DAJUNGUO ZK-HT21 Bluetooth Power Amplifier Board Installation Guide

DAJUNGUO ZK-HT21 Bluetooth Power Amplifier Board Installation Guide

As a compact power amplifier board, ZK-HT21 uses the HIFI chip TDA7498E released by ST. This makes the ZK-HT21 power amplifier board perform well in both output power and HIFI sound quality. Regarding the appearance of the product, we are more concerned about the internal quality of the product. We spend a large proportion of the funds on the realization of the product function, instead of using a lot of funds to design a flashy shell for the product, you see how its packaging box is. Simple, haha…

But, please don’t be confused by his simple appearance, this guy has a power output of up to 160W-x-2+220W, Bluetooth 5.0, AUX, USB sound card function, U disk playback function…

Product Parameter

• Product Name: 2.1 channel Bluetooth audio power amplifier module
• Product Model: ZK-HT21
• Bluetooth Version: 5.0 (unobstructed, 49 feet)
• Input Method: AUX+Bluetooth+USB (switching mode and song by dial button)
• Number of Channels: 2.1 channels (left channel + right channel + subwoofer)
• Power Amplifier chip: TDA7498E
• Adapter Power Supply: DC15ZI36V (under voltage protection below 9V, 12V power supply can also be supported)
• Adapted Speakers: 30-200W, 4-80
• Output Power: L& R 160W (MAX) , Subwoofer:220W (MAX)

Product Function Distribution Description

Press the dial button in the middle
Short press: pause/play
Long press: switch mode (USB/BT/AUX)

Turn the dial button to the left
Short press: previous song
Long press: volume –

Turn the dial button to the right
Short press: next song
Long press: volume +

Notice:

1. The USB interface only supports U disk or memory card to play music (the U disk format needs to be FAT32, and the maximum support is 32GB). At the same time, the USB interface does not support direct connection to a computer through a USB data cable.
2. The volume control of the dial button and the volume control of the main volume are in series. If the two volume controls are at 100% and 80% respectively, then the actual volume output is 80%, only when both volume controls are at 100% There is 100% volume output. You can control the volume in a limited range through the dial wheel to prevent the output power from being too loud or the sound being too loud.
3. The up and down curve function of the wheel is only used in U disk or Bluetooth mode. If the AUX input is used, the up and down function of the wheel will be invalid.

Q&A

1. How to select the power supply?
   The power supply matched with the board is very important. The ripple of the selected power supply must be small. The power supply with large ripple will cause the noise at the bottom of the power amplifier board to become larger and there is current sound. The higher the voltage, the greater the current and the more sufficient the output power. If you only have 12V 1 A, you can bring a 3-4-inch speaker. If you are above 19V 5A, there is no problem with 8-10 inches. You must pay great attention to the power supply. If the voltage is too low, it is easy to cause sound dis-tortion after sound amplification. If the current is too small to bring up, the horn will pull down the voltage, work ab-normally or sound quality will become worse.
   It is recommended to use 18V19V24V power supply with current above 8A or 32V10A power supply. If you only have 12V 15V 2A power supply, you can also use it, but the power is small. When you use it, the volume is close to the maximum, which may distort and affect the sound quality. If you want to get the maximum output power, it is recommended to use an adapter above 36V1 OA, a 160W — 200W 40 speaker, and adjust the volume to the maximum.

2. How to select speaker?
   About speaker type: commonly used speakers are generally 4-8 ohms, which can be used. The left and right channel speakers need to be connected with full frequency speakers or medium and high frequency speakers, and the power is between 30W-200W. The subwoofer speaker cannot be connected to an ordinary speaker, but needs to be connected to a speaker with subwoofer speaker, with a power of 50-200W. The submergence frequency of sub-woofer horn shall be at least 50Hz.
   If your speaker power is small, such as between 20W-SOW, it can also be used. You need to reduce the power supply voltage to prevent burning the horn after loud. For example, choose a power supply below 15V. The higher the se-lected voltage, the greater the sound or power that can be output. The speaker power is not easy to exceed 200W, otherwise the sound quality will be affected.

3. Introduction to audio input mode.
   The audio power amplifier module has three audio input modes: BT input, AUX audio input and USB flash disk input. In BT mode, if an audio cable or USB flash disk is inserted, it will automatically switch to audio input mode or USB flash disk input mode, and BT mode has the lowest priority. When the audio cable or USB flash disk has been insert-ed, you can also use the dial key to switch the mode.

4. How to adjust the total volume?
   The main-volume knob is used to adjust the total volume. The total right-hand volume increases and the total left-hand volume decreases. The total volume affects the volume of the left and right channels and subwoofer.

5. How to adjust the left and right channel treble and bass?
   The R & L channel bass knob controls the bass. The right-hand bass is enhanced and the left-hand bass is attenuat-ed. When the knob is in the middle position, the bass is neither enhanced nor attenuated.
   The R & L channel treble knob controls the treble. The right-hand treble is enhanced and the left-hand treble is at-tenuated. When the knob is in the middle position, the treble is neither enhanced nor attenuated.
   Note: if the treble and total volume are adjusted to the maximum at the same time, it is easy to cause power amplifi-er protection and sound jamming. Lower the treble or turn the main-volume knob on the right to the left to reduce the total volume.

6. How to adjust the subwoofer?
   Subwoofer – volume knob controls the volume of subwoofer. The right-hand volume increases and the left-hand volume decreases.
   The subwoofer-freq knob controls the cutoff frequency of the subwoofer. The right rotation frequency increases and the left rotation frequency decreases. The frequency adjustment range is 20HZ-200HZ. It is normal that the right- handed frequency increases and the part with high frequency is released, and the sound of subwoofer will become larger.

7. It’s ok to have a small voice, but after the voice becomes louder, there will be the phenomenon of sound turbidity. The sound is distorted, please turn down the total volume or change the adapter to a higher voltage level.

8. It’s ok to have a small voice, but when the voice gets louder, there will be the phenomenon of sound lag. If the input power is insufficient and the power is protected by its own intermittent power failure, please replace the power with a more powerful one.Or the power is too big, the power amplifier heating seriously, appeared the heat protection situation, reduce the power use or strengthen the heat dissipation.

9. What factors are associated with sound quality?
   The quality of sound is not only related to the power amplifier module, but also to the power supply, sound source and the whole sound system.Basically every link of the sound system will affect the sound quality, among which the main link is the audio transmission line, audio power supply, tone circuit, amplifier circuit, speakers and the sur-rounding environment.The sound quality is best when the sound source, power supply, amplifier module and the speaker are matched.

Power Output Comparison Table(@1KHG)

Power**
15V| SQ| 40w+40w| SQ|
40| 70w+70w| 40| 100w
24V| SQ| 90w+90w| 80|
40| 120w+120w| 40| 160w
36V| SQ| 110w+110w| SQ|
40| 160w+160w| 40| 200w
30| | 30| 220w

Tip: when the audio signal input is large enough and the power supply voltage / current is large enough, there will be enough output power!
The higher the power supply voltage, the greater the output power, the smaller the horn impedance, and the greater the output power!
Please ensure that the power of the adaptive power supply is greater than the actual working power of the power amplifier!

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