The PAM8403 amplifier is very noisy

Hi Gerald,

Thanks for the info, that part looks much better than the 8403. No reason to use that old part anymore. I can't recall the reason I had the 8403 board, I think I got it several years ago.

You're welcome.

Oh, yes me too - I also have toys I can't remember why I have it. :)

You mentioned the Vref _pin and -capacitor:

It is important to know that this pin is a bi-directional pin.

In the datasheet is descripted you need a X7R cer. cap. between 470n to 1u.

>>> Analog Reference Bypass Capacitor (CBYP)
The Analog Reference Bypass Capacitor (CBYP) is the most critical capacitor and serves several important functions. During start-up or recovery from shutdown mode, CBYP determines the rate at which the amplifier starts up. The second function is to reduce noise caused by the power supply coupling into the output drive signal. This noise is from the internal analog reference to the amplifier, which appears as degraded PSRR and THD+N.
A ceramic bypass capacitor (CBYP) with values of 0.47μF to 1.0μF is recommended for the best THD and noise performance. Increasing the bypass capacitor reduces clicking and popping noise from power on/off and entering and leaving shutdown.

>>>

But on the EMB is mounted a 100n X7R cap. This value is too small.

This pin, Vref can modulate the signal through the signal path if that Vref value is not stabile. 
Noise and popping noise signals are going to the amplifier.
This cap. must be mounted very close to the pin and the GND must be a polygon field. - The polygon should be around the IC as well.

Hi, I'm a little late with the reply, I don't have much time during the week. 
I added pictures to the post.
I'll experiment with the USB power supply part.
I think LEDs (there are 7 per speaker) of this type consume enough mA (tens), and since I want to create some visual effects, I'm basically witnessing a "symphony" of noise.

The PAM8403 module of this type is a little noisy (it's not for nothing that it costs very little), but it's clear to me that the LEDs produce a very sharp sound (I would describe it as a very annoying mosquito sound, I know it sounds strange what I'm saying ).

Thank you, I will check that filter circuit.
The PCB version is a bit homemade, so I can't make any claims.

Not really, but maybe I don't need to go that far. I can also try other 5V powered circuits.

I experimented a little by inserting a filter, I didn't use the same speakers (it's more difficult than it seems) but I noticed some reduction in "noise".
Waiting for my PAM8406 version to arrive which should be improved on this side.

I'm waiting for the PAM8406 version which should not be so noisy.
I didn't achieve much using the ferrite bead + capacitors filter.

I did a test, I used the 5V power supply from the board to power another circuit also with addressable LEDs, and the noise is reduced (not by much) than when using LEDs that are already on the speaker. The noise source (addressable LEDs) being further away has some positive effect.

Can you make photos of your assembled amp., that show us details about your built?