Why is there so much noise on my bluetooth speaker setup?

Thread Starter

kmeyer

Joined Oct 10, 2019
10
With this wiring the noise is brutal. However, if I remove the power to the Bluetooth module from the l7805cv, and instead use the microusb power socket on the bt module the noise goes away. Are my connections to blame? Is it the voltage regulator?
Any advice would be appreciated.
Thanks.

https://streamable.com/o8lpcv
 

KeithWalker

Joined Jul 10, 2017
2,354
You don't give us very many clues to help you. The picture conveys nothing to me and my crystal ball is a little foggy tonight.
Give us the details of what modules and power supplies you are using, what your signal source is and a diagram of the wiring and we may be able to help.
 

Audioguru again

Joined Oct 21, 2019
4,693
ALL audio amplifiers use shielded audio input cables. You use ordinary wires that are antennas that pickup interference.
What is the amplifier part number?
 

Thread Starter

kmeyer

Joined Oct 10, 2019
10
You don't give us very many clues to help you. The picture conveys nothing to me and my crystal ball is a little foggy tonight.
Give us the details of what modules and power supplies you are using, what your signal source is and a diagram of the wiring and we may be able to help.
apologies, hope this helps....
1649719685360.png
 

KeithWalker

Joined Jul 10, 2017
2,354
That helps a lot. What kind of noise are you getting? is it a low frequency hum or a sharp crackling noise? What is supplying the 12VDC? Is it a wallwart? What current is it rated for? I suspect that it is the source of the noise. Try connecting a 100 uF 25V electrolytic capacitor across the 12V (observe the polarity) and see if it makes a difference.
 

Thread Starter

kmeyer

Joined Oct 10, 2019
10
That helps a lot. What is supplying the 12VDC? Is it a wallwart? What current is it rated for? I suspect that it is the source of the noise. Try connecting a 100 uF 25V electrolytic capacitor across the 12V (observe the polarity) and see if it makes a difference.
i googled wallwart. yes, it's a wallwart

PXL_20220411_233906985.jpg

What do you recommend as a power supply?
 

Thread Starter

kmeyer

Joined Oct 10, 2019
10
That helps a lot. What kind of noise are you getting? is it a low frequency hum or a sharp crackling noise? What is supplying the 12VDC? Is it a wallwart? What current is it rated for? I suspect that it is the source of the noise. Try connecting a 100 uF 25V electrolytic capacitor across the 12V (observe the polarity) and see if it makes a difference.
Kind of a crackling hum. You can hear the noise for yourself. Here's a recording from my original post: https://streamable.com/o8lpcv
 
Last edited:

Audioguru again

Joined Oct 21, 2019
4,693
I think the noise is the switching of the power supply. Use a linear power supply instead and use shielded audio input cables.
The 5V regulator feeding the Bluetooth receiver might not properly filter noise from the power supply.

With a 12V supply, the class-D TPA3110 amplifier produces about 8W per channel into 8 ohms speakers at low distortion, or 12W per channel into 4 ohms speakers.
 

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Thread Starter

kmeyer

Joined Oct 10, 2019
10
That helps a lot. What kind of noise are you getting? is it a low frequency hum or a sharp crackling noise? What is supplying the 12VDC? Is it a wallwart? What current is it rated for? I suspect that it is the source of the noise. Try connecting a 100 uF 25V electrolytic capacitor across the 12V (observe the polarity) and see if it makes a difference.
Hello,

Also, are you using the recommended capacitors for decoupling on the LM7805?
View attachment 264972

Bertus
I've ordered some caps. I'll need to research how to solder up what's in that circuit diagram.
Thanks everyone.
 
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