EQ and phase problems

  • Thread starter Thread starter fendorst
  • Start date Start date
F

fendorst

New member
I understand that cranking up a different EQ setting on every individual track in a mix can lead to phase issues, smearing etc.

Do you still get phase problems/smearing if you print each EQ'd track to a new track and then mix the new tracks?

After printing EQ to each track you'd be mixing a bunch of tracks to which you would not add any EQ. Since you're mixing tracks without adding any EQ, are the phase problems avoided?

I'm not recommending the above. I already know the best answer is "If you have to add significant EQ to every track you're doing something wrong during tracking."

It's just a philosophical or technical question. If you print EQ to each individual track and then mix the new tracks without adding any more EQ, do phase problems and smearing go away?

Discuss.
 
The printed tracks would still have the phase shift from the eq on them.
 
fendorst said:
It's just a philosophical or technical question. If you print EQ to each individual track and then mix the new tracks without adding any more EQ, do phase problems and smearing go away?
Click to expand...

No, printing the track to a new file will not remove the phase changes.

Phase shift causes eq, not the other way around. The only way to avoid it is to use a linear phase eq, which has its own drawbacks.

Unless you mix two copies of the same audio with different eq settings the phase changes should have little audible effect.

In other words, there are lots of far more important things to worry about than phase shift from eq.
 
fendorst said:
I understand that cranking up a different EQ setting on every individual track in a mix can lead to phase issues, smearing etc.
Click to expand...
This part is not correct setting EQ on every track dose not bring about phase issues
 
jaynm26 said:
This part is not correct setting EQ on every track dose not bring about phase issues
Click to expand...

"Issues" is a rather subjective term. Minimum phase type filters always cause phase shift when used.
 
bouldersoundguy said:
In other words, there are lots of far more important things to worry about than phase shift from eq.
Click to expand...

Absolutely.

If it sounds better when you apply some EQ (boost/cut)...don't get too hung up about phase "issues".
 
jaynm26 said:
This part is not correct setting EQ on every track dose not bring about phase issues
Click to expand...

Great feedback so far, thanks to all. So what does bring about phase issue, or what is the smearing audio guys talk about? I try to use as little eq as possible by thinking ahead during tracking to get a good useable sound. I always thought i was preventing phase issues and smearing that can be caused by throwing too much eq on every individual track.
 
Hmmm...this has got me thinking. Every hardware EQ box I know introduces phase variances (even the really premium ones) but I wonder about "in the box" EQ. I'm going to have to do some experiments next time I have a spare hour or two.

In any case, don't get hung up by the idea that EQ introduces phase shifts. Yes, it tends to but it's rarely bad enough to be particularly audible and certainly shouldn't be a problem. Everything you ever listen to has phase differences, if only because your ears are 8 inches or so apart--indeed, without phase differences there'd be no stereo image and you'd never be able to tell what direction a sound is coming from. No, phase errors from EQ aren't quite the same thing--but they're far from a disaster or even a problem.
 
Bobbsy said:
Hmmm...this has got me thinking. Every hardware EQ box I know introduces phase variances (even the really premium ones) but I wonder about "in the box" EQ. I'm going to have to do some experiments next time I have a spare hour or two.
Click to expand...

Hey Bobbsy, just cause I'm a question asker, what kind of tests could you do, and how would you tell how bad the phasing is?

I heard Dave Pensado say something like "I can tell you only used on mic because I can't hear any phase" when asking about micing an acoustic guitar. I understand phase relationships, but I am terrible at hearing them except with a typical 180 degree flip of a snare over/under or a front/back guitar cab situation.

I like to zoom in on my OH drum tracks and see if they line up, and then move them so they do to see if it sounds better and then A/B to hear the change. I understand why having them lined up sounds better, but spotting it without seeing the tracks and doing my A/B seems like a long shot for me.

I'm sure more experience and time will help, but what are you hearing in a situation like with 2 mics on a source, or with slightly misaligned Overheads?

Sorry if I took this away from EQ a bit, but it's all related...
 
Well, I haven't thought it through completely but I have software that gives me a phase analysis function (most trippy display you'll ever see!) and I was thinking in terms of recording a test signal, applying EQ through an outboard unit and comparing the phase on the original and EQ'd signals. Then do the same thing with in the box EX. (My mental question was that, with an external analogue EQ, a phase shift is inevitable because of the way the EQ works--but this might not apply to EQ in the purely digital domain.) Anyhow, today is a bit busy (family outing) but maybe I'll play in the next few days.

It's hard to describe what you hear when listening for phase differences. At the most benign, if you hear a stereo image and can detect different things at different places (or even moving in the field) that's down to phase differences.

At the "problem" side of things, you might hear unpleasant "phasey" effects or things like comb filtering where some frequencies are emphasised and others attenuated. It's hard to describe--it's one of those "I'll know it when I hear it" things.
 
The phase shift everyone talks about isn't an interaction with other tracks in the mix, it is introduction of phase cancellation to the track that you are eqing. But that's how eq works. That's also why, when you cut frequencies, you end up boosting the frequencies around the corner points.

When one eq sounds different than another one, it is because of the way it implements the phase cancellation to do its job.

It's really not something to worry about. If you eq something and it sounds better, leave it alone and get on with your life.

Phase is not always a bad thing. It is one of the cues that allows us to locate a sound that we hear. People will sometimes use two miss on a guitar amp, one pointed right at the speaker, the other at a 45 degree angle to it. They are using the phase difference between the mics to get the sound they are looking for, like eq.

Remember, if it sounds good, it is good. It doesn't matter how you got the sound as long as it works in context. All this hand wringing about phase issues is kind of silly.
 
fendorst said:
I always thought i was preventing phase issues and smearing that can be caused by throwing too much eq on every individual track.
Click to expand...

You already got good answers, especially the main point that phase shift is just how EQ works, and that there's nothing wrong with it. I'll add my theory about why you sometimes read people claiming that EQ adds a "phase" sound quality:

The Audio Expert said:
Again, while phase shift is the cause of the response change, it's the response change that you hear and not the phase shift itself. Indeed, some people claim they can hear phase shift in equalizers because when they boost the treble, they hear a sound reminiscent of phaser effects units. So they wrongly assume what they hear is the damaging phase shift everyone talks about. In truth, what they''re really hearing is high-frequency comb filtering that was already present in the recording, but not loud enough to be noticed.

For example, when a microphone is placed near a reflective boundary such as the wooden lid of a grand piano, the delay between the direct and reflected sounds creates a comb filter acoustically in the air that the microphone picks up. If the treble is then boosted with EQ, the comb filtering already present becomes more apparent. So the equalizer did not add the comb filtered sound, but merely brought it out. The "problems" caused by phase shift have been repeated so many times by magazine writers and audio salespeople that it's now commonly accepted, even though there's not a shred of truth to it.
Click to expand...

--Ethan
 
sixer2007 said:
... I heard Dave Pensado say something like "I can tell you only used on mic because I can't hear any phase" when asking about micing an acoustic guitar. I understand phase relationships, but I am terrible at hearing them except with a typical 180 degree flip of a snare over/under or a front/back guitar cab situation.

I like to zoom in on my OH drum tracks and see if they line up, and then move them so they do to see if it sounds better and then A/B to hear the change. I understand why having them lined up sounds better, but spotting it without seeing the tracks and doing my A/B seems like a long shot for me. ..
Click to expand...
A few basics to try out--
First is you've heard the phase effect -on 'guitar pedals, 'flangers etc. It's the comb filtering of frequencies canceling and adding when combining the same thing out of time by different amounts. Their relative levels in their mix is the depth control of the effect, the strongest being at a 50/50 mix of the two.
As the time difference increases past zero' the frequencies that begin to be effected go lower.

A very easy experiment- Take two mics, some headphones and a nice steady full range sound. Start with them both right at the speaker. Slowly pull one back and forth.
'A few inches, you get phasing only in the top few octaves.
Out around several inches the top few still phasing' but now the mid range is as well, etc.

So, part of this is; If there is a time difference there, these phase differences are going on.
If you'd like to hear them better (to get a clearer view of a situation or what ever), bring them up to equal level (and in mono.
Very often in the mix of things these effect can be going along just fine, maybe adding some of their tone effect in their less than full strength combinations.
 
Funny that this came up here... I just posted this vid on my facebook page like three days ago. Its a very clear and concise explanation of Linear-phase and Minimum-phase EQ by FabFilter. Definitely worth watching. It goes without saying that you should make sure you use headphones or proper speakers.

 
+1 Jay Walsh!

apparently I "must spread some Reputation around before giving it to Farview again."
He talks too much sense.
 
You must log in or register to reply here.
Back
Top