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would this phase correction idea work?

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Anonymous
January 11, 2005 1:49:11 AM

Archived from groups: rec.audio.pro (More info?)

hello everyone,

let's say you 2-miked an instrument and recorded it as a stereo file
into the DAW. then when you listened back, you thought it sounded out
of phase.

would it make sense to simply de-couple the stereo file in a wave
editor and then nudge one of the left or right tracks a few samples to
get it in phase?
Anonymous
January 11, 2005 1:59:48 AM

Archived from groups: rec.audio.pro (More info?)

an easier route would be to usa a program like audition or pro tools or
anything and use a phase canceler/converter/changer/whatever plugin to
adjust the phase and just move the slider a little and listen. i would
personally use the phase analysis tool in audition as it will tell you
to an extreme degree of accuracy wether the tracks are in phase or not.
they may also be 180 degrees out of phase as thworing may have been
mixed up somewhere alon your signal path. try inverting one of the
tracks to see what happens. i would not try to manually change the
phase as your soundcard is probably not good enough to be sample
accurate and differentiate the differance if a sound file is ten
samples delayed or something, did that make sense? whatever. give it a
shot.
Anonymous
January 11, 2005 2:01:44 AM

Archived from groups: rec.audio.pro (More info?)

something i forgot to soay is that if you 'nudge' the file at all you
will be adding delay to the track introducing a possible flanger type
effect, ugly.
Related resources
Anonymous
January 11, 2005 2:26:52 AM

Archived from groups: rec.audio.pro (More info?)

No ! The result will not be mono compatible.
And it will only work if the sound is one single frequency.
There is a difference between electrical phase and
temporal (time, for you earthlings) displacement.
If the 'phase' problem was created by latency then
yes - you correct the difference by slipping one file
to line up with the other. If the problem is one side
electrically "out of phase" then the entire right (or left)
channel needs inverted (polarity) but not slipped in the
time domain.

rd
Anonymous
January 11, 2005 4:02:07 AM

Archived from groups: rec.audio.pro (More info?)

genericaudioperson@hotmail.com wrote:

> hello everyone,
>
> let's say you 2-miked an instrument and recorded it as a stereo file
> into the DAW. then when you listened back, you thought it sounded
> out of phase.
>
> would it make sense to simply de-couple the stereo file in a wave
> editor and then nudge one of the left or right tracks a few samples
> to get it in phase?




Try it. If you miked it at different distances it may make a big
difference; if you miked it in different places, it may or may not help.
Try it. Three samples (at 44.1) will be almost an inch of virtual mic
movement, sort of.

Try it.
Anonymous
January 11, 2005 6:29:01 AM

Archived from groups: rec.audio.pro (More info?)

Takeshi Yamashita wrote:
> Assuming that the temporal delay was entirely due to distance from
the
> speaker in question, why would this not be the exact same thing as
> latency?
>
> tak
>

If the 'phase' issue is due to time delay from differing
distance, then the effect is similar to that of latency.
But slipping the 2 back into phase with each other will
create it's own effect.
Are the 2 signals both centered and at the same level ?
Better to lower the level of the secondary (delayed)
signal until the phase effect is reduced, or better yet:
Center or near center the first arriving signal, and hard
or far pan the secondary signal.
Hendrix used this effect and I like his work.

The question is what's causing the phasing sound
latency/time issues or electrical polarity ?
And is it objectionable ?

rd
Anonymous
January 11, 2005 7:22:06 AM

Archived from groups: rec.audio.pro (More info?)

Assuming that the temporal delay was entirely due to distance from the
speaker in question, why would this not be the exact same thing as
latency?

tak

On 2005-01-11 02:26:52 -0500, "RD Jones" <annonn@juno.com> said:

> No ! The result will not be mono compatible.
> And it will only work if the sound is one single frequency.
> There is a difference between electrical phase and
> temporal (time, for you earthlings) displacement.
> If the 'phase' problem was created by latency then
> yes - you correct the difference by slipping one file
> to line up with the other. If the problem is one side
> electrically "out of phase" then the entire right (or left)
> channel needs inverted (polarity) but not slipped in the
> time domain.
>
> rd
Anonymous
January 11, 2005 8:17:27 AM

Archived from groups: rec.audio.pro (More info?)

Well, the problem is if you "just invert the phase of either of the
channels" and then listened back in mono, the channels would cancel
each other out and you would end up with a very thin sound. If you're
listening back to the track in the context of the whole mix, it will
probably sound like it just dissappeared!

If you can re-record it, that's the better alternative. If you can't,
then try any of the suggestions you've gotten here and make sure you go
back and forth between mono and stereo to see how the sound changes.
You should always do a stereo/mono comparison flipping back and forth
when recording any stereo track .

If you are going to re-record it, there's an easy way to make the mics
more in phase with each other - While positioning the mics, flip one
side out of phase, listen in mono, start with no EQ or effects on
either and get a good solid sound with your first mic. Then with the
second mic, find the position where the sound cancels the most or
sounds the thinnest. The closer you are micing, the more pronounced the
effect will be. Then ,flip the out of phase side back into phase and do
your mono/stereo comparison. This also works better if the mics are
closely matched.

This technique also works great when recording bass using a mic and a
direct box. Start with the direct sound and then, starting about an
inch away from the speaker, move the out of phase mic away from the
speaker until the sound almost completely cancels and then flip it back
into phase. This will get you the strongest signal. Since bass is
almost always in mono it can mean the difference between a solid or a
weak bass sound - and of course - a weak bass sound means a weak mix!
Anonymous
January 11, 2005 8:25:12 AM

Archived from groups: rec.audio.pro (More info?)

Well, the problem is if you "just invert the phase of either of the
channels" and then listened back in mono, the channels would cancel
each other out and you would end up with a very thin sound. If you're
listening back to the track in the context of the whole mix, it will
probably sound like it just dissappeared!

If you can re-record it, that's the better alternative. If you can't,
then try any of the suggestions you've gotten here and make sure you go
back and forth between mono and stereo to see how the sound changes.
You should always do a stereo/mono comparison flipping back and forth
when recording any stereo track .

If you are going to re-record it, there's an easy way to make the mics
more in phase with each other - While positioning the mics, flip one
side out of phase, listen in mono, start with no EQ or effects on
either and get a good solid sound with your first mic. Then with the
second mic, find the position where the sound cancels the most or
sounds the thinnest. The closer you are micing, the more pronounced the
effect will be. Then ,flip the out of phase side back into phase and do
your mono/stereo comparison. This also works better if the mics are
closely matched.

This technique also works great when recording bass using a mic and a
direct box. Start with the direct sound and then, starting about an
inch away from the speaker, move the out of phase mic away from the
speaker until the sound almost completely cancels and then flip it back
into phase. This will get you the strongest signal. Since bass is
almost always in mono it can mean the difference between a solid or a
weak bass sound - and of course - a weak bass sound means a weak mix!
Anonymous
January 11, 2005 8:31:36 AM

Archived from groups: rec.audio.pro (More info?)

If it sounds "out of phase," the error is a heck of a lot greater than nudging
one channel a few samples can fix.

Are the mics the same model? Are they the same distance from the instrument? Is
there a possibility of polarity inversion somewhere in the chain?
Anonymous
January 11, 2005 8:52:11 AM

Archived from groups: rec.audio.pro (More info?)

One more thing you might try that hasn't been suggested yet - Just use
the one side you like best and send it through a stereo plug-in or
reamp it out to an amp and mic it. And of course, as always, do the
mono/stereo comparison to check the integrity of your signal.
Anonymous
January 11, 2005 10:08:50 AM

Archived from groups: rec.audio.pro (More info?)

<genericaudioperson@hotmail.com> wrote in message
news:1105426151.424457.62300@c13g2000cwb.googlegroups.com
> hello everyone,
>
> let's say you 2-miked an instrument and recorded it as a stereo file
> into the DAW. then when you listened back, you thought it sounded out
> of phase.

> would it make sense to simply de-couple the stereo file in a wave
> editor and then nudge one of the left or right tracks a few samples to
> get it in phase?

No, you'd just invert the phase of either of the channels.
Anonymous
January 11, 2005 10:35:14 AM

Archived from groups: rec.audio.pro (More info?)

A "flanger" effect would be a delay but a varying length of delay, i.e.
an "out of phase" pair of signals that change their phase relationship
over time.

Unfortunately, what arrived at the two microphones is a complex picture
of the instrument, and moving the two mics in a time relationship to
each other will not likely fix the problem. However, subjectively, the
sound may improve, although I doubt it.

It may be the case, as someone else pointed out, that simply changing
the polarity of one of the mics may make the most improvement (if one
of the mics was out of polarity in the first place).

Phase and group delay are not necessarily interchangeable...
Karl Winkler
Lectrosonics, Inc.
http://www.lectrosonics.com
Anonymous
January 11, 2005 1:24:17 PM

Archived from groups: rec.audio.pro (More info?)

<b.lessard@comcast.net> wrote in message
news:1105449447.720212.305350@f14g2000cwb.googlegroups.com
]
> Well, the problem is if you "just invert the phase of either of the
> channels" and then listened back in mono, the channels would cancel
> each other out and you would end up with a very thin sound. If you're
> listening back to the track in the context of the whole mix, it will
> probably sound like it just dissappeared!

I'm keying off the OP, which said

"let's say you 2-miked an instrument and recorded it as a stereo file
into the DAW. then when you listened back, you thought it sounded out
of phase."

I'm presuming that somehow polarity got flipped during the recording
process.

That's what the post says to me.
Anonymous
January 11, 2005 1:49:55 PM

Archived from groups: rec.audio.pro (More info?)

On Tue, 11 Jan 2005 01:49:11 -0500, genericaudioperson@hotmail.com wrote
(in article <1105426151.424457.62300@c13g2000cwb.googlegroups.com>):

> hello everyone,
>
> let's say you 2-miked an instrument and recorded it as a stereo file
> into the DAW. then when you listened back, you thought it sounded out
> of phase.
>
> would it make sense to simply de-couple the stereo file in a wave
> editor and then nudge one of the left or right tracks a few samples to
> get it in phase?
>

absolutely.

Ty Ford



-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com
Anonymous
January 11, 2005 2:33:32 PM

Archived from groups: rec.audio.pro (More info?)

>would it make sense to simply de-couple the stereo file in a wave
>editor and then nudge one of the left or right tracks a few samples to
>get it in phase?

Yes, you can do that. Or alternatively you could try one of the
allpass filters available in a plugin form.

http://www.voxengo.com/pha979/

Mark
"In this business egos can be wonderful, but they also can be a curse."
Michael Wagener
Anonymous
January 11, 2005 2:34:13 PM

Archived from groups: rec.audio.pro (More info?)

>No ! The result will not be mono compatible.

Don't ya just love Usenet. <bg>

Mark
"In this business egos can be wonderful, but they also can be a curse."
Michael Wagener
Anonymous
January 11, 2005 2:34:52 PM

Archived from groups: rec.audio.pro (More info?)

"Ty Ford" <tyreeford@comcast.net> wrote in message
news:jsGdnS7uRJI-aH7cRVn-1Q@comcast.com
> On Tue, 11 Jan 2005 01:49:11 -0500, genericaudioperson@hotmail.com
> wrote (in article
> <1105426151.424457.62300@c13g2000cwb.googlegroups.com>):
>
>> hello everyone,
>>
>> let's say you 2-miked an instrument and recorded it as a stereo file
>> into the DAW. then when you listened back, you thought it sounded
>> out of phase.
>>
>> would it make sense to simply de-couple the stereo file in a wave
>> editor and then nudge one of the left or right tracks a few samples
>> to get it in phase?
>>
>
> absolutely.

I don't think so. If you want to de-couple tracks enough to make a
difference, you need to nudge them many milliseconds. You want them to be
far enough apart so that they sound different from each other, but not far
enough to create an audible echo.
Anonymous
January 11, 2005 2:41:54 PM

Archived from groups: rec.audio.pro (More info?)

In article <1105426904.522464.106780@f14g2000cwb.googlegroups.com> sjwatt@gmail.com writes:

> something i forgot to soay is that if you 'nudge' the file at all you
> will be adding delay to the track introducing a possible flanger type
> effect, ugly.

This may be the sort of thing the original poster was hearing when he
said "sounds out of phase." But he should have noticed it when he was
recording.

If the situation is indeed that there was sufficient time difference
between the two mics on the guitar, then moving one channel relative
to the other would be a way to change (and hopefully correct) this.
But one reason why we use two mics on a guitar is because we want that
slightly-out-of-phase sound when the player moves a bit. It makes the
recording sound less static.

Unless of course we DON'T want that effect.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
January 11, 2005 4:32:40 PM

Archived from groups: rec.audio.pro (More info?)

On 10 Jan 2005 22:49:11 -0800, genericaudioperson@hotmail.com wrote:

>let's say you 2-miked an instrument and recorded it as a stereo file
>into the DAW. then when you listened back, you thought it sounded out
>of phase.
>
>would it make sense to simply de-couple the stereo file in a wave
>editor and then nudge one of the left or right tracks a few samples to
>get it in phase?

If you suspect one recording channel was wired backwards, you need to
reverse the phase of that channel, not delay it.

If you feel one mic was closer than the other, a simple delay may
help. Look at the waveforms at high magnification and nudge one until
they align.

Maybe you should just discard one channel - you may have a perfectly
good mono recording of this instrument.

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
Anonymous
January 11, 2005 5:27:20 PM

Archived from groups: rec.audio.pro (More info?)

>
>hello everyone,
>
>let's say you 2-miked an instrument and recorded it as a stereo file
>into the DAW. then when you listened back, you thought it sounded out
>of phase.
>
>would it make sense to simply de-couple the stereo file in a wave
>editor and then nudge one of the left or right tracks a few samples to
>get it in phase?
>

Yes, that will work for a PHASE problem.

It will not work on a POLARITY problem.

Phase involves time and polarity does not.

If you have a polarity problem, simply invert one of the files.
Richard H. Kuschel
"I canna change the law of physics."-----Scotty
Anonymous
January 11, 2005 6:04:10 PM

Archived from groups: rec.audio.pro (More info?)

In article <20050111092720.11282.00000034@mb-m10.aol.com> rickpv8945@aol.com writes:

> Yes, that will work for a PHASE problem.
> It will not work on a POLARITY problem.

Hey, he said "sounds out of phase." Most people don't know what "out
of polarity" sounds like.

When you put two mics on a guitar, unless thery're coincident, there
will be a time offset between them, which can indeed sound "out of
phase." If there's a time offset as well as a polarity difference,
they'll still sound "out of phase" only different.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
January 11, 2005 6:58:08 PM

Archived from groups: rec.audio.pro (More info?)

<< would it make sense to simply de-couple the stereo file in a wave
editor and then nudge one of the left or right tracks a few samples to
get it in phase?
>>




Yes. For that reason, I typically record stereo sources to dual mono tracks.
Once I've slipped the tracks until I'm happy I lock them as stereo.


Joe Egan
EMP
Colchester, VT
www.eganmedia.com
Anonymous
January 11, 2005 7:23:43 PM

Archived from groups: rec.audio.pro (More info?)

On 11 Jan 2005 05:17:27 -0800, b.lessard@comcast.net wrote:

>Well, the problem is if you "just invert the phase of either of the
>channels" and then listened back in mono, the channels would cancel
>each other out and you would end up with a very thin sound. If you're
>listening back to the track in the context of the whole mix, it will
>probably sound like it just dissappeared!

But he think's the problem may be due to one mic being out of phase in
the first place.

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
Anonymous
January 11, 2005 7:23:44 PM

Archived from groups: rec.audio.pro (More info?)

Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote:
>On 11 Jan 2005 05:17:27 -0800, b.lessard@comcast.net wrote:
>
>>Well, the problem is if you "just invert the phase of either of the
>>channels" and then listened back in mono, the channels would cancel
>>each other out and you would end up with a very thin sound. If you're
>>listening back to the track in the context of the whole mix, it will
>>probably sound like it just dissappeared!
>
>But he think's the problem may be due to one mic being out of phase in
>the first place.

Then call it "reversed polarity," which is what it is, and not "out of phase"
which is a general phrase that can encompass a whole lot of unrelated things.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
January 11, 2005 7:23:44 PM

Archived from groups: rec.audio.pro (More info?)

In article <bbv7u0licr5se3gn51ps9tdnnou4ogu1ss@4ax.com> l@laurenceDELETEpayne.freeserve.co.uk writes:

> But he think's the problem may be due to one mic being out of phase in
> the first place.

He does? It wasn't clear from the original message. Just because he
said "out of phase" doesn't mean inverted polarity.

--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
January 11, 2005 7:23:45 PM

Archived from groups: rec.audio.pro (More info?)

"Scott Dorsey" <kludge@panix.com> wrote in message
news:cs0umb$3ll$1@panix2.panix.com
> Laurence Payne <l@laurenceDELETEpayne.freeserve.co.uk> wrote:
>> On 11 Jan 2005 05:17:27 -0800, b.lessard@comcast.net wrote:
>>
>>> Well, the problem is if you "just invert the phase of either of the
>>> channels" and then listened back in mono, the channels would cancel
>>> each other out and you would end up with a very thin sound. If
>>> you're listening back to the track in the context of the whole mix,
>>> it will probably sound like it just disappeared!
>>
>> But he think's the problem may be due to one mic being out of phase
>> in the first place.
>
> Then call it "reversed polarity," which is what it is, and not "out
> of phase" which is a general phrase that can encompass a whole lot of
> unrelated things.

I didn't call it "out of phase" which I agree can be vague and can be easy
to misunderstand.

I said "invert the phase" which has a pretty unique meaning in most places.

We all seem to know that the problem I was addressing was polarity.

Furthermore, the meaning of the phrase "invert the phase" was even
correctly deduced by the person who took exception to my suggestion.

So, let's review: I knew what I meant and everybody who read it seems to
know what I meant. Leaves only one question - where's the beef?
Anonymous
January 11, 2005 11:17:51 PM

Archived from groups: rec.audio.pro (More info?)

genericaudioperson@hotmail.com wrote:

> hello everyone,
>
> let's say you 2-miked an instrument and recorded it as a stereo file
> into the DAW. then when you listened back, you thought it sounded out
> of phase.
>
> would it make sense to simply de-couple the stereo file in a wave
> editor and then nudge one of the left or right tracks a few samples to
> get it in phase?

Hmmm, if I hear something odd like that I'd run the file through some
test software to see if there in fact are phase anomalies. Once identified

I'd have a better chance of adjusting things properly. Inverting the
polarity,
then (normalized) mix to mono can also give some clues...
However, the final check (as always) is by ear.


Later...

Ron Capik
--
Anonymous
January 12, 2005 1:44:31 AM

Archived from groups: rec.audio.pro (More info?)

<< I don't think so. If you want to de-couple tracks enough to make a
difference, you need to nudge them many milliseconds.>>

Not at all. A nudge of a millesecond or less can result in a substantial timbre
shift.

Scott Fraser
Anonymous
January 12, 2005 1:44:32 AM

Archived from groups: rec.audio.pro (More info?)

"ScotFraser" <scotfraser@aol.com> wrote in message
news:20050111174431.25777.00000029@mb-m26.aol.com
> << I don't think so. If you want to de-couple tracks enough to make a
> difference, you need to nudge them many milliseconds.>>
>
> Not at all. A nudge of a millesecond or less can result in a
> substantial timbre shift.

Sure, massive comb filter effects. Is that the best way to deal with the
issue?
Anonymous
January 12, 2005 10:31:20 AM

Archived from groups: rec.audio.pro (More info?)

Ron Capik wrote:
> Hmmm, this has me wondering: What phase
> analysis tools are out there in common use?

Soundcraft's small B100 and BVE100 broadcast
mixers have an onboard phase meter.

rd
Anonymous
January 12, 2005 1:38:54 PM

Archived from groups: rec.audio.pro (More info?)

RD Jones <annonn@juno.com> wrote:
>Ron Capik wrote:
>> Hmmm, this has me wondering: What phase
>> analysis tools are out there in common use?
>
>Soundcraft's small B100 and BVE100 broadcast
>mixers have an onboard phase meter.

Yes, and there are a lot of the outboard meters like the Dorrough and
RTW meters that have basic phase metering. I never found these to be
all that useful, though. They don't really tell you anything that mono
summing doesn't tell you, and they aren't any help for getting a sense
of stereo imaging in bad monitoring situations.

An X-Y display like the Tektronix audio monitor is very useful for getting
a sense of stereo imaging when you can't trust your monitors, and it can be
very handy for broadcast and record-cutting work where the sum and difference
channels are asymmetric. But you very seldom see them any longer.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
January 12, 2005 2:10:42 PM

Archived from groups: rec.audio.pro (More info?)

On Tue, 11 Jan 2005 11:34:52 -0500, Arny Krueger wrote
(in article <ea6dnXeNe6i2nXncRVn-qg@comcast.com>):

> "Ty Ford" <tyreeford@comcast.net> wrote in message
> news:jsGdnS7uRJI-aH7cRVn-1Q@comcast.com
>> On Tue, 11 Jan 2005 01:49:11 -0500, genericaudioperson@hotmail.com
>> wrote (in article
>> <1105426151.424457.62300@c13g2000cwb.googlegroups.com>):
>>
>>> hello everyone,
>>>
>>> let's say you 2-miked an instrument and recorded it as a stereo file
>>> into the DAW. then when you listened back, you thought it sounded
>>> out of phase.
>>>
>>> would it make sense to simply de-couple the stereo file in a wave
>>> editor and then nudge one of the left or right tracks a few samples
>>> to get it in phase?
>>>
>>
>> absolutely.
>
> I don't think so. If you want to de-couple tracks enough to make a
> difference, you need to nudge them many milliseconds. You want them to be
> far enough apart so that they sound different from each other, but not far
> enough to create an audible echo.
>

I do it in Pro Tools all the time. It's quite easy to zoom in and align the
wave forms. Correcting for mic distances or azimuth errors is a snap.

Smiles,

Ty Ford





-- Ty Ford's equipment reviews, audio samples, rates and other audiocentric
stuff are at www.tyford.com
Anonymous
January 12, 2005 3:18:40 PM

Archived from groups: rec.audio.pro (More info?)

genericaudioperson@hotmail.com wrote:

> let's say you 2-miked an instrument and recorded it as a
> stereo file into the DAW. then when you listened back,
> you thought it sounded out of phase.

Why should it? - what possible cause is it that you have in mind?

Also: You ask about delay, not about phase. Phase unlinearity is about
different delay time in different frequency ranges, which is why it is
compensated - if relevant, it was relevant for analog tape recording,
but hardly ever done, and it was relevant for example for the Sony PCM
F1, in which context I have heard it cause amazing improvement - with a
circuit called an all pass filter.

> would it make sense to simply de-couple the stereo file
> in a wave editor and then nudge one of the left or right
> tracks a few samples to get it in phase?

Allow me to label that an "advanced stereo modification to be used with
great caution by highly skilled operators". It is possible to slightly
alter the "midline axis" of the sound from a valid stereo mic setup by
doing what you suggest, but that is a very different concept.

I have done it twice: with a chamber music recording of a piano trio
that placed themselves somewhat different from what was assumed in the
mic placement and with a mandolin and guitar ensemble that was
asymmetrically positioned on a bar scene to focus their sound in the
direction of the majority of the audience.

The indication for doing was with both recordings a perceived inbalance
that could not be compensated with a simple level change. This was not
about something that sounded "partially out of phase".

The proper thing to do is generally to position the mic pair correctly,
delaying one channel relative to the other is a potential cause of more
problems than it solves and mono compatibility is certainly a major
worry to consider.


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************
Anonymous
January 12, 2005 3:27:59 PM

Archived from groups: rec.audio.pro (More info?)

Laurence Payne wrote:

> If you feel one mic was closer than the other, a simple delay may
> help. Look at the waveforms at high magnification and nudge one
> until they align.

It is not *that* simple - it would be if it was a recording in a sound
dead room, but it isn't - listening is also required and what is
perceived right may not "look right". Great caution is adviced .....
including listening on several loudspeaker setups.

> CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm


Kind regards

Peter Larsen

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*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************
Anonymous
January 12, 2005 3:32:14 PM

Archived from groups: rec.audio.pro (More info?)

Laurence Payne wrote:

> On 11 Jan 2005 05:17:27 -0800, b.lessard@comcast.net wrote:

> >Well, the problem is if you "just invert the phase of either of the
> >channels" and then listened back in mono, the channels would cancel
> >each other out and you would end up with a very thin sound. If you're
> >listening back to the track in the context of the whole mix, it will
> >probably sound like it just dissappeared!

> But he think's the problem may be due to one mic being out of phase in
> the first place.

In which case the fix is to reverse the polarity of the inversed
channel, it can not be addressed in any other way. It may be possible to
determine which channel that has been inverted with some, but not
perfect, assurance if the recorded signal is naturally asymmetric.

> CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
> "Possibly the world's least impressive web site": George Perfect


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************
Anonymous
January 12, 2005 6:11:38 PM

Archived from groups: rec.audio.pro (More info?)

siguy wrote:

> an easier route would be to usa a program like audition or pro tools or
> anything and use a phase canceler/converter/changer/whatever plugin to
> adjust the phase and just move the slider a little and listen. i would
> personally use the phase analysis tool in audition as it will tell you
> to an extreme degree of accuracy wether the tracks are in phase or not.
> they may also be 180 degrees out of phase as thworing may have been
> mixed up somewhere alon your signal path.
> < ....snip.. >

Hmmm, this has me wondering: What phase analysis tools are out there
in common use? For that matter, are there any good articles or books
that address phase issues in modern audio work [i.e.: radio, live sound,
mastering etc.] ?
I'd like to learn a bit more on the subject, both theory and applied.

Later...

Ron Capik
--
Anonymous
January 12, 2005 7:50:59 PM

Archived from groups: rec.audio.pro (More info?)

One of the best phase-analysis tools is an oscilloscope -- left channel to
vertical, right to horizontal.
Anonymous
January 13, 2005 12:31:53 AM

Archived from groups: rec.audio.pro (More info?)

Scott Dorsey wrote:

> RD Jones <annonn@juno.com> wrote:
> >Ron Capik wrote:
> >> Hmmm, this has me wondering: What phase
> >> analysis tools are out there in common use?
> >
> >Soundcraft's small B100 and BVE100 broadcast
> >mixers have an onboard phase meter.
>
> Yes, and there are a lot of the outboard meters like the Dorrough and
> RTW meters that have basic phase metering. I never found these to be
> all that useful, though. They don't really tell you anything that mono
> summing doesn't tell you, and they aren't any help for getting a sense
> of stereo imaging in bad monitoring situations.
>
> An X-Y display like the Tektronix audio monitor is very useful for getting
> a sense of stereo imaging when you can't trust your monitors, and it can be
> very handy for broadcast and record-cutting work where the sum and difference
> channels are asymmetric. But you very seldom see them any longer.
> --scott
> --
> "C'est un Nagra. C'est suisse, et tres, tres precis."

So in effect you're saying that, despite all this talk about group delay
and such, there aren't any tools in common use that quantify these
effects?

Later...

Ron Capik
--
Anonymous
January 13, 2005 12:31:54 AM

Archived from groups: rec.audio.pro (More info?)

Ron Capik <r.capik@worldnet.att.net> wrote:
>
>So in effect you're saying that, despite all this talk about group delay
>and such, there aren't any tools in common use that quantify these
>effects?

Uhh... wait.

I was talking about devices that indicate relative phase between channels.

Which has nothing to do with group delay (phase distortion), although it
can tell you about polarity errors.

All of which are three different things.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
January 13, 2005 4:10:31 AM

Archived from groups: rec.audio.pro (More info?)

William Sommerwerck wrote:

> One of the best phase-analysis tools is an oscilloscope -- left channel to
> vertical, right to horizontal.

OK, but how does one quantify said output?

Later...

Ron capik
--
Anonymous
January 13, 2005 4:10:32 AM

Archived from groups: rec.audio.pro (More info?)

Ron Capik <r.capik@worldnet.att.net> wrote:
>William Sommerwerck wrote:
>
>> One of the best phase-analysis tools is an oscilloscope -- left channel to
>> vertical, right to horizontal.
>
>OK, but how does one quantify said output?

This is what the Tek phase display does.... it's really a scope in disguise.

If a signal is mono and common to both channels, you get a diagonal line /.
If it's got reversed polarity, you get a reversed line \.
As there are phase differences between channels, the line opens up into a
circle.

With some practice you get a sense of what things should look like with
a minimalist miking set, which can help you place mikes when you cannot
trust the imaging of your speakers in the field.

You also get a sense of problems like out-of-phase bass. If the display
skews vividly northwest when there is a kick drum hit, you have a problem
trying to cut that to LP.
--scott


--
"C'est un Nagra. C'est suisse, et tres, tres precis."
Anonymous
January 13, 2005 9:43:30 AM

Archived from groups: rec.audio.pro (More info?)

In article <41E5CA05.E1A32E1C@worldnet.att.net> r.capik@worldnet.att.net writes:

> > One of the best phase-analysis tools is an oscilloscope -- left channel to
> > vertical, right to horizontal.
>
> OK, but how does one quantify said output?

With your ears.

With a fixed delay between two sources containing the same signal, the
phase difference will vary with frequency, so you can really only
quantify the phase shift at a single frequency. An oscilloscope
display of a Lissajous pattern as William describes will show you a
trend. If the display tilts toward the right, the trend is toward "in
phase." If it tilts toward the left, the trend is toward "out of
phase."

If you want to know how many degrees at a fixed frequency, you can
display the reference on one channel of a dual channel scope and the
"shifted" signal on the other channel, measure the time delay between
them, then calculate the phase by dividing the delay by the period
(1/frequency) then multiplying by 360 degrees.



--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
January 14, 2005 6:29:56 PM

Archived from groups: rec.audio.pro (More info?)

On Thu, 13 Jan 2005 01:10:31 GMT, Ron Capik <r.capik@worldnet.att.net>
wrote:

>> One of the best phase-analysis tools is an oscilloscope -- left channel to
>> vertical, right to horizontal.
>
>OK, but how does one quantify said output?

Why do you want numbers? The display will tell you what's wrong and
when you get it right. So will your ears.

But 'scopes do have calibration marks.

CubaseFAQ www.laurencepayne.co.uk/CubaseFAQ.htm
"Possibly the world's least impressive web site": George Perfect
Anonymous
January 15, 2005 6:00:04 AM

Archived from groups: rec.audio.pro (More info?)

Laurence Payne wrote:

> On Thu, 13 Jan 2005 01:10:31 GMT, Ron Capik <r.capik@worldnet.att.net>
> wrote:
>
> >> One of the best phase-analysis tools is an oscilloscope -- left channel to
> >> vertical, right to horizontal.
> >
> >OK, but how does one quantify said output?
>
> Why do you want numbers? The display will tell you what's wrong and
> when you get it right. So will your ears.
>
> But 'scopes do have calibration marks.
>

Well, first off I didn't say I needed "numbers", but the simple answer to
that question is: I don't know. The more complete answer is that I spent
way too many years in a physics lab documenting experimental details
before I entered the more artistic world of audio engineering. When doing
new experiments one never quite knows exactly what data will be needed
or how it may fit an evolving model.
Seems I've carried that over to my corner of the audio world. The x-y scope
shows a real time image of a complex stereo stream. Trends can be seen
in the x-y plot; the plot has an average slope and some shape. So what
information can we take away from this slope and shape? can we correlate
the slope and shape to what we are hearing?
A 45 degree line correlates to mono program material, vertical or horizontal
show just one active channel. A properly phased stereo stream would bounce
about in the first and third quadrants. The extent of excursions from 45 degrees
tells something about the stereo width (or sound stage) ....ummm, etc.
What if there's stuff in the 2nd and 4th quadrant? How much of that can be
allowed before radio stations balk? If the tracks have a temporal offset,
what would that look like?

There may even be statistical programs out there that quantify this
stuff. Don't know...
Maybe I'll find that I have an x-y shape preference for a given musical
style. Don't know...
If I don't take the data I may never know...
I'd hope the x-y scope is more useful (and subtle) than just a way to check for
polarity errors. [But maybe I'm wrong.]

OK, that's just a fraction of the odd questions floating about in my head.

Later...

Ron Capik
--
Anonymous
January 15, 2005 7:31:58 AM

Archived from groups: rec.audio.pro (More info?)

On Sat, 15 Jan 2005 03:00:04 GMT, Ron Capik <r.capik@worldnet.att.net>
wrote:

<lots of very cool thoughts>

If I could add just one: the X/Y scope plot is a visual
representation of a M/S microphone's raw output.

Or, if I could add another, the stereo phono cartridge's
raw output. (Although it's geometrically matrixed, usually
((but there is at least one exception)), and was likely
invented by a guy named Bloomline, or something, so,
go figure.)

Chris Hornbeck
"Happiness isn't something you experience; it's something you remember."
-Oscar Levant
Anonymous
January 15, 2005 8:12:53 AM

Archived from groups: rec.audio.pro (More info?)

> Seems I've carried that over to my corner of the audio world. The x-y scope
> shows a real time image of a complex stereo stream. Trends can be seen
> in the x-y plot; the plot has an average slope and some shape. So what
> information can we take away from this slope and shape? Can we correlate
> the slope and shape to what we are hearing?
> A 45 degree line correlates to mono program material, vertical or horizontal
> show just one active channel. A properly phased stereo stream would bounce
> about in the first and third quadrants. The extent of excursions from 45
degrees
> tells something about the stereo width (or sound stage) ....ummm, etc.
> What if there's stuff in the 2nd and 4th quadrant? How much of that can be
> allowed before radio stations balk? If the tracks have a temporal offset,
> what would that look like?

You've figured out most of this for yourself...

Assume two mics on one instrument. If the two channels have exactly the same
amplitude and phase (ie, they're the same signal), they form a straight, thin
line at 45 degrees. Phase errors turn the line into an ellipse, which becomes a
circle at 90 degrees. I'm not sure what the visible effect of timing errors
would be, but I'm certain it would be much more complex.

The "stuff in the 2nd and 4th quadrant" is the anti-phase or random-phase
components, which are principally due to ambience, reverberation, etc. Relative
errors between the channels also contribute to the 2nd and 4th quadrants.

Note that recordings deliberately encoded for surround sound will show
significantly more signal in the 2nd and 4th quadrants.

Think of the 1st and 3rd quadrants as direct sound, the 2nd and 4th as ambience.
That's an over-simplification, but it's a good starting point.
Anonymous
January 15, 2005 8:14:00 AM

Archived from groups: rec.audio.pro (More info?)

> If I could add just one: the X/Y scope plot is a visual
> representation of a M/S microphone's raw output.

If you think of the 45-degree motion as the M, and motion at right angles to
that as S.
Anonymous
January 15, 2005 2:09:32 PM

Archived from groups: rec.audio.pro (More info?)

In article <41E886AD.34FE4F14@worldnet.att.net> r.capik@worldnet.att.net writes:

> Seems I've carried that over to my corner of the audio world. The x-y scope
> shows a real time image of a complex stereo stream. Trends can be seen
> in the x-y plot; the plot has an average slope and some shape. So what
> information can we take away from this slope and shape? can we correlate
> the slope and shape to what we are hearing?

Not much. We can tell if the trend is "wrong" but your ears can tell
you that, too, if you have decent monitoring. Sometimes, though, it's
easier to get a clue from the visual display that there's something
that you should listen for and make a subjective judgement. You can
listen to a stereo recording with the polarity of a channel reversed
and to someone who's astute, it will sound wrong. But some people who
are unaware that polarity is an issue hook up their speakers wrong
when they take the stereo out of the box and leave it that way for 20
years until they move. Someone who knows can listen to that and
recognize the problem instantly.

Where it starts becoming truly wrong is when you can no longer hear
things. If, for example, a bass is recorded with a mic and a DI
combined in mono (or even panned around the center in stereo), and
either due to position of the mic or careless wiring or routing, at
the lowest frequencies, the phase relationship of the two signals is
near 180 degrees and they're near the same amplitude, you'll get
noticable cancellation of those frequencies. But you probably already
know that. If you see the scope display tilting to the left when you
bring up the second of the two bass channels in the mix, it's time to
take a closer listen to the bass to see if you're getting the effect
you want (you may want to null out some lows). A good engineer will
hear what's happening immediately, but some may not, in the heat of
the moment.


--
I'm really Mike Rivers (mrivers@d-and-d.com)
However, until the spam goes away or Hell freezes over,
lots of IP addresses are blocked from this system. If
you e-mail me and it bounces, use your secret decoder ring
and reach me here: double-m-eleven-double-zero at yahoo
Anonymous
January 16, 2005 7:33:13 PM

Archived from groups: rec.audio.pro (More info?)

AEA makes an XY scope for observing phase called the Winkie Blinkie.
Has anyone here used one of those? If so, how well did it work?
Thanks
!