Or the other way around: if (as the OP said) the first one is a low-pass with -3dB @600Hz, it most likely will be flat @80Hz (and add no phase shift).
Even after this thread I'm still not sure what is meant in this particular case by "cascading" filters. Does that simply mean "put one filter after another"?
I think this was what the OP meant: put them in a series and determine what happens to a full band signal passing through it.
As a side note: Understanding Decibel math is no easy matter
What do you mean by cascade?
WHATEVER it is, the AVR crossover can't affect it positively or negatively as far as I understand it.
The person I was discussing who claimed the passive crossover elements in the speaker still cascade with the receiver crossover, THAT is what I wanted to know. From what I know, this generally can't happen.
I take it to mean "if multiple units are connected in series, will the output be affected by only one component, or all components". The answer is that the output will be affected by all components.
I'm also not entirely sure any more what Yahzi's position is. In the OP he warns that the filters will affect eachother, but later he doesn't believe that they will affect eachother anymore.
I agree that two filters will combine or cascade if operating within the same range.
If a 80 Hz low pass was operating with a 100 Hz low pass then I imagine there would be a phase shift of some kind.
What I disagreed with is the idea that a speaker crossover could be affected by the receivers own crossover, which is what my friend was saying.
So please accept that you were wrong and your friend was right. Can we move on now?
And how do they know if they operate in the same range or not?
Seriously, one more time - they *will* combine in *any* case. That result might not cause an audible difference if their ranges are far enough apart.
In any case, Arnold said that stacking the filters will have undesired consequences, so it appears that Yahzi is right and his friend is wrong, but for the wrong reasons.