Much better layout! Your red circle denotes your power supply star point. Now
comes the complicated part. Your input/output grounds should go back to the star
point. This sometines is inconvenient especially when one may use an external
power supply or if you are feeding multiple audio circuits. What then??? Looking
back at my previous post, I mentioned that you place you bypass and filter caps
across the opamp supply, to a common point ground, and then back to the star
point. This common point ground becomes your audio star point. Confusing? Yes, a
little, but as long as your power supply is not feeding any other circuits, this
becomes your actual star point ground, and all input/output grounds MUST return
to this point. It also makes it a little easier to lay out the circuit board by
connecting to this new point.

The +/- traces can run almost anywhere but.......when it gets to your
application circuit, you must bypass
cap it at that point, to your star point. Laying out a board is just as
important as designing the circuit. You may want to clip that sentence out,
print it in large fonts, and tape it to your display monitor :-) I've spent 30
years laying out over 3000 different boards, some that are in most audio
broadcast consoles (mixers) throughout the world. I've learned that improper
grounding techniques can literally destroy an audio product.

You're on the right track though. Good luck.
Rick

Tal Bejerano - AMC wrote:

> OK! if I got it right it should be like the attached pcb sample ? (the red
> circle) just draw this section, the other ideas are understood.
> this the famous star point? it sure make pcb editing very hard to do!
> especially if I don't have large room.
> what about the  + - traces? is it important also? should I take any other
> steps? or just this ground stuff is important?
> what about the ground for the input outputs jacks of the preamp? should it
> go to this star point or I can connect it to any other ground point?
>
> Whatever.. I miss my vinyl records :-) it worth it....
>
> Regards

<snip>

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