Useful application of Phase Display

[Ray Thomas]

Wavelab software (and probably others also ?) provide an X/Y Phase Scope
display in the recording window as an option. While it's great fun to watch
this mutating cotton ball in action during recording, what useful info. does
it convey ? I know it can quickly identify an out-of-phase wired mic, but
can it give useful clues about mic placement, spacing between capsules,
phase cancellations off boundary surfaces, etc ? I frequently use spaced
omni mics, and random phase interactions are faithfully rendered and
entrancing to watch but.....what is the most useful information one can
expect to derive from the Phase Display ?
Thanks for any input,
Ray


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[Phil Brown]

>Wavelab software (and probably others also ?) provide an X/Y Phase Scope
>display in the recording window as an option. While it's great fun to watch
>this mutating cotton ball in action during recording, what useful info.
>does
>it convey ? I know it can quickly identify an out-of-phase wired mic, but
>can it give useful clues about mic placement, spacing between capsules,
>phase cancellations off boundary surfaces, etc ? I frequently use spaced
>omni mics, and random phase interactions are faithfully rendered and
>entrancing to watch but.....what is the most useful information one can
>expect to derive from the Phase Display

It can tell you a lt but you have to look at it a lot and learn that way. No
quick way. after about 6 months or so it'll start to make sense.
Phil Brown

[Ray Thomas]

ok......so, it's a Zen kind of a thing then...?
Ray
-------------------------------------------------------------------------
"Phil Brown" > wrote in message
...
>
> It can tell you a lt but you have to look at it a lot and learn that way.
No
> quick way. after about 6 months or so it'll start to make sense.
> Phil Brown


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[WillStG]

(Mike Rivers)

>If you can plug it in so that it's monitoring a specific pair of mics,
>it can tell you a lot about what they're doing. But then, so can
>listening to the mics.
>

Or on your monitor chain, so you can do in-place soloing and check specific
mic combinations and levels.

Will Miho
NY Music & TV Audio Guy
Off the Morning Show! & sleepin' In... / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[Arny Krueger]

"Ray Thomas" > wrote in message

> Wavelab software (and probably others also ?) provide an X/Y Phase
> Scope display in the recording window as an option. While it's great
> fun to watch this mutating cotton ball in action during recording,
> what useful info. does it convey ? I know it can quickly identify an
> out-of-phase wired mic, but can it give useful clues about mic
> placement, spacing between capsules, phase cancellations off boundary
> surfaces, etc ? I frequently use spaced omni mics, and random phase
> interactions are faithfully rendered and entrancing to watch
> but.....what is the most useful information one can expect to derive
> from the Phase Display ? Thanks for any input,

X/Y phase displays can be valuable when adjusting tone arms. Many kinds of
mistracking show up as flat-lining of the squiggle.

X/Y displays of other audio functions, such as the input/output
characteristic of a power amp, can also show various kinds of misbehavior.

[David Morgan \(MAMS\)]

"WillStG" > wrote in message ...
> (Mike Rivers)
>
> >If you can plug it in so that it's monitoring a specific pair of mics,
> >it can tell you a lot about what they're doing. But then, so can
> >listening to the mics.
> >
>
> Or on your monitor chain, so you can do in-place soloing and check specific
> mic combinations and levels.

Offhand, I'd say that even on the 2-bus, if it constantly looks like
a real 'cotton-ball' there are still some sensitivity parameters to
tweak.

DM

[ScotFraser]

<< ok......so, it's a Zen kind of a thing then...? >>

Well, no, it's a real visual analogy of your stereo width, signal strength, &
in-ness through random-ness to out-ness of your stereo phase. It's pretty
intuitive, even more so if the display is rotated 45 degrees anti-clockwise
from a true XY scope orientation.


Scott Fraser

[ScotFraser]

<< Sadly the
advent of the CD has made many engineers unmindful of the phase relationships
in their recordings. >>

This, I think, is one of the major failings in current audio education. If all
would-be engineers had to have their work cut to LP before being allowed to
make CDs I think we'd stop having to hear so much out-of-phase bad stereo.


Scott Fraser

[Mike Rivers]

In article > writes:

> >If you can plug it in so that it's monitoring a specific pair of mics,
> >it can tell you a lot about what they're doing.

> Or on your monitor chain, so you can do in-place soloing and check specific
> mic combinations and levels.

That would work as long as your solo was solo-in-place and the mics
were panned full left and right. It won't tell you much with mics
panned in the same place or even very far off hard L/R.



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[Rob Reedijk]

Arny Krueger > wrote:

> X/Y phase displays can be valuable when adjusting tone arms. Many kinds of
> mistracking show up as flat-lining of the squiggle.

> X/Y displays of other audio functions, such as the input/output
> characteristic of a power amp, can also show various kinds of misbehavior.

Would it be a useful tool for callibrating a stereo compressor like a set
of linked 2254s?

Rob R.

[Scott Dorsey]

ScotFraser > wrote:
><< Sadly the
>advent of the CD has made many engineers unmindful of the phase relationships
>in their recordings. >>
>
>This, I think, is one of the major failings in current audio education. If all
>would-be engineers had to have their work cut to LP before being allowed to
>make CDs I think we'd stop having to hear so much out-of-phase bad stereo.

I think if everyone had a chance to actually hear a speaker system that
had proper imaging and got a sense of what things actually sound like,
we'd see a lot less of it, too.
--scott

--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[Arny Krueger]

"Rob Reedijk" > wrote in message

> Arny Krueger > wrote:
>
>> X/Y phase displays can be valuable when adjusting tone arms. Many
>> kinds of mistracking show up as flat-lining of the squiggle.
>
>> X/Y displays of other audio functions, such as the input/output
>> characteristic of a power amp, can also show various kinds of
>> misbehavior.
>
> Would it be a useful tool for callibrating a stereo compressor like a
> set of linked 2254s?

Sounds like a pregnant application. Never tried it, though.

[David O'H]

"ScotFraser" > wrote in message
...

> Yeah, but I'm told that nobody listens to mono anymore.
> <g>


One of the grand old men of local audio told me recently that he thinks
stereo is bushwah (perhaps not those exact words, but let's say
unnecessary).

He figures that once the volume gets to the point that most pop music is
listened to, all the imaging cues are so reflected and refracted and stuff,
that there's no way to tell which sound came from where originally.

Dave O'H
oheareATmagmaDOTca

[ScotFraser]

<< He figures that once the volume gets to the point that most pop music is
listened to, all the imaging cues are so reflected and refracted and stuff,
that there's no way to tell which sound came from where originally.>>

Yes, although this is not exclusive to loud pop music. Substantial mono summing
takes place in any stereo listening environment, other than headphones or
anechoic rooms. The <g> in my statement was for the several detractors who have
argued against this point with me in the past, claiming mono compatibility is
irrelevant with CDs.


Scott Fraser

[EganMedia]

>Yes, although this is not exclusive to loud pop music. Substantial mono
>summing
>takes place in any stereo listening environment, other than headphones or
>anechoic rooms.

Isn't that the room's doing though, rather than the recording? Any room that
smears a stereo image to the point of "substantial mono summing" would most
likely skew a mono signal pretty substantially too. I'm not arguing for
ignoring microphone phase relationships, but if listening environments are
going to mess up the image that badly, why sweat a little phase phunk in the
recording?




Joe Egan
EMP
Colchester, VT
www.eganmedia.com

[ScotFraser]

<< It wasn't me. Mono compatibility is still imperical in my estimation; it's
just
that CDs don't have to adhere to the same 'cutting' parameters as did records.
Most of the people I know still have small mono table radios and mono portable
TVs, etc.. >>

Beyond those mono devices, many people listen to stereos in non-anechoic
spaces.


Scott Fraser

[Monte McGuire]

In article >,
Rob Reedijk > wrote:

> Arny Krueger > wrote:
>
> > X/Y phase displays can be valuable when adjusting tone arms. Many kinds of
> > mistracking show up as flat-lining of the squiggle.
>
> > X/Y displays of other audio functions, such as the input/output
> > characteristic of a power amp, can also show various kinds of misbehavior.
>
> Would it be a useful tool for callibrating a stereo compressor like a set
> of linked 2254s?

Sure... feed a mono signal to both channels and put the outputs into the
XY display. If the two channels were matched well, the output would
also still be mono (a thin line). If you have any tracking problems,
you'll get something closer to the normal fuzzball that you get when
looking at stereo. Of course, there won't be time differences between
channels, but there will be amplitude differences that will cause the
display to deviate from a straight line.


Regards,

Monte McGuire

[WillStG]

>Monte McGuire

>Sure... feed a mono signal to both channels and put the outputs into the
>XY display. If the two channels were matched well, the output would
>also still be mono (a thin line).

I like to do this with left minus right metering, on my tektronix the meter
showing the summed "minused" signal is a lot more precise in judging level
differences between channels than going by how thin the line on the crt display
is.

Will Miho
NY Music & TV Audio Guy
Off the Morning Show! & sleepin' In... / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[WillStG]

>Monte McGuire

>Sure... feed a mono signal to both channels and put the outputs into the
>XY display. If the two channels were matched well, the output would
>also still be mono (a thin line).

I like to do this with left minus right metering, on my tektronix the meter
showing the summed "minused" signal is a lot more precise in judging level
differences between channels than going by how thin the line on the crt display
is.

Will Miho
NY Music & TV Audio Guy
Off the Morning Show! & sleepin' In... / Fox News
"The large print giveth and the small print taketh away..." Tom Waits

[Phil Brown]

> I like to do this with left minus right metering, on my tektronix the meter
>showing the summed "minused" signal is a lot more precise in judging level
>differences between channels than going by how thin the line on the crt
>display

This is the infamous phase meter so beloved of Rupert Neve. All Neve consoles
used to have one.
Phil Brown