stereo expander: don't use, even when it sounds fine (both mono & stereo)

[Marbarbaar]

Hi,

At a friend's DAW I tried out the Sonalksis 'stereotool'.
While normally avoiding stereo-expanders, this one gave some nice sounding results on my musicscore.

PAZ analyzer shows immense anti-phase, but when summed to mono the track basically sounds 99% the same, whether with or without the stereotool.


So there are phase problems, but you can't hear them...?


What do you think I should I do? Should I use this tool? Could I expect problems somwhere down the pipeline, even though it sounds fine in mono?

Is it safe...?


Thanks!!

[Beyersound]

Originally Posted by Marbarbaar

Hi,

At a friend's DAW I tried out the Sonalksis 'stereotool'.
While normally avoiding stereo-expanders, this one gave some nice sounding results on my musicscore.

PAZ analyzer shows immense anti-phase, but when summed to mono the track basically sounds 99% the same, whether with or without the stereotool.


So there are phase problems, but you can't hear them...?


What do you think I should I do? Should I use this tool? Could I expect problems somwhere down the pipeline, even though it sounds fine in mono?

Is it safe...?


Thanks!!

As many others have said: "If it sounds right it is right"!

[jahtao]

QC might raise an eyebrow at the meters but they'll check it in the same you have... and come to the same conclusion you have.

Matt

[DrDeltaM]

Originally Posted by Marbarbaar

PAZ analyzer shows immense anti-phase, but when summed to mono the track basically sounds 99% the same, whether with or without the stereotool.

That's the thing that matters, a good stereotool makes the mix still sound good in mono

[soundboy]

I once had to re-lay 13 episodes of a series because of a stereo expander used on the music track. You give too much credit to QC departments. If the phase is off, it gets kicked back. Don't use it.

[Marbarbaar]

Originally Posted by soundboy

I once had to re-lay 13 episodes of a series because of a stereo expander used on the music track. You give too much credit to QC departments. If the phase is off, it gets kicked back. Don't use it.

So it's often (/always) kicked back in such cases?

The soundtrack of this animation I'm working on for is not for t.v. broadcasting, but nevertheless, I would like to score for t.v. , that's indeed why I asked this question.

thx!

[philper]

Originally Posted by Marbarbaar

So it's often (/always) kicked back in such cases?

The soundtrack of this animation I'm working on for is not for t.v. broadcasting, but nevertheless, I would like to score for t.v. , that's indeed why I asked this question.

thx!

Well--how much expanding do you want to do? How much out of phase material is present in the audio already? Do you have a phase meter that can show you the phase condition of that pair? I've done a lot of subtle widening of stock/needle drop music especially, to get it out of the way of dialog and have had no problems with it w/ QC, but would suggest you proceed on a case-by-case basis while checking the file in mono (at least). A phase meter of some sort is a good idea.

Philip Perkins

[Henchman]

Did you see what happens when encoded for Dolby?
I stay away from pseudo wideneres because I don't want to run into weird problems.
I mixed a movie last year, and one of the music tracks had been treated by soem kind fo widening plug-in. Which resulted in the opening-guitars completely disapearing when run through the encode/decode process.
I had to do some fancy editing on the stereo music to cretae a useable intro for that cue.

[marcanthony]

i used a stereo expander on a stereo music track as part of a TV spot.

it all sounded and looked fine.

it even sounded great on a standard TV but when the composer heard it on his surround set-up at home, all the music for some reason was pushed to the surrounds. the only thing different to over 20 spots we had mixed together was the stereo expander.

can't be sure what happened but for me, the risk is not worth what extra you might think you gain.

[philper]

Originally Posted by Henchman

Did you see what happens when encoded for Dolby?
I stay away from pseudo wideneres because I don't want to run into weird problems.
I mixed a movie last year, and one of the music tracks had been treated by soem kind fo widening plug-in. Which resulted in the opening-guitars completely disapearing when run through the encode/decode process.
I had to do some fancy editing on the stereo music to cretae a useable intro for that cue.

Yes. It was all fine. But that is/was because I was careful not to try to "open up" music that might have been mixed too wide already. In TV docs I get a mix of stock music (very centered stereo usually, can stand some widening), well-composed and recorded score (generally good to go as-is) and some oddball cues that might have been from albums, which actually might need the opposite treatment--pulling them in somewhat. In all these cases having a phase meter or display available all the time is very helpful.

Philip Perkins

[iegido]

Vaz Analyzer meter shows soundfield width that may look phase inverted when it´s just out of phase, or uncorrelated.
Having 2 signals uncorrelated doesn´t mean that mono addition of them will make you loss it all. For stereo mix checking I recommend simple correlation meters. They won´t show how wide your mix is, but will show when the mix tracks go phase inverted. Led bargraph or vu-meter style they will work fine in most cases. As you may know range goes from -1 to 1.

Again, having a "0" value in this kind of correlation meter doesn´t necessarily mean signal cancellation. It means signal in the each channel is different enough that there is no relation between them. When they go phase inverted, meter will go fast to "-1". It is usual to get values near above "0" in the instrumental part of a song between vocal verses.

If your mix sound OK in mono it may be jus uncorrelated.

When mixing fot TV be careful even with high correlated (narrow) stereo mixes because some TV stations will take just the LEFT track of the mix when they say mono, instead of downmixing. If you left something only in the RIGHT track it may not be heard.


Dolby Prologic uses a phase shift circuit in order to "encode" 4 channels using a stereo pair. When listening this pair without a decoder, Surround Channel will appear phase inverted in L an R speakers so it will (should) result cancelled. So the signal wich feeds the "surround" input of the encoder will be phase inverted in L and R. This way compatibility between prologic and stereo users is made.