Question about active crossover

[dnv]

I don't understand about the section in red block. What are them? Do they relate to cut off freq. May someone clarify it to me,please.

 

[AndrewT]

filter with a limited frequency range.
Some might call it a shelving filter.

The first part outside the red is difficult to get right.

A single pole filter that is buffered such that Rs= zero and Rload = infinity is a standard filter block.
You show a two stage filter where the Rload of the second stage "loads" the first stage such that Rload << infinity.
And the first stage sources the second stage such that Rs>>0.
This results in the cascaded filters NOT performing as two single pole filters with the correct loading.

 

[dnv]

Thanks. This is from GSI X-1 xover that sold in 70's. Someone said it was one of
the best in that time. That's why I try to figure it out.

 

[phase_accurate]

Depending on the dimensioning this could be either

1.) A simple second order crossover with some driver equalisation

or

2.) A second order symmetrical transient-perfect crossover (i.e. constant voltage crossover)

Regards

Charles