Hi,
I have this board:
I connected it to the speakers and powered it through USB but I have noticed this board doesn't play some parts of a sound that have low dB, is it possible to fix this issue?
I noticed the board has some free spaces to solder SMD components, what are they for exactly?
If this post is inadequate for "project Guidance" please tell me where I should place it.
All questions for the manufacturer!
Paul
Okay, sorry to bother then.
That's odd... What you're describing is a [u]Noise Gate[/u] effect, but that shouldn't be built-into a Bluetooth module. You might have a gate/squelch if the RF signal gets weak, but not if the audio signal gets week/quiet.
Maybe it's a feature to turn it off when there's no signal? (To save battery life.)
There's probably nothing you can do about it. I don't see any switches, pots, jumpers, or anything to "configure" or adjust the board and I assume there is no software configuration?
I noticed the board has some free spaces to solder SMD components, what are they for exactly?
Usually you'll see (small value) capacitors between the crystal terminals and ground. I don't know exactly why you usually need them, but if the board is working, this particular circuit works without them. ...Maybe they are installed when the manufacturer uses an alternate crystal.
The other part, I have no clue.
It's not unusual for a manufacturer to make multiple versions of a board, or multiple-different products using the same board (sometimes with different components).
Sometimes after the board is designed they discover a problem an a part has to be added (bummer) or they may discover that the board works with a part left-off. Actually, that's very common... Boards rarely work perfectly the first time and it's rare to fine a "Rev 1" or "Rev A" board in the hands of a customer.
If they discover an error on the board or they make a design change they'll usually use the existing boards if they can and they may, or may-not, re-design the boards for the next production run.
Thanks for answering DVDdoug, it really seems to be a Noise Gate then.
I'll see the datasheet of this IC's (If I find it), there may be a way to change the threshold of the noise gate.
Hi,
How loud or quiet are you playing your audio.
What impedance speakers are you driving?
Tom..... 
@TomGeorge It's 8 Ohm if I am not mistaken.
I usually only use the first 4 positions of the audio bar shown in the smartphone (it has 15 positions in total not counting with zero).
All I know so far about the board is that it uses a PAM8403 IC (datasheet https://www.diodes.com/assets/Datasheets/PAM8403.pdf) as an audio amp.
I think I could connect VDD to pin 5 forcing it not to mute.
By the way, I'm sorry for answering a decade later.
To determine the exact nature of your problem, try using a tone generator app on your phone - then you have control of the level (and frequency), so your testing becomes more objective.
For all we know, the output may not be suitable for driving 8R directly at low levels... many more per options that need you to explore.
