[David Grant]

I'm interested in knowing more about this tool and how I can use it on
location recordings. Google's not been very helpful.

I understand the way it functions, how a mono signal appears as a vertical
line, how an out of phase signal appears horizontally, how a wide oval
represents a wider stereo image than a narrow oval, but apart from that I
don't know what useful interpretations can be made from this device.

Any wisdom out there that cares to share itself with me?

[Scott Dorsey]

David Grant wrote:
I'm interested in knowing more about this tool and how I can use it on
location recordings. Google's not been very helpful.

There actually was a big discussion of phase scopes here in the early
90's, led by Gabe Weiner.

I understand the way it functions, how a mono signal appears as a vertical
line, how an out of phase signal appears horizontally, how a wide oval
represents a wider stereo image than a narrow oval, but apart from that I
don't know what useful interpretations can be made from this device.

It is very much subjective. About all you can really tell is roughly
how great the out of phase information is compared with the in-phase
information, and how great the level differences between channels are.

Any wisdom out there that cares to share itself with me?

Hook a CD player up to a scope and listen to a bunch of minimalist
recordings and watch what happens. The difference between X-Y and A-B
is very obvious, but look at what happens with near-coincident stuff.

You can get a rough idea of the stereo image, and you can see if anything
is catastrophically wrong, which is better than nothing. It's no
substitute for proper monitoring, but in the field you often don't have
proper monitoring.
--scott

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

[Mike Rivers]

David Grant wrote:

I understand the way it functions, how a mono signal appears as a vertical
line, how an out of phase signal appears horizontally, how a wide oval
represents a wider stereo image than a narrow oval, but apart from that I
don't know what useful interpretations can be made from this device.

That's about it. Unless you're looking at constant tones, you can't
really make any measurements with it. The idea is that it's easy to see
if you have a mic out of phase enough to cause trouble. But you should
be able to hear that, too. Kind of like a way to call your attention to
a problem that you should be hearing.


--
If you e-mail me and it bounces, use your secret decoder ring and reach
me he
double-m-eleven-double-zero at yahoo -- I'm really Mike Rivers
)

[DougD]

In article , "David Grant" wrote:
I'm interested in knowing more about this tool and how I can use it on
location recordings. Google's not been very helpful.

I understand the way it functions, how a mono signal appears as a vertical
line, how an out of phase signal appears horizontally, how a wide oval
represents a wider stereo image than a narrow oval, but apart from that I
don't know what useful interpretations can be made from this device.

Any wisdom out there that cares to share itself with me?


Just to get you squared away a bit. A vectorscope is used in video
to check for chroma (color) phase errors. What you're thinking of
is a phase meter or scope looking for audio phasing errors. They
aren't the same in the way they operate (under almost all
circumstances).. I.e. they're not interchangable.

d.

[Paul G.]

On Fri, 7 Nov 2008 15:41:38 -0500, "David Grant"
wrote:

I'm interested in knowing more about this tool and how I can use it on
location recordings. Google's not been very helpful.

I understand the way it functions, how a mono signal appears as a vertical
line, how an out of phase signal appears horizontally, how a wide oval
represents a wider stereo image than a narrow oval, but apart from that I
don't know what useful interpretations can be made from this device.

Any wisdom out there that cares to share itself with me?


Not exactly wisdom, but...... Years ago ('70's), I used to take old
black and white TV's, and modify them to convert the display so that
one audio input controlled the vertical, and one controlled the
horizontal. I used the existing vertical amp as one channel. The
normal audio output was wired to the horizontal yoke coil.
The display basically looked like a ball of yarn twisting and
gyrating to the music. On some music, especially with lots of low
frequency, you could get fundamental geometric shapes. Mono gave an
approximate 45 degree tight oval (there was quite a bit of phase shift
in the modified TV circuit).
In those days, a lot of dope was smoked, the thing was christened a
"freakscope". It was "de rigueur" to have the thing on when any music
and dope was present. The guys (and few girls) could watch it for
hours. I hacked about 3 or 4 old TV's into freaksopes. Once all us
wannabe hippies got jobs and married, the TV things disappeared, and
they became funny memories that we dredge up now and then!
As far as a tool to evaluate audio systems (including proper
oscilloscopes in X-Y mode), they were pretty useless. The human
hearing system is quite tolerant of weird phase response (all those
room reflections play hell with the phase, but we don't seem to
notice). As stated in another post, a true vectorscope is a tool used
to diagnose colour demodulation problems on colour TV's. Although I
worked a number of years in TV repair, a vectorscope is one of the few
tools I never used.

-Paul G.

[Mike Rivers]

DougD wrote:

Just to get you squared away a bit. A vectorscope is used in video
to check for chroma (color) phase errors. What you're thinking of
is a phase meter or scope looking for audio phasing errors.

Picky, picky. Of course they're not the same, but more than one software
package (usually "mastering" software) has a phase meter that they call
a "vectorscope." It's another pop culture corruption.

There are several variations on the display. Some emulate an
oscilloscope display of a Lissajous pattern, some (probably what
prompted the name "vector") use a line that tilts rather than spreads as
it does with the Lissajous pattern. And then there's that odd jellyfish
display that people who understand it seem to love. But basically they
all display a representation of the phase relationship between the left
and right channels of a stereo audio signal.

[DougD]

In article , Paul G. wrote:

notice). As stated in another post, a true vectorscope is a tool used
to diagnose colour demodulation problems on colour TV's. Although I
worked a number of years in TV repair, a vectorscope is one of the few
tools I never used.

-Paul G.

Well, they're value is mostly in video production where you have to
keep the chroma locked up on muiltiple camera/VTR production.
I.e. checking individual camera's against the studio reference bars
and then correcting the phase errors if present. And also for keeping
an eye on frame sync's for out of house sources (handhelds on a
playing field)...

d.

[DougD]

In article , Mike Rivers wrote:
DougD wrote:

Just to get you squared away a bit. A vectorscope is used in video
to check for chroma (color) phase errors. What you're thinking of
is a phase meter or scope looking for audio phasing errors.

Picky, picky. Of course they're not the same, but more than one software
package (usually "mastering" software) has a phase meter that they call
a "vectorscope." It's another pop culture corruption.

Yeah, I know... I was just thinking maybe why his seach for using a proper
phase meter on Google was not giving him the results he expected if
he was searching on vectorscope..

d.

[Scott Dorsey]

DougD wrote:
In article , Paul G. wrote:

notice). As stated in another post, a true vectorscope is a tool used
to diagnose colour demodulation problems on colour TV's. Although I
worked a number of years in TV repair, a vectorscope is one of the few
tools I never used.

Well, they're value is mostly in video production where you have to
keep the chroma locked up on muiltiple camera/VTR production.
I.e. checking individual camera's against the studio reference bars
and then correcting the phase errors if present. And also for keeping
an eye on frame sync's for out of house sources (handhelds on a
playing field)...

You're actually _supposed_ to use them when you do full alignment of TV
sets and monitors, to make sure the right colors on the color bar fall
into the right voltages on the CRT grids.

But nobody does... they just adjust the gains and pedestals until the
picture looks right. Which, given the vagueries of NTSC anyway is
probably just as good. The customer is going to take it home, crank
the chroma way up and turn the tint half the way to green anyway, just
like my father does.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

[DougD]

In article , (Scott Dorsey) wrote:


You're actually _supposed_ to use them when you do full alignment of TV
sets and monitors, to make sure the right colors on the color bar fall
into the right voltages on the CRT grids.

Well, in most production studios/trucks, there is the advantage that
most monitors have an auto setup to reference bars. So once all
sources are phase locked to house sync, it's then just a one button
setup of the monitors. I have done them by eyeball, but when you
have 20-30 monitors on the wall, that get's a bit tedious with
the clock ticking down. VC's, EIC's typically get one hour at the
most in their call prior to showtime, and the camera/ccu's take
up almost all of that.


But nobody does... they just adjust the gains and pedestals until the
picture looks right. Which, given the vagueries of NTSC anyway is
probably just as good. The customer is going to take it home, crank
the chroma way up and turn the tint half the way to green anyway, just
like my father does.

Why they never included a blue gun only switch with built in bars on
consumer sets (or at least higher end ones) has always amazed
me. Not that most folks would take advantage, but for those that
did care they could at least make it easy with minimal cost. I guess
they assumed that if left at factory defaults most folks would be in
the ballpark, but that's rarely the case.

$.02
d.