Understanding AC line filters better

[pjpoes]

Ok so please bare with me here, I'm not an engineer by trade and am mostly self taught, so if any of this is wrong, I'm here to learn. I want to better understand the designing of AC line filters, and how values are chose for each of the components. I understand the role of a Varistor, the good and bad, and how values are chosen for that. It's the actual crossover or filter part.

Using John Risch's AC schematic we see what looks to me like essentially a 3rd order filter. However, because we are dealing with H, N, and G, it isn't something I can make analogous to a speaker crossover. However, I have a better understanding of those, so if someone wants to describe it in those terms, that would be best. We have a CLC filter basically, and I imagine that, based on the impedance of the load, the frequency it cuts off at will change. First question, how are values chosen here, and how crucial are the inductors and capacitors values?

Is there a way to use a simple crossover software to model the frequency of the ac filter? I mean, they both are modulated signals in a way. One is an intentionally modulated signal at various frequencies to make up the musical signal, the other is modulated at a fixed 60hz (u.s. market) for long distance transmission of energy. The goal, I imagine, is to create a low pass filter which removes any RF noise which has entered the line, and would be considerably higher than 60hz, probably in the mhz range. A filter capable of crossing over or filtering much lower and with a steeper slope is preferred I would guess, no? Could I take a crossover software, input the measured impedance of my equipment with not powered up (I know that isn't an accurate impedance), enter that as a ZMA file, and then model a 3rd order crossover to figure out where my values are crossing it over.

Another thing, in the Risch design, he has one basic filter for the whole system. You could, of course, use multiple filters for each outlet, but as a more economical version, could you use a separate capacitor at each outlet for the C4 position. I have a bag of Siemens mylar X2 caps rated for 250vac and .33uf's. I was thinking of putting the .33uf's across the back of each outlet from H to N.

Oh, I think I'm going to know the answer to this in the end, but I will ask it anyway. What is a T-filter or T-network. Tributaries and others talk about having T-networks in their's, and while I think I know, I would appreciate someone else telling me, with schematic if possible.