Quick guide on Grounding

[Vostro]

Ive been trying hard to make a nice amp, but struggle,
I don't know anyone in my area I could ask so I'm here again for help.

I'm struggling with grounding between all different boards in chassis as
I posted in other thread, http://www.diyaudio.com/forums/solid-state/216569-ground-wiring-advice-needed.html

After reading this thread, sadly im sill not sure,
I've posted here cause these questions relate to my grounding on the PCB itself,

I wanted to know if any of these two schemes are correct.
If there needs changes Please Help.

Thanks so much

 

[john_ellis]

Hi

I think a common mistake is to separate the power capacitors. In the diagram yhou show, Vostro, are the caps the main filters or supplementary (local) caps on the amp board?

The best performance I have had with grounding is to join the common terminals of the capacitors with a short length of thick wire (preferably copper bus) and use the centre point of this as a star earth. The transformer inputs also joins here to keep this "star ground" as common as possible. This keeps the impedances low. Any wiring between the cap ground terminals will induce noise.

I don't think you can get a better ground impedance than this approach. I too have had to turn a preamp on to hear whether the amp is live or not.

The amp has two grounds - one for the power taking the local capacitors to the star and the other for the input stage to the star.

Cheers
John

 

[Vostro]

The caps shown are 10 000uf and are the only smoothing caps with just bridge off board, I'm not sure if I'll stay with this approach.

 

[OnAudio]

Ive been trying hard to make a nice amp, but struggle,
I don't know anyone in my area I could ask so I'm here again for help.

I'm struggling with grounding between all different boards in chassis as
I posted in other thread, http://www.diyaudio.com/forums/solid-state/216569-ground-wiring-advice-needed.html

After reading this thread, sadly im sill not sure,
I've posted here cause these questions relate to my grounding on the PCB itself,

I wanted to know if any of these two schemes are correct.
If there needs changes Please Help.

Thanks so much

Since the rectifier is shared, make the big caps shared also. Then make C7 and C8 smaller. Lets say 1000uF(you must be in the distributed power camp).

 

[ctrlx]

Im finding grounding confusing.

Firstly apparently differing schematics ie post 29 and say D. Self's book sch.

Secondly, how to physically wire things up from the schematic.

So far i put a bolt on the chassis, then i connect everything to it ie mains earth, txmr ov's, filter cap ov's, pcb ov's, speaker ov's...etc.
However schematic to me seem to suggest otherwise...

 

[DF96]

You are combining safety ground and signal ground. Generally a bad idea for audio, and regarded as unsafe by electrical safety codes.

Three things to get grounding right:
1. Regard every ground connection as a resistor - it is a resistor, even though it will be quite a low value.
2. Avoid ground loops wherever possible by making each point which needs to be grounded have one and only one ground connection.
3. Unavoidable ground loops should have as small an area as possible, perhaps by twisting together wires carrying opposite currents.

Perhaps I should add a fourth rule:
4. Don't blindly follow any grounding rules!

 

[ctrlx]

You are combining safety ground and signal ground. Generally a bad idea for audio

OK, give me a sketch of how you do it.

Lets do a dual rail psu i.e. twin secondary txmr, 1 bridge rect, 2 filter caps, 2 power amp boards with high and low current 0v's and 2 input/output connectors.