Manuals+

ZK-MT21 2.1 Channel Bluetooth Amplifier Module

Product Parameters

Product Name
2.1 channel Bluetooth audio amplifier module
Product Model
ZK-MT21
Bluetooth Version
5.0 (unobstructed, 10 meters)
Input Sensitivity
500mV
Input Method
AUX + Bluetooth
Number of Channels
2.1 channels
Power Amplifier Chip
TPA3116D2 (with AM interference suppression function)
Adapted Power Supply
DC 12-24V / 5A or above (higher voltage yields greater output power)
Adapted Speaker
20-100W, 4-8 Ω
Output Power
Left and right channels: ≤ 50W; Subwoofer: ≤ 100W
Protection Mechanism
Overvoltage, undervoltage, overheating, DC detection, short circuit protection
Product Size
120mm * 100mm * 20mm
Product Weight
Approximately 256g (including packaging)

Tip: Sufficient output power requires adequate audio input and power supply voltage/current. Higher power supply voltage, lower horn impedance, and greater output power are achieved. Ensure the adapter power supply's capacity exceeds the amplifier's actual working power.

Assembly Drawing

The assembly drawing illustrates the components of the ZK-MT21 module. Key parts include:

  • PCB board (labeled ZK-TB21, 50W*2+100W, TREBLE - BASS REGULATION, 2.1 CHANNEL POWER AMPLIFIER)
  • Upper cover plate
  • Lower cover plate
  • M2x4mm screws (x8) for securing the cover plates
  • M2x16 copper pillars (x4) and M2x5+4 copper pillars (x4) for mounting the PCB
  • Power adapter (represented by a screwdriver and a power input connector)
  • Button caps (x5) for potentiometers
  • A screwdriver is shown for assembly.

The diagram shows how the upper and lower cover plates enclose the PCB, with screws and pillars used for assembly.

Function and Controls

The front panel of the amplifier module features several controls and input/output connectors:

  • Power Input: Located on the rear/side, typically a 5.5x21DC head and a 2P terminal.
  • Audio Input (Bluetooth AUX): A Bluetooth symbol indicates Bluetooth connectivity, and an AUX input is available. Bluetooth connection is prioritized.
  • Subwoofer Controls:
    • Subwoofer Frequency (FREQ): Knob for adjusting the frequency range (20-200Hz).
    • Subwoofer Volume: Knob for adjusting the subwoofer's volume.
  • Left and Right Channel Controls:
    • Left and Right Channel Treble: Knob for adjusting the treble for left and right channels.
    • Left and Right Channel Bass: Knob for adjusting the bass for left and right channels.
  • Master Volume: A large knob labeled "MAIN VOLUME" controls the overall sound level for all channels.

The diagram also labels the audio output paths: "Right", "Left vocal tract", and "subwoofer".

Frequently Asked Questions (FAQ)

1. How to choose a power supply?

Selecting the correct power supply is crucial. The power supply should have a low ripple. A high-ripple power supply can cause the amplifier board to malfunction, leading to bottom noise and electric current sounds. Higher voltage and current generally provide more output power. For example, 12V 1A might suffice for 3-4 inch speakers, while 19V 5A or higher is recommended for 8-10 inch speakers. Insufficient voltage can cause sound distortion, and insufficient current can lead to abnormal speaker operation or sound quality deterioration.

2. Introduction to audio input modes

This module supports two audio input methods: Bluetooth and AUX. Bluetooth connection has priority. Once a Bluetooth connection is established, the module operates in Bluetooth Mode and supports automatic reconnection. If no Bluetooth connection is active, AUX input is used when a cable is inserted. It is important to disconnect Bluetooth when using AUX mode.

3. How to adjust the main volume?

The main volume knob adjusts the overall sound level. Turning it clockwise increases the volume, and counter-clockwise decreases it. The main volume affects the output of the left and right channels, as well as the subwoofer.

4. It's okay if the sound is low, but when the sound becomes louder, there is a phenomenon of cloudy sound?

This indicates sound distortion. Try reducing the total volume or using a higher voltage adapter power supply.

5. It's okay if the sound is low, but when the sound becomes louder, there is a phenomenon of sound lag?

This is likely due to insufficient input power, causing the power supply to intermittently shut off for protection. Replace it with a higher-power supply. Alternatively, excessive heat generation in the power amplifier board might be causing thermal protection to engage. In such cases, reduce power usage or improve heat dissipation.

6. What factors are related to the quality of sound?

Sound quality depends on multiple factors beyond just the amplifier module. These include the power supply, the sound source, the audio transmission line, the tone circuit, the amplifier circuit, the speakers, and the surrounding environment. Optimal sound quality is achieved when the sound source, power supply, amplifier module, and speakers are well-matched.

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