Eliptical xo's

[T edward]

How would I go about designing an eliptical ox? Tom Daugherty

[theChris]

for a simple example, i suggest downloading nuhertz 's "filter free" or such. this will give you an example of a 2nd order elliptic stage.


the main key of the so called "elliptic" filters is the addition of a "stopband zero" to the system function.

the downside is that this adds two zeros to the system function, and thus the final slope will be -0db/oct for a 2nd order block. a third pole can be added to give a slope of maybe -30dB/oct in the region of interest, then a slope of -6dB/oct in the stopband.

its really similar to a bandstop filter, except the stopband is attenuated by a constant.

and of course you can add a 2nd order filter as well.


note that the hourglass design seems similar to some patented designs... you might try basing a design on an hourglass design with a stopband attenuation of -40dB and a cutoff attenuation of -6dB. then maybe add a 1st order network at a higher frequency around 5-10x Fc (for lowpass).

[forr]

An active solution I built and I liked :

The Best Active Crossover - Here!