[sdiy] RC filter questions + SPICE RC filter simulation questions

[cheater cheater]

Hi guys,
I have been playing around with pspice today, simulating and analyzing
some very simple circuits.

I analyzed a simple RC filter: AC voltage source goes through R=1kR
and C=1uF to ground. I analyzed it and got the familiar curve.

Then I stuck some more stages like that on it: there's a series of
four 1kR resistors and after each one there's a 1uF cap to ground. I
analyzed it and got the expected curve at the last stage, but the
first stage has a distinctive bump. Additionally the cutoffs of all
the stages are much lower. Where does the bump come from? Is there a
specific law that defines this?

I am trying to find a way to filter a .wav through the filter and look
at the voltage output. Is this possible to do in pspice? If not, do
any other spice packages allow that?

Thanks
D.