ZK-502L 2x50W Mini Dual Channel Speaker Digital Power Amplifier Board Wireless Audio Stereo Bluetooth-compatible 5.0 Amp
Feature:
Bluetooth-compatible5.0 version, with higher transmission efficiency and longer transmission distance.
The potentiometer adjusts the volume, with a switch, it is convenient to control the volume, which is very suitable for DIY speakers.
Capacitor 470uf35V solid capacitor, to ensure the power storage and heat dissipation capacity, stable and continuous power supply is a prerequisite for good sound quality.
The copper DC connector is used, which can withstand high current and does not generate heat.
The DC head lead wire is compatible with the input power interface of this product. Even if you don't have a DC head adapter or battery, you can easily wire it.
Notice! The shell is a material package, you need to assemble it yourself, and a screwdriver is provided in the material package.

Specification:
Model: ZK-502L
Bluetooth-compatible version: 5.0
Material: Fiberglass board and electronic components
Adaptation power supply voltage: 5-24V (9/12/15/18/24V adapter is optional, high-voltage is recommended for high-power)
Adapter speaker: 30-200W, 4Ω, 8Ω
Number of channels: left and right stereo (stereo)
Bluetooth-compatible transmission distance: 15m (unobstructed)
Protection mechanism: self-recovery overheating protection, self-recovery short-circuit protection
Colour: Black
Weight: 50 grams
Dimensions: 55 x 38 x 17mm/2.17x 1.50 x 0.67in

Precautions:
The power switch on the board is a standby switch. After the switch is turned off, the machine is in a low-power standby state. To completely turn off the power or unplug the DC plug on the machine if it is not used for a long time.

Question answers:
1. How to choose the power source?
The board's power supply is crucial.The higher the voltage, the greater the current, the more power output, if you only have 12V 1A, this can carry 3-4 inch speakers.If you are above 19V 5A, with 8-10 inches no problem, power must be highly regarded.If the voltage is too low, the sound will easily cause distortion after amplification. If the current is too low to carry the speaker, the voltage will be pulled down, and the work will be abnormal or the sound quality will be poor.
It is recommended to use 18V19V24V power supply with current above 5A.If you only have 9V12V or 1A 2A power supply, you can also use it with low power. Be careful when using it at the maximum volume, it may cause distortion and affect the sound quality.
2. How to choose the speaker?
Common speakers are usually 8 ohms, can not distinguish between positive and negative polarity, the effect is the same, 4 ohms can also be used.If your horn power is small, it may be between 10W and 30W can also be used. The power supply voltage is small to prevent the speaker from burning down after playing loudly. For example, choose the power supply below 15V.If you are a 50W-300W speaker, don't worry about the speaker burning problem, you can choose a 12-24v power supply, the higher the selected voltage, then the greater the output sound or power.
3. How to connect Bluetooth-compatible?
Power up the power amplifier board, connect to the speaker, rotate the audio knob indicator light, turn on the phone Settings -- Bluetooth-compatible -- search to "bt-wuzhi", and then click connect, after connecting successfully, there will be ding dong prompt sound, at this time for Bluetooth-compatible mode, play music can, next time on the power will automatically connect.
4. It's okay if the voice is small, but when the voice becomes louder, the voice becomes muddy?
The sound is distorted, please change to a higher voltage adapter power supply.
5. It's okay if the voice is small, but when the voice becomes louder, the voice freezes?
The input power is insufficient, and the power supply itself is protected against intermittent power failure. Please replace it with a higher-power power supply; or if the power is too large, the power amplifier board generates serious heat and thermal protection occurs. Reduce power usage or enhance heat dissipation.

Note:
Due to the different monitor and light effect, the actual color of the item might be slightly different from the color showed on the pictures. Thank you!
Please allow 1-2cm measuring deviation due to manual measurement. 1 X Power Amplifier Board Set
1 X Material Package