Is the PCB ok?...

[epilot]

Hi guys,

Is there somebody to let me plz to know if the ground plane in the below circuit (the circuit is an pre-AMP) can causes any ground loop too? I fear that the route I have shown in yellow causes an ground loop. What is your idea plz?

Thank

[MagicBox]

A 'local' loop that size would be the least of your concerns grounding your design. It's hard to see what each ground path is, but as it is now, your groundplane is not creating an optimal 'star' ground right now.

[AndrewT]

The black must be copper.
Try drawing on the input signal route from Source Hot Flow/Input to Source Cold Return.
Does that route have a small loop area?
Does that route pass near other higher current traces or past spiky current traces (dirty ClassAB currents)?

If the layout fails either of these tests then start again, iof it passes then try tracing out the speaker route from speaker Return to Speaker Hot as it passes through the various components and traces.
Repeat the same tests.

Finally, trace out the PSU current supply route from smoothing caps to output devices and back to smoothing caps. Remember you have two separated but connected PSU current routes. +ve current and -ve current. these plus Zero Volts Return should be run as a small loop area triplet.

[epilot]

Originally Posted by AndrewT

The black must be copper.
Try drawing on the input signal route from Source Hot Flow/Input to Source Cold Return.
Does that route have a small loop area?
Does that route pass near other higher current traces or past spiky current traces (dirty ClassAB currents)?

If the layout fails either of these tests then start again, iof it passes then try tracing out the speaker route from speaker Return to Speaker Hot as it passes through the various components and traces.
Repeat the same tests.

Finally, trace out the PSU current supply route from smoothing caps to output devices and back to smoothing caps. Remember you have two separated but connected PSU current routes. +ve current and -ve current. these plus Zero Volts Return should be run as a small loop area triplet.

Hi Andrew,

thanks for your reply.

Actually it was hard to me to undestand your means, So I tried to figiure the properties a bit more in below pic.

Fourthermore I have got an important question and hope you plz kindly help me out about it. In the below pic you can see thtt output. I want to connect this output to the input of an power amplifier. Now plz tell me if I should use just one wire to do so, Or should I use 2 wires one connected to the gound (ground plane) of the below circuit?? The grounds of the below pic and the power amplifier is connected to a star ground...

Thanks a lot

[epilot]

No idea plz?

[nigelwright7557]

Keep the inputs and outputs at opposite ends and make them connect to ground in the middle of the pcb at one point.

[epilot]

Originally Posted by nigelwright7557

Keep the inputs and outputs at opposite ends and make them connect to ground in the middle of the pcb at one point.

I think I do not need to create a STAR ground for the output and specially for the input grounds when I have a ground plane...?

[nigelwright7557]

Originally Posted by epilot

I think I do not need to create a STAR ground for the output and specially for the input grounds when I have a ground plane...?

But you dont want high power output signals near input signals or you will get feedback. The grounds should split at the terminal to go one way to inputs and the other way to outputs.

[epilot]

Originally Posted by nigelwright7557

But you dont want high power output signals near input signals or you will get feedback. The grounds should split at the terminal to go one way to inputs and the other way to outputs.

Sorry I did not get the red one. can you plz kindly explain it or at least show me your meaning by a pic?

Thankd

[epilot]

Originally Posted by nigelwright7557

But you dont want high power output signals near input signals or you will get feedback. The grounds should split at the terminal to go one way to inputs and the other way to outputs.

Sorry I did not get the red one. can you plz kindly explain it or at least show me your meaning by a pic?

Thanks