Out of phase: is this a problem?

[jdifool]

Hi all,

I'm doing some mastering and I've found a very attracting effect, it really expand stereo indeed but the problem is: it's now out of phase. The phase meter goes between -1 and 0 and taps -1 often.

One of the thing I know about recording is: no out of phase. But why? Where is the problem? The important is the mono compatibility isn't?
The tracks are OK in mono. It's to be released on CD, no vynil. So, should I take care of something?

Thanks

[juppu]

hi,

The issues are mono compatibility and stereo field width, really.

Putting things 180 degrees out of phase would theoretically cancel everything that's panned to centre in mono (or if in-phase is left and out-of-phase is right, this will be cancelled as well). Some psycho-acoustic devices and plugins add some out of phase signal and blend it with the original, which means it's not completely off. It could work in mono, it just depends on the program material and the amount of phasing.
Look out for low frequencies, you might lose everything down there if you're not careful.

The other issue, stage width is subjective, but the rule of thumb is not to make things too wide. It distracts the listener and makes the whole thing sound a bit wishy-washy. Putting things out of phase increases the percieved stage width and if it's applied to the whole mix, it can really screw things up and ruin a good mix. I find its best use when you can't fit something in the stereo field, you put it out of phase - say, you got a keyboard, hard pan it, take it to another two tracks, flip the phase and reverse the pan positions, L becomes R and R becomes L out of phase - sounds like it's coming from outside the speakers...

I use phase tricks every now and then, but your ear gets fooled easily to think that it's magic or something, so be very careful.

(If you wanna hear this, check out the piano on www.artistcollaboration.com/users/juppu/OnlyHuman.mp3 (http://www.artistcollaboration.com/users/juppu/OnlyHuman.mp3) - I used the technique above on it)

Was this any help?

Juppu

[jdifool]

Yes, it helped indeed. I was already carefull about low frequencies and I didn't thought about using it on individual sounds.

Cheers

[Matthew Skinner]

If it sound good then it probably ?!?! is ? Use/trust your ears and see what it sounds like in mono and stereo.

Phase has been used as an effect for a long time...

CHORUS
PHASER
FLANGER

they all play with the phase of a signal to give a stero effect.

[Matthew Skinner]

If it sound good then it probably ?!?! is ? Use/trust your ears and see what it sounds like in mono and stereo.

Phase has been used as an effect for a long time...

CHORUS
PHASER
FLANGER

they all play with the phase of a signal to give a stero effect.

Dont ever get stuck in the thinking, "that shouldn't be done" experiment and trust your ears.

[jdifool]

All right.

Some of my tracks are slightly flangering when I check mono compatibily. But anyway, who does still use mono nowadays?

I know that it can ve a problem to press vynil, is it?

Cheers

[Matthew Skinner]

Television, most TV's would be in mono. Clock radios are mono mostly, AM radio is another which most people listen to in mono, the list goes on...

Its all about making the song sound its best on ALL systems for everyone, thats what a mastering engineer has to correct amoung many other things. In fact a good engineer will listen in mono on near feilds for 60- 80% of the time he is working on a song !

[macouno]

matthew is correct.

if you create something to go out to tv/radio stations it should be mono compatible. There's a lot of people listening on car stereos that are still mono and mono tv sets too.. oh and alarm clock radio thingys.

Also a radio broadcast is not broadcast in regular stereo but joint stereo.

Thing about this is that it doesn't send left/right signals. it sends the mono signal as one channel and the other channel is the difference between left and right. why?

Ok well people listened on old mono radios to the radio... then we suddenly all wanted two channels but didn't want people on old systems to only hear the left or the right channel. Thus we still send out the mono thing. We could have started sending out 3 channels but that would have been inefficient.

Thus all radio receivers now receive joint stereo. internally they take the mono and add the difference for right and subtract it to get the left, sorta basicly if I understand it.


What has joint stereo got to do with phase you ask? well quite simply from experiance I can say that if something is really extremely out of phase... that also degrades the audio signal in the conversion.

Simply put... for broadcast it is a good idea to keep things mono compatible. For other purposes... whatever works for you.

[bdreams]

To add to this 5.1 surrond sound uses
out of phase for the rear speakers so
if the whole signal is 180 deg out then
you'd hear it only on the back speakers.

[Sheriton]

Originally posted by bdreams:
To add to this 5.1 surrond sound uses
out of phase for the rear speakers so
if the whole signal is 180 deg out then
you'd hear it only on the back speakers.



Actually, it's Dolby pro logic that does that. 5.1 sound uses 6 discrete channels to store the sound, there's no matrixing going on like with pro logic.
Sheriton