Some plug in EQ's cause phase shift while others don't. It depends on the type. You would probably get the best info on this from the designers of the respective plug ins ...

Many EQs cause phase shifting because the plugins are digital versions of analog EQs. Both is based on mathematical aproximations that cause phase shifting. But EQs with linear phase shifting sound better if you don't wanna hear any special character of some EQ that is good just for it's special sound coloring character. Anyway linear phase EQ's have a few times higher cpu usage. Maybe I'm wrong but I think that all EQs have phase shifting. Are there any EQ's based on FFT (fourier transformation) and IFFT(inverse FFT)? Maybe it could be the way to make EQ with no phase shifting, but that means FFT, multiplication of 2 functions and than IFFT every period so it could have very high cpu usage and there have to be some a latency. Anybody knows something more about this?

I remember reading an article in Mix magazine a few years ago about digital EQ that did not introduce any phase component, but honestly don't remember if it was built into a digital console, or was a plugin. I primarily use Waves Renaissance for my plugins.

there will always be some kind of phase shift. Some Just do more than others.
Just put some HPFs at Waves Q10 with a reasonably hot signal and see how nasty it gets..
There is the linear phase approach like Waves Lin Phase Eq and the PSP Master Q.
Check and see if it does fine for you.
In Frequency domain , when evaluating a transfer function F(s), depending on the data processing and manipulation, you can have poles and/or zeroes. They will contribute for your overal phase status;
There is a plot one can build named Bode´s Diagram whewre one can read Gain x Frequency X Phase.

I remember using transfer function analysis in school days to plot the phase angles of an audio system relative to the reactive components at inputs & outputs. Those system-wide phase shifts are chiefly responsible for things sounding great on the monitors where the music is recorded, but like two cans and a string somewhere else!

F(s)

EXACTLY! I can not remember right now, but seems a pure pole add a phase shift of -90º and a pure zero +90º.

Alecio, WOW, what a beautiful place you live in. I sent my wife some webpages from hotels there, it's been a while since I've had any fejuada and aguar dente! :D

jonny, have you ever been to Florianópolis, the Magic Island?
Yes, lots of USa guys have just discovered it.
It is the new Rio de Janeiro/Florida of South America!

Never been to Brazil, hope to go someday. I had some friends from there that lived in the US several years ago, and I sure love the music. There's a radio program every Sunday called the Brazilian Hour tha I listen to often. My favorite artist right now is Sylvia Torres. I'll let you know if I can talk my wife into a long flight (she hates flying).

I have never heard about this singer. Probably she established a career in the USA.
Good to know they are doing fine
:)

She's in Rio, supposed to be a popular back up session singer and just starting to be known as a solo artist. Check her out!