DAJUNGUO ZK-ST21

Download PDFFree PDF. The Save button below keeps a bookmark and private notes in your account.

DAJUNGUO ZK-ST21 TPA3221 Bluetooth Power Amplifier Board User Manual

Model: ZK-ST21 | Brand: DAJUNGUO

1. Introduction

This manual provides detailed instructions for the installation, operation, and maintenance of your DAJUNGUO ZK-ST21 TPA3221 Bluetooth Power Amplifier Board. This 2.1 channel audio amplifier module is designed to deliver high-quality sound with a subwoofer output, offering versatile input options and tone control. Please read this manual thoroughly before using the product to ensure proper function and safety.

2. Safety Information

  • Ensure the power supply voltage is within the specified range of 12V-30V DC. Using an incorrect voltage can damage the device.
  • Always connect speakers and input sources before connecting the power supply.
  • Avoid exposing the device to moisture, extreme temperatures, or direct sunlight.
  • Do not attempt to disassemble or modify the amplifier board. Refer all servicing to qualified personnel.
  • Ensure proper ventilation around the amplifier to prevent overheating.

3. Product Overview

The ZK-ST21 is a 2.1 channel audio amplifier board featuring the TPA3221 chip, providing dedicated outputs for left, right, and subwoofer channels. It includes multiple input methods and comprehensive tone controls.

Diagram of ZK-ST21 amplifier board with labeled components

Figure 3.1: ZK-ST21 Component Layout. This image displays the amplifier board with various components labeled, including power input, speaker outputs, input jacks, and control knobs. Key labels include Subwoofer Frequency, Subwoofer Volume, R&L Treble, R&L Bass, Main Volume with Switch, MIC Extension Interface, LINE IN Input (3.5mm Audio Socket), USB Drive/Sound Card Input, Right Speaker, Left Speaker, Subwoofer Speaker, and Power Input (12-30VDC).

Key Features:

  • 2.1 Channel Output: Dedicated channels for stereo (Left/Right) and a subwoofer.
  • High Power Output: Up to 100W per stereo channel and 200W for the subwoofer (peak power).
  • Multiple Input Modes: Supports Bluetooth, AUX (3.5mm), and USB disk/sound card input.
  • Tone Control: Independent controls for R&L Treble, R&L Bass, and Subwoofer Frequency.
  • Volume Control: Separate controls for Main Volume and Subwoofer Volume.
  • Wide Voltage Range: Operates on 12V-30V DC power supply.

4. Setup

4.1 Power Supply Connection

The amplifier requires a DC power supply between 12V and 30V. For optimal performance, a 24V-28V DC power supply with a current of 10A or above is recommended.

  • Connect the positive (+) terminal of your DC power supply to the 'DC IN' positive terminal on the board.
  • Connect the negative (-) terminal of your DC power supply to the 'DC IN' negative terminal on the board.

4.2 Speaker Connection

Ensure your speakers are compatible with the amplifier's output specifications.

  • Left and Right Channels: Connect 3-8Ω speakers, up to 100W each, to the 'Left Speaker' and 'Right Speaker' terminals.
  • Subwoofer Channel: Connect a 2-8Ω subwoofer, up to 200W, to the 'Subwoofer Speaker' terminal.
Diagram showing power supply, speaker, and maximum power specifications

Figure 4.1: Power and Speaker Specifications. This image details the input method (Bluetooth+AUX+USB disk/sound card), power amplifier chip (Two TI original TPA3221), adapted power supply (12-30VDC, recommended 24-28V 10A+), adapted speaker types (Left/Right: 3-8Ω up to 100W; Subwoofer: 2-8Ω up to 200W), and maximum power output at different impedances and voltages.

4.3 Input Source Connection

  • AUX Input: Connect your audio source (e.g., computer, TV, MP3 player) to the 'LINE IN Input' (3.5mm Audio Socket) using a 3.5mm audio cable.
  • USB Input: Insert a USB flash drive (FAT32 format, up to 32GB) into the 'USB Drive/Sound Card Input' port.
  • Bluetooth: No physical connection needed. Refer to Section 5.2 for pairing instructions.

5. Operating Instructions

5.1 Power On/Off and Volume Control

  • Power On: Rotate the 'Main Volume with Switch' knob clockwise until it clicks and the indicator light turns on.
  • Power Off: Rotate the 'Main Volume with Switch' knob counter-clockwise until it clicks and the indicator light turns off.
  • Main Volume: Adjust the overall output volume by rotating the 'Main Volume with Switch' knob.
  • Subwoofer Volume: Use the 'Subwoofer Volume' knob to adjust the dedicated subwoofer output level.

5.2 Input Mode Selection and Bluetooth Pairing

The amplifier supports multiple input modes. The device automatically switches between inputs when a new source is detected or selected.

Image showing multiple input modes: Bluetooth, 3.5mm Aux, USB Mode

Figure 5.1: Multiple Input Modes. This image illustrates the three primary input methods: Bluetooth for wireless connection, 3.5mm Aux for wired connection to devices like computers or TVs, and USB Mode for playing audio from a FAT32 formatted USB flash disk (up to 32GB).

  • Bluetooth Pairing:
    1. Ensure the amplifier is powered on.
    2. On your mobile device, enable Bluetooth and search for available devices.
    3. Select 'ZK-ST21' (or similar name) from the list to pair. A confirmation sound may be heard.
    4. You can change the Bluetooth name and password through a dedicated application if available (refer to product packaging or manufacturer's website for app details).
  • AUX Input: Connect your audio device to the 3.5mm 'LINE IN' jack. The amplifier should automatically switch to AUX mode.
  • USB Input: Insert a compatible USB flash drive. The amplifier will automatically detect and play audio files.

5.3 Tone Control

  • R&L Treble: Adjust the high-frequency response of the left and right stereo channels.
  • R&L Bass: Adjust the low-frequency response of the left and right stereo channels.
  • Subwoofer Frequency: Adjust the crossover frequency for the subwoofer output, controlling which low frequencies are sent to the subwoofer.

6. Maintenance

  • Keep the amplifier board clean and free from dust. Use a soft, dry cloth for cleaning.
  • Do not use liquid cleaners or solvents, as they may damage the components.
  • Ensure all connections are secure and free from corrosion.
  • Store the device in a cool, dry place when not in use for extended periods.

7. Troubleshooting

ProblemPossible CauseSolution
Amplifier does not power on (no lights, no sound).
  • Power supply not connected or faulty.
  • Main volume knob not turned on.
  • Incorrect power supply voltage/current.
  • Check power supply connection and ensure it's working.
  • Rotate the 'Main Volume with Switch' knob clockwise until it clicks.
  • Verify power supply is 12V-30V DC and provides sufficient current (e.g., 24V 10A).
No sound from speakers.
  • Speaker connections loose or incorrect.
  • Input source not connected or selected.
  • Volume levels too low.
  • Faulty audio cable.
  • Check all speaker wire connections for correct polarity and secure fit.
  • Ensure the input source is properly connected and the correct input mode is active.
  • Increase Main Volume and Subwoofer Volume.
  • Try a different audio cable.
Sound cuts off at high volume.
  • Insufficient power supply current.
  • Overheating.
  • Speaker impedance mismatch.
  • Ensure your power supply can deliver enough current (e.g., 10A or more for 24V).
  • Check for proper ventilation around the amplifier.
  • Verify speaker impedance matches recommended values (Left/Right: 3-8Ω; Subwoofer: 2-8Ω).
Poor sound quality or low output at 12V.
  • Lower input voltage results in reduced output power.
  • The amplifier's maximum output power is significantly reduced at lower input voltages. For higher power output, use a power supply closer to the 24V-30V range. For example, at 12V with an 8-ohm speaker, output may be around 10W.
Bluetooth connection issues.
  • Device not in pairing mode.
  • Interference.
  • Distance too far.
  • Ensure the amplifier is powered on and discoverable.
  • Move closer to the amplifier and away from other wireless devices.
  • Try restarting both the amplifier and your Bluetooth device.

8. Specifications

Diagram showing product dimensions of ZK-ST21 amplifier board

Figure 8.1: ZK-ST21 Product Dimensions. This image provides the physical dimensions of the ZK-ST21 amplifier board, showing a length of 121mm (4.76in), width of 100mm (3.93in), and height of 25mm (0.98in). The board itself measures approximately 92mm (3.62in) by 77.5mm (3.05in).

FeatureSpecification
Model NumberZK-ST21
Amplifier ChipTPA3221
Channels2.1 (Left, Right, Subwoofer)
Output Power (Max)Left/Right: 100W x 2 (4Ω, 30V); Subwoofer: 200W (2Ω, 30V)
Supply Voltage12V - 30V DC (Recommended: 24V-28V DC, 10A+)
Speaker ImpedanceLeft/Right: 3-8Ω; Subwoofer: 2-8Ω
Input MethodsBluetooth, AUX (3.5mm), USB Disk/Sound Card
USB Disk FormatFAT32 (up to 32GB)
Item Dimensions (L x W x H)12.1 x 10 x 2.5 Centimeters
Item Weight290 Grams
Country of OriginChina
UPC194852393783

9. Warranty and Support

For warranty information and technical support, please refer to the documentation included with your purchase or contact the manufacturer directly through their official website or customer service channels. Keep your purchase receipt as proof of purchase for any warranty claims.

Ask a question about this manual

Ask about setup, troubleshooting, compatibility, parts, safety, or missing instructions. Manuals+ will review the question and use this page’s manual context to help answer it.

After a successful submission, we securely hash the supplied account or form email before sending it to Microsoft Advertising for conversion attribution. Privacy details.