2.1 Channel Amplifier Bluetooth Digital Power Amplifier Amp Module 50W*2+100W Unassembled ZK-TB21

2.1 Channel Amplifier Bluetooth Digital Power Amplifier Amp Module 50W*2+100W Unassembled ZK-TB21

Package Included:
- 1 x Set of Power Amplifier

Note: Please note that assembly of its shell is needed.

1. How to choose power supply?
The power supply of the board is very critical. The ripple of selected power supply must be small. A power supply with large ripple will cause the noise of the bottom of power amplifier board to become larger and there will be current sound. The higher the voltage, the higher the current, and the more output power. If you only have a 12V 1A power supply, this can drive 3-4 inch speakers. If your power supply is above 19V 5A, drive 8-10 inch speakers. Power supply must be highly valued. If the voltage is too low, the sound is easily distorted after amplification. If the current is too small to drive speaker, the voltage will be pulled down, the work is not normal or the sound quality is deteriorated.

Recommend to use 18V 19V 24V power supply, current 5A or more. If you only have 9V 12V or 1A 2A power supply, it can also be used but the power is small. When you use volume close to the maximum, it may be distorted and affect sound quality.

2. How to choose speakers?
About speaker type: 4-8 ohm speakers can be used. Left and right channel speakers need to be connected to full-range speakers or high-frequency speakers, and the power is between 20W-100W. Subwoofer speaker can not be connected to ordinary speaker, you need to connect the speaker with the subwoofer speaker, the power is between 20-100. The dive frequency of the subwoofer speaker should be at least 50Hz.

If your speaker power is small, for example, between 20W-50W, it can also be used. The power supply voltage needs to be lower to prevent the speaker from being burned after the sound is amplified. If you are a 50W-100w speaker, don't worry about the speaker burnout, you can choose 12-24V power supply, the higher the voltage, the greater the output sound or power. Speaker power is not easy to exceed 100W, otherwise it will affect the sound quality.

3. Introduction of audio input mode:
This audio power amplifier module has two audio input methods: one is Bluetooth input, and the other is AUX input, Bluetooth mode has priority. No matter in which mode Bluetooth can be connected. As long as the Bluetooth connection is successful, it is in Bluetooth mode, and the Bluetooth mode supports automatic connection back. When the Bluetooth is not connected, it is in AUX mode. It should be noted that when using AUX mode, you need to confirm that the Bluetooth connection of this module has been disconnected.

4. How to adjust the master volume?
MAIN-VOLUME knob adjusts the master volume. Turn it to the right side to increase the volume. Turn it to the left side to decrease. The master volume affects both the left and right channels and the volume of the subwoofer.

5. How to adjust the high and low sound of left and right channels
R&L CHANNEL-BASS knob controls bass. Rotate it to the right to enhance bass. Rotate to the left and the bass is attenuated. When the knob is at the rightmost position, the bass is not enhanced or attenuated.

R&L CHANNEL-TREBLE knob controls treble. Rotate it to the right to enhance the treble. Turn it to the left to make treble attenuation. When the knob is in the middle position, the treble is neither enhanced nor attenuated.

Pay attention to when adjusting the high and low sounds: When it s in treble or bass state, knob is is adjusted to near maximum, if the sound is distorted, it means that the gain of treble or bass adjustment is too large. At this time, you need to turn the treble or bass knob to the left to reduce the gain or rotate MAIN-VOLUME knob to the left to reduce the total volume.

6. How to adjust the subwoofer?
SUBWOOFER-VOLUME knob controls the volume of subwoofer. Turn the knob to the right to increase the volume. Turn it to the left to decrease.

SUBWOOFER-FREQ knob controls the cutoff frequency of subwoofer. Turn the knob to the right to increase frequency. Turn it to the left to decrease frequency. Frequency adjustment range is 20Hz-200Hz.

7. Sound is small and fine. After the sound becomes louder, the sound becomes muddy?
The sound is distorted, please turn down the total volume or change power adapter with higher voltage level.

8. The sound is small and fine. After the sound becomes louder, the sound freezes?
The power of input power supply is insufficient, the power supply itself is intermittently powered off. Please replace the power supply with a larger power; or the power is too large, the power amplifier board heats up seriously, and there is a case of thermal protection. Reduce power or strengthen heat dissipation.

9. What factors are related to the sound quality?
Sound quality is related to the power amplifier module, and also to power supply, sound source and entire sound system. Basically, every link of audio system will affect sound quality. The main links include audio transmission line, audio power supply, tone circuit, power amplifier circuit, sound box and surrounding environment. Only when the sound source, power supply, power amplifier module and speaker match, the sound quality is the best.