how to choose common connection of ground in PCB design for audio board

[dann11]

Hi! I am working on a PCB design, which is for audio DSP, I want to avoid ground loops. How should I connect the grounds? Where should their common ground connection be? any suggestion guys?

 

[KlausST]

Hi,

We are talking about a PCB only ... and want to avoid only GND loops on this PCB. We don´t talk about external GND loops.
--> If this is not the case, then post a picture of your application with all the nodes that may casue GND loops.

On the PCB:
there will be diffferent sections:
* analog input
* ADC
* digtal processing
* digital interfaces
* DAC
* analoig output
* power supply
* something else.

Place those sections in a way that both analog sections are free from GND current caused by the other (mostly digital sections).
Do a raw placement of the sections, print it on a sheet of paper, then use a text marker and mark the expected gND current paths. Maybe with different colors.

There is no general rule. Fur sure "start point" connections may avoid the errors caused by GND loops.
Maybe you can avoid or limit GND loops with placing resistors in the GND lines. But you need some experience to find out where to place them and if you need to modify your circuitry to "compensate" the voltage across those resistors.
Or you may use completely isolated sections.

Klaus