1pc ZK-TB21 2.1 Channel Subwoofer Power Amplifier Board with 50W+50W+100W HIFI control, BT/AUX input, DC powered (max 36V) for DIY speakers. No battery included.

This is a 1pc ZK-TB21 2.1 Channel Subwoofer Power Amplifier Board with 50W+50W+100W HIFI High & Low Frequency Control. It is a Stereo Digital Audio Amplifier Module with BT/AUX Input, suitable for DIY Wireless Speakers. The amplifier is DC powered, with a maximum input of 36V, but does not include a battery.

The package contains: ZK-TB21 Power Amplifier Board * 1, Protective Shell * 1 Set, Power Adapter * 1, Screwdriver * 1, Knob * 5. Please note that the power supply is not included, so you will need to use your own.This module is a 2.1 channel Bluetooth audio amplifier with model ZK-TB21. It supports Bluetooth version 5.0 with a range of 10 meters. The input sensitivity is 500mV, and it can be connected via AUX or Bluetooth. It has two main channels and one subwoofer channel. The power supply should be DC 12-24V/5A or higher for optimal performance. The amplifier is suitable for speakers ranging from 20-100W with impedance of 4-8 ohms. The output power is limited to 50W for the main channels and 100W for the subwoofer. It includes protection mechanisms for overvoltage, undervoltage, overheating, and short circuits.Make sure the adapter power supply has more power than the actual working power of the amplifier to ensure sufficient output power. The higher the power supply voltage and the smaller the horn impedance, the greater the output power. Only with sufficient audio input and power supply voltage/current can there be enough output power.Frequently Asked QuestionsSelecting the right power supply is essential, ensuring it is compatible with the board and has minimal ripple. A power supply with excessive ripple can lead to amplifier board issues, increased background noise, and electrical buzzing. Higher voltage results in greater current flow and higher output power. For instance, a 12V1A power supply can be used with 3-4 inch speakers.Having a power supply of 19V 5A or higher, with a size of 8-10 inches, is crucial. Insufficient voltage may lead to sound distortion when amplifying sound. Inadequate current can result in the speaker reducing voltage, causing abnormal operation or deteriorating sound quality.Explanation of different audio input options. This audio amplifier module offers two ways to input audio: via Bluetooth (BT) or AUX. Bluetooth takes precedence over AUX. Bluetooth can be connected in any mode. Once the Bluetooth connection is established, it enters Bluetooth mode, which also allows for automatic reconnection. If there is no Bluetooth connection, the module switches to AUX mode when an AUX cable is plugged in.Please remember to check that the Bluetooth connection of this module has been disconnected when using AUX mode.To control the overall sound level, turn the main volume knob. Turning the knob to the right increases the volume, while turning it to the left decreases it. The main volume setting affects the sound output of both the left and right speakers as well as the subwoofer.Is it normal for the sound to be faint, but when it gets louder, does it become muffled? The sound is not clear. Please lower the volume or switch to a power adapter with higher voltage.Even if the volume is low, if it gets louder, does the sound delay occur? This is because the input power is insufficient, and the power supply is intermittently turned off for protection. Please replace it with a higher power supply. Alternatively, if the gain is too high, the power amplifier board may overheat, triggering thermal protection. Reduce the power usage or enhance heat dissipation.The sound quality depends on various factors such as the amplifier module, power supply, sound source, and the overall audio system.In essence, the quality of sound is influenced by various elements of the audio system, including the audio transmission line, power supply, tone circuit, amplifier circuit, speaker, and the environment. Optimal sound quality is achieved when the sound source, power supply, amplifier module, and speakers are well-matched.