Re: gEDA-user: pcb via and ground planes

[gene glick <carzrgr8@xxxxxxxxxxxxx>]

> 
> Perhaps if you explained *why* you're using a trace that way, we could
> help you figure out how PCB would prefer to handle that situation.


I figured that question was coming next :)

Those particular traces you see are low frequency audio.  There's 
several channels of it.  In order to reduce cross talk, it's necessary 
to force the current to go where you would like it to - this includes 
the return line, aka ground.  Due to the low frequency nature of audio, 
for all practical purposes, DC, the return signal is going to flow in 
the shortest physical path back to the source.  This open up the 
possibility of cross talk when the currents from more than one channel 
share the same path.  (this is all much different than high frequency 
stuff that follow the path of least inductance)

Maybe a better way to say it is, each audio signal and it's return 
should be treated as 2 conductors, separate from the others.  The only 
difference is that all the grounds eventually connect together somewhere 
insignificant.

This requires that the ground *not* be a solid plane (at least not in 
this section of the board).  I thought it would be easier to route a 
trace than place rectangles or polygons.





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