MH-MX8 Wireless Bluetooth Audio Module 4.2 Stereo Lossless High Fidelity HIFI DIY Modification

Product Introduction:

This Product MH-M18/M28/M38 Is Designed as Bluetooth LE. It Supports the Latest Bluetooth 4.2 Transmission, Dual-Channel Stereo Lossless Playback, and Can Quickly Realize Bluetooth Wireless Transmission after the Module Is Connected to Bluetooth, very Convenient. In an Open Environment, the Bluetooth Connection Distance Can Reach 20 Meters.

Widely Used in Various Bluetooth Audio Reception, Various Audio DIY Modification, Etc.

 

According to the Different Needs of Customers, We Provide 3 One Versions for You to Choose from:

 

Function Description:

1. Bluetooth V4.2 version, supports Bluetooth automatic reconnection technology, supports WAV/WMA/FLAC/APE/MP3 lossless decoding, stereo two-channel output.
2. After the module is powered on, the phone searches for the Bluetooth name MH-M18/MH-M28/MH-M38, and after connecting to Bluetooth, music can be played
3. Module blue indicator light:

When Bluetooth is not connected, the indicator light flashes quickly;

When Bluetooth is connected, the indicator light stays on;

Bluetooth is connected to the device.

 

Below are introductions to each version:

MH-M18：

The module interface adopts a half-hole process; customers can directly mount or solder it onto the board.

 

 

No.PinDescription1KEYButton Control Terminal (4 Button Functions, Requires Additional Resistors)2MUTESilent control terminal (output high level 3.3V when silent, output low level when playing)3VCCPower supply positive pole 5V (lithium battery 3.7V power requires short circuit diode)4GNDPower Negative Pole5LLeft Channel Output6RRight Channel Output

 

MUTE mute control terminal: used to control the power amplifier board. When muted, MUTE outputs a high level of 3.3V; when playing, it outputs a low level.

Key Key-Press: This Function Can Only Be Realized by Connecting Resistor and Button. (The Corresponding Resistance Is Shown in the Wiring Diagram)

Volume power-off retention function: default output 100% volume.Through the button control volume increase decrease, if control volume less than 15%, then power on again after volume output is 15%; if control volume more than 15%, then power on again after volume output keep original volume unchanged.

MH-M28:

No.PinDescription15VPower supply positive pole 5V2GNDPower Negative Pole3VBATLithium Battery Positive Pole 3.7-4.2V4LLeft Channel Output5RRight Channel Output6AGNDAudio Ground

1. Power Supply: You Can Directly Use Micro USB Android Line 5V for Power Supply, Or Connect to 5V Power Supply Or 3.7V Lithium Battery (as Shown in the following Figure). Note That the Power Supply Interfaces of 5V and 3.7V Are Different. 5V Voltage Is Connected to 5V and GND, and 3.7V Lithium Battery Is Connected to VBat and GND.

2. Audio Output: the Headset Can Be Directly Connected to the 3.5mm Audio Interface Or Wired for Amplifier Board Audio Input (the Interface L/R/AGND Shown in the Figure Can Be Directly Wired).

MH-M38:

 

No.PinDescription15VPower supply positive pole 5V2GNDPower Negative Pole3VBATLithium battery cathode 3.7-4.2V4L+/L-Left channel output (directly connected to speaker)5R+/R-Right channel output (directly connected to speaker)

1. Power supply: You can directly use the MICRO USB Android cable for 5V power supply, or you can connect an additional 5V power source or a 3.7V lithium battery (as shown in the picture below).Please note that the power supply interfaces for 5V and 3.7V are different; 5V is connected to 5V and GND, while 3.7V lithium batteries are connected to VBAT and GND.

The maximum working current is 5V2A, it is recommended to use a 5V2A regulated power supply for better sound quality.

2.Support USB sound card, free driver (plug and play).Use a USB data cable to connect the module to the computer, and the computer can play music through this module for amplifier output

3. Audio output: Output left and right channel stereo audio signals, can be connected to two speakers of 2-8 ohms and 3-5W respectively, recommended for use   4 ohm 5W speaker.

 

4. This product already comes with dual 5W power amplifier circuits; do not connect additional amplifiers! The outputs of the two amplifiers cannot be connected in parallel or have their negative poles connected together, as this could damage the amplifier chip.

 

• Precautions

1. Signal interference: Bluetooth antennas are extremely susceptible to interference from high-frequency or strong electromagnetic signals; try to place them away from transmitting wireless devices.And the board should not be placed close to metal objects; maintain a certain distance

1. If there is an electric current sound when connecting to the power amplifier board, it is likely due to ground interference. It is recommended not to use plug-in wires for the Bluetooth module output but to solder wires instead, especially for the ground wire which should be soldered. The wire should not be too long; shorter is better and should be as thick as possible.The problem with the audio ground at the power amplifier board grounding point is that it needs to be connected to the power amplifier audio input terminal's ground. This grounding point can be tried by welding in different positions to achieve the lowest current noise.It is recommended to power the Bluetooth and amplifier board separately, isolating the Bluetooth ground from the amplifier ground.

1. Since this product is designed as a bare board, try not to touch the components on the board with your hands as it can easily cause static electricity to damage the chip and cause burning.

Warning: This product's charging interface operates in a current-limiting charging mode without charging management! For your safety and property security, please always use lithium batteries produced by regular manufacturers with protective boards. If any losses occur due to improper use, our company does not bear any responsibility!

Also: When using MH-M18, please pay attention to the following two points:

Power supply: Default is 5V power supply.If you need to use a 3.7V lithium battery for power supply, you need to replace the diode (as shown in the picture) with a 0603 0 ohm resistor or directly short-circuit both ends of the solder pad.

The Bluetooth audio module has very high power requirements which can affect audio quality. It is recommended to add an LC filter circuit, especially for switching power supplies (like phone chargers). 

MUTE Silent Port: This module outputs a high level of 3.3V when silent and outputs a low level of 0V during playback.If the power amplifier board's mute high level is effective, it can be directly connected.If the mute function of the power amplifier board is controlled by low level, you need to add a reverse circuit as shown in the following diagram: