grounding help.

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Carlos,
Consider not only the current from the transformer through the psu capacitors but also the current from the capacitors through the amp output transistors and then through the speaker and back. For the latter you will have two loops: one for +'ve speaker current and one for 've. By using a "spur" between the capacitor ground bus and the star point you will see that these two current loops share the spur. The upshot of this will be that current in one loop will induce a voltage across the spur and this will cause the voltage on the other opposite power rail to be modulated by this current. The impact of this will depend upon the wideband PSRR of the amp and in the worst case will cause distortion and instability. Obviously if the spur is very thick and very short (a few millimetres say) then it doesn't matter too much.

I see no electrical reason to avoid a single star point provided that the current loops are kept parallel (like my bolt method earlier). I also see no reason to avoid connecting the chassis at this point. In fact, I'd say this is the best point to connect the chassis and mains earth. It is important to ensure that the input connectors of the amp are not earthed directly to the chassis at the connectors (otherwise you have two routes back to the star point).

Do you remember the explanation given by those who criticize a single star point? They may have another problem that is leading them to say this.

As for ground planes and wide-area grounds it is important to think carefully. If you can't work out where the current loops are flowing then don't use a ground plane! No need. After all, we are talking about a mix of high and low current circuits here at low frequencies. Ground planes are not intended for this but are usually used to create low impedance RF paths. Don't use a ground plane unless you are clear about why you need it and what the implications are: keep it simple.

BAM
 
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