Doepfer

Hello,

I'm a total novice on circuits and circuit diagrams, so I have a very
basic question.  On the A100 DIY page, what does the ground symbol
mean exactly?  I'm a little confused because this diagram on wikipedia
shows no ground connection for an RC filter:
http://en.wikipedia.org/wiki/RC_filter.  Does it just signify which
side of the jack to connect to?  Or does it make the filter work
better than the version on wikipedia?  I'd like to avoid having to
connect a passive circuit to the power board.

Thanks,
Monroe