How to reduce the beep noise coming out of an MP3 module for my TDA2030 amplifier circuit project?

Question

After making a stereo circuit board with a TDA2030 and mobile aux as input, I wanted to connect an MP3/BT module to my own indigenous audio amplifier circuit which would make every action easier I supposed, but things went wrong.

In mono circuit, the Bluetooth does not output that highly annoying noise but I want it to be stereo.

Below are the pictures of my MP3 module:

The module has 5 modes which are:

1. Bluetooth mode
2. AUX mode.
3. Pendrive Mode
4. SDcard Mode
5. FM Radio mode.

In Bluetooth mode, the noise is produced much more than others, unbearable Bluetooth spike frequency sound, in AUX and Pendrive mode, the noise is quite low (bearable.)

In FM Radio mode, there is almost no noise.

Here is my circuit:

^{simulate this circuit – Schematic created using CircuitLab}

I also tried connecting some filters to the output of the MP3 module which were supposed to reduce noise.

Like this:

^{simulate this circuit}

That did not work at all.

When I connect the stereo circuit input directly to my mobile stereo output using headphone jack, it works very well until I connect the module again.

Any suggestions or helps please? Please point me my errors using a proper schematic which will make it easier to understand for me.

Answer 1

You are basically shorting out TDA2030 inputs to ground in AC via C18/C19. You need to add another resistors between pin 1 of each channel (IN+) and half of power supply (R3/R4 and R11/R12). Audio signal goes into pin 1 like you do now from a capacitor.

Look closely at TDA2030 datasheet for single supply schematics.

Answer 2

Some Bypass capacitors of 104 pf connecting to the power pins (+ve and ground) of the MP3 module solved this problem. Noise is quite low now.

Answer 3

I did the modification and coupled to a mixer amp without any problems. There was a slight hissing from HF which I compensated by reducing the above 15 kHz audio range from graphic equalizer but can also be done by a 100 pF bypass filter across the input and also increasing lower frequency response by increasing value of C1 and C10 to 10 uF.