Question concerning phase shifting in opamp xover

[taotao]

Hi members,

I put together an active xover based on opamps. It's based on a Sallen/ Key circuit with a slope of 24dB. Also there's a notch arround 30Hz.
I intend to use it with my Apogee Duetta (magnetostatic 2way planar).
The Notch should cure a big panel-resonance in the bass-foil.
When I simulate it in LTSpice I see a phase shift from 0- to 360 degrees.
Like the attached pic.
This puzzles me a bit, 'cause I read that this kind of circuit is phase coharent (?right word?).
In my understandings, ideal phase diagram should be a strait line (theoreticaly).
Can I expect instabilities in reproduction of space (placement of singers, instruments, etc). Or is this shift ignorable?
If yes, are there ways to flatten the phase-shifting?

Thanks for your input.

[Drew Eckhardt]

Originally posted by taotao
Hi members,

I put together an active xover based on opamps. It's based on a Sallen/ Key circuit with a slope of 24dB. Also there's a notch arround 30Hz.
I intend to use it with my Apogee Duetta (magnetostatic 2way planar).
The Notch should cure a big panel-resonance in the bass-foil.
When I simulate it in LTSpice I see a phase shift from 0- to 360 degrees.

The outputs from a fourth order cross-overs sum to a second order all-pass.

This puzzles me a bit, 'cause I read that this kind of circuit is phase coharent (?right word?).

The outputs of a 4th order Linkwitz-Riley cross-over are 360 degrees out of phase at all frequencies.

In my understandings, ideal phase diagram should be a strait line (theoreticaly).
Can I expect instabilities in reproduction of space (placement of singers, instruments, etc). Or is this shift ignorable?

People can't dectect the phase shift of an LR4 cross-over by itself.

First order speakers have measurably different power response and distortion. The mid-range drivers used need to be resonance free as opposed to resonance supressed. Some people probably prefer those characteristics.

If yes, are there ways to flatten the phase-shifting?

DSP although you may get some off-axis pre-ringing.

[taotao]

OK, thank you Drew.