As you know, I was looking at xover freq in 800 hz range, for a two way system. So, my questions are:

Is 12 db/oct rolloffs enough, or should I go for 18 or 24 db/oct?

If I cascade two 12 db/oct filters, the Fx point will be -6 db instead of -3 db. Should I overlap the hi pass and low pass a little more?

I had sent you active filter topologies I had gotten from two different sources... one from a Radio Shack op amp book, where all C = C and all R = R. Values were computed from Fx = 1/(2piRC). The second was the same topology, but values were not equal, and it was described as "Butterworth". I am more the KISS type, and was leaning toward the former equal value circuit.

As op amps, resistors and caps are cheap these days, I am leaning toward 24db/oct. (I remember as a kid paying $1.50 for a diode for a "crystal radio". Oh, I could pick up two stations with mine!)

Suggestions?

http://www.linkwitzlab.com/filters.htm#3

and it is to a page with info on Linkwitz-Reilly filters. This one shows a 24 db/oct two way.

The topology and values are the same as those I sent you from the old Spkr Builder article. The formula is slightly different, but the results end up being the same. For example, in one, caps might me C and C/2, and the other 2C and C, but once you ran all the numbers, the values ended up the same.

For those interested, there is a schematic at that link.

There is a link under the schematic to a plot of the xover.

Also, check out the subsonic filter at the top of that page.