Charging case Open cover structure.
The back of the charging case internal circuit.
The front of the charging case internal circuit.
Type-C charging interface female socket in the middle of the power input board.
Pogo Pin on the small board for charging the earphones.
Rechargeable lithium-ion battery pack model: 862727, rated voltage 3.8V, rated capacity: 650mAh/2.47Wh, charging limit voltage: 4.35V, from Chongqing VDL Electronics Co., Ltd.
The silk-screen information on the battery cell is consistent with the label.
The battery is equipped with a circuit protection board, which is responsible for the protection functions of the battery such as overcharge, overdischarge, and overcurrent, and the chip pads are coated with glue.
charging case The front circuit of the motherboard.
charging case The circuit on the back of the motherboard.
Four LED indicators of different colors, the edge of the motherboard is edged by vias to prevent interference.
SMD transistor of silk screen Y1.
The voltage regulator tube of the silk screen 7TL.
The triode of silk screen HY4D.
The triode of the silk screen H1A.
The triode of the silk screen NF2T.
The regulator tube of the silk screen FCFY.
The IC of the silk screen QBT.
Silergy SY6918C battery charge and discharge management IC, supports 18V withstand voltage, supports 2A charging, 2.5A boost output, supports 4.2/4.35V battery, supports programmable current display, dynamic power management, and is responsible for charging case internal battery charging and boosting The output is charging the earphones.
APTCHIP APT32F101H6SV microcontroller. APT32F101 is a low-cost, high-performance series of single-chip microcomputers, using the 32-bit single-chip core developed by C-Sky, mainly used in home appliances and portable devices.
| 2. JBL FREE II earbuds teardown
The JBL FREE II earphones have a bean-shaped in-ear design and a matte body.
The back of the earphone is curved, with a ring indicator light and JBL brand LOGO, which is highly recognizable.
The earphone microphone has an opening, and the internal dust-proof net covers.
Metal contacts for charging.
The front and back chambers of the earphone are fixed with glue.
Open the cavity along the parting line.
The internal front cavity and the back cavity components are connected by a flat cable and a BTB connector.
The front and rear chambers of the earphone can be separated by opening the BTB connector. The battery and speakers in the front chamber are connected to the earphone main board through the connector.
The BTB on the motherboard uses OCN (Yaqi Technology) high-current connectors, model: OK-35F006-04, with a pitch of 0.4mm, a height of 0.6mm, and a current of 3A.
According to 52audio, wireless earphones from brands such as Huawei, Xiaomi, OPPO, JBL, Baidu, OnePlus, and Amazon have adopted OCN connectors.
Inside the back cavity is the main board unit, and the left and right earphone circuits are slightly different.
There is a circular insulating sheet between the battery and the earphone circuit board.
Soft pack battery type 1254, rated voltage 3.7V, rated capacity 0.2Wh.
The small board for charging the earphones, the circular magnet is attached to the charging cockpit.
The speaker uses a dynamic driver and is fixed on the inner side of the sound tube.
After actual measurement, the size of the speaker unit is about 5.8mm.
Remove the motherboard and the internal structure of the earphone’s back cavity. The ring indicator light guide is fixed by a buckle, and the edge is a metalized bluetooth antenna.
Remove the ring indicator light.
The circuit on the front of the motherboard.
A list of the circuits on the back of the main board. The microphone is sealed with a separate rubber cover to improve the radio effect.
Microphone sealing rubber cover.
The Pogo Pin connected to the LDS bluetooth antenna on the motherboard.
Two LED indicators of different colors.
The micro buttons on the main board support single-click, double-click and long-press, which are used to control various functions.
There are also two LED indicators under the tilt light barrier.
MEMS silicon microphone, used for voice call pickup.
The charging IC of the silk screen 51D charges the built-in battery of the earphones.
XySemi XB6096IS integrated battery protection IC for the protection of the built-in battery of the earphones.
The bluetooth filter of silk screen 129.
BES BES2300IZ bluetooth audio SOC, BES2300 has multiple versions, different configurations with different suffixes, and 52audio has classified this in detail before.
The BES2300 series is a fully integrated adaptive active noise reduction solution that supports bluetooth 5.0, IBRT low-frequency forwarding technology and dual-mode bluetooth 4.2. It also supports the third generation of FWS full wireless stereo technology, dual microphones, etc., using 28nm HKMG CMOS process, BGA package . BES2300 supports high-performance adaptive active noise reduction technology, which allows high-end active noise reduction headphones to use a fully integrated chip to achieve high sound quality and active noise reduction.
In addition, BES2300 also supports external heart rate sensors, acceleration sensors and other external sensor devices and eMMC flash memory, which can achieve the purpose of playing music on external storage devices. BES2300 can output sound to headphones and home audio, and can also record from an external microphone.
According to 52audio, a large number of true wireless earphones from brands such as Huawei, Samsung, Xiaomi, OPPO, JBL, 1MORE, Honor, Baidu, and OnePlus have adopted BES solutions.
All components of JBL FREE II true wireless bluetooth earphones.
| 3. Summary
As JBL’s first true wireless earphones, JBL FREE, the first upgrade product after a lapse of 3 years, JBL FREE II has both a continuation and a new change in design compared to the previous generation product. The charging case is more compact, the earphones continues the overall shape of the previous generation, but the texture is richer. The ring indicator light matches the JBL brand LOGO, which is very recognizable.
In terms of internal circuits, two PCBA boards are used inside the charging case, which are connected through a flat cable and a socket. The charging case uses the Type-C charging interface to input power, the lithium-ion soft pack battery has a capacity of 650mAh, and is equipped with a circuit protection board that is responsible for battery overcharge, overdischarge and overcurrent protection functions; the battery and the motherboard are welded by wires, and the motherboard is equipped with SILERGY SY6918C battery charge and discharge management IC, responsible for charging case internal battery charging and boost output for earphone charging; an APTCHIP APT32F101H6SV microcontroller, used for whole machine control.
In the JBL FREE II earphone part, the moving coil speaker, battery and charging plate in the front cavity are welded on the same FPC cable, and then connected to the main board unit in the back cavity through the BTB connector; the main board is connected to the LDS bluetooth antenna on the cavity through the Pogo Pin , The main control chip is BES BES2300IZ, supports bluetooth 5.0, is used for earphones bluetooth connection and bluetooth signal processing; XySemi XB6096IS integrated battery protection IC is used for earphones built-in battery protection; a MEMS silicon microphone is used for voice calls.