# shielding rca/component video

J

#### J

Jan 1, 1970
0
Greetings!

I'm building a snake box for my rca gear. I'm going from rca female on the
box to a multi cable and probably back again and I can use a panel-mount
rca, solder a shielded (or unshielded?) wire to an output connector (below)
(db 25).

What about a Double shielded twisted pair DB25? if not please recommend an
available cable/connector.

If I use plain unshielded cable inside the (metal) box, could I run into
problems?

Do I have to worry about shielding, say, composite video from component or
audio (-10 or +4) inside the box?

What do you think my distance limitations will be for component video,
composite, -10/+4 audio, digital coax, svideo on the DB25 cable??
I'm thinking 3f patch +1ft in box + 10ft +1ft in box + 3f patch for a total
of 18 Feet.

-Jessop

R

#### Richard Crowley

Jan 1, 1970
0
J said:
I'm building a snake box for my rca gear.

"gear"? audio? video?
I'm going from rca female on the box to a multi cable and
probably back again

"back again"? not sure what that means? back where?
"the box"? can you give us a better hint what you are doing?
and I can use a panel-mount rca, solder a shielded (or
unshielded?) wire to an output connector (below)
(db 25).

What is the signal? audio? video? something else?
"output connector"? output to where? what kind of cable
does the db25 connect to?
What about a Double shielded twisted pair DB25?

DB25 connectors are neither shielded or non-shielded.
DB25 connectors are neither twisted pair or otherwise.
You seem to be describing some sort of cable which
connects to the DB25?
if not please recommend an available cable/connector.

You have left out too many details for us to have any idea
what you are trying to do here?
If I use plain unshielded cable inside the (metal) box, could
I run into problems?

What kind of signal? audio? video? something else? How far?
Do I have to worry about shielding, say, composite video
from component

If they are the same picture, probably not.
If they are different video signals, then, probably yes.
or audio (-10 or +4) inside the box?

Depends on how far from the video.
I would use shielded cable just to be safe.
What do you think my distance limitations will be for component video,
composite, -10/+4 audio, digital coax, svideo on the DB25 cable??

We have no clue what your "DB25 cable" is.
I'm thinking 3f patch +1ft in box + 10ft +1ft in box + 3f patch
for a total of 18 Feet.

You have provided only ~40% of the details necessary to answer
the nature of the 10 ft of snake cable than about the details of the
boxes and connectors.

J

#### J

Jan 1, 1970
0
My goal is a box to which I can connect my stereo receiver inputs and
outputs that will simplify the connection from one entertainment cabinet to
another - condensing to a single cable (my dreaded DB25 cable . Then
there's a box on the other end of the multicable which expands the
connectors back out to their respective composite video, svideo, component
video, audio(red white), digital multichannel audio, etc. rca panelmount
connectors.

My question is:
While building the box 1) Must I shield individual lines soldered from rca
panel-mounts to my db25 connector inside the metal box, AND 2), Would a
doubleshielded twisted pair cable (with db25 connector, standard issue
printer switch cable) effectively transmit things like component, composite,
svideo, digital audio which were originally on 75ohm coaxial cables?

How effective is shielding on a cable when the + solder points are not
shielded inside of a box?

I plan to make the connections in the box with Belkin 8451. 22 ga shielded 2
conductor.

Respectfully,
Jessop

PS
I very much respect the people involved on these lists. I expect very
little as I know that it is charity. I understand, and have for years, that
I am poorly organized -as are my writings, but you are making sport of my
question. Before writing this paragraph, I looked at your other posts.
People, indeed, ask a lot of stupid questions, and you are quick to point
out that they need to pause and reorganize. However, if you read the entire
you'll see that your ostensible bewilderment is not justified in all cases.
What kind of gear was implied when I asked about specific signal types:
Component video, Composite, Svideo, and audio -10,+4. Translation from one
set of discrete connectors to a unified multi-cable and 'back again' to a
bunch of discrete connectors is generally what snakes do. The websites I've
seen are selling twisted pair double shielded DB25M-DB25M cables. I think
you can surmise that a double shielded twisted pair DB25 Cable is some sort
of cable that is double shielded with twisted pairs and DB25 Connectors on
the ends.

R

#### Richard Crowley

Jan 1, 1970
0
My goal is a box to which I can connect my stereo
receiver inputs and outputs that will simplify the
connection from one entertainment cabinet to another -
condensing to a single cable (my dreaded DB25
cable . Then there's a box on the other end of the
multicable which expands the connectors back out
to their respective composite video, svideo, component
video, audio(red white), digital multichannel audio,
etc. rca panelmount connectors.

My question is:
While building the box 1) Must I shield individual
lines soldered from rca panel-mounts to my db25
connector inside the metal box, AND

If you keep the audio at one end and the video at the
other end you *might* be able to get away without
shielding the internal wiring.
2), Would a doubleshielded twisted pair cable
(with db25 connector, standard issue printer switch
cable) effectively transmit things like component,
composite, svideo, digital audio which were originally
on 75ohm coaxial cables?

It is questionable whether it will work acceptably well
for audio in your application. (See more complete
discussion below.) I would bet that it will make a hash
out of any video (particuarly high-quality video) that
you try to run through it.
How effective is shielding on a cable when the + solder
points are not shielded inside of a box?

Still quite effective. It is over the length of the cable
that the shielding is beneficial, not just at the connection
point.
I plan to make the connections in the box with Belkin
8451. 22 ga shielded 2 conductor.

Assuming you mean "Belden", a well regarded maker of
wire and cable. That would be great for the audio lines.
I wouldn't use it for video if I had a choice of proper
coaxial cable (whether 75-ohm or some other impedance
which doesn't really matter for short pieces).
...you are making sport of my question.

No, I was trying to clarify what you are asking. It may
appear to you that some of the information you left out
was not important, but that is because you may not
understand the scope of the questions you are asking.

Now, there ARE some people on Usenet who DO make
sport of people's questions (and far worse). I suggest
that you need to develop considerably thicker skin and
get a pair of asbestos undershorts if you intend to hang
around some of these newsgroups very much. ;-)
specific signal types: Component video, Composite,
Svideo, and audio -10,+4.

If we can assume from your mention of component video
that you have high-end video equipment (as contrasted with
a cheapo 12" TV set), then any thought of running video
through any kind of printer cable should be put out of your
mind. The video will look like a "dog's breakfast" when
you are done and you will have wasted both your time

People frequently come here [I am reading and posting
audio and video cables and whether they are worth the
extra expense. The overwhelming answer is: No, their
high price only enriches the people selling the premium
cables and they do nothing discernable for your audio or
video.

OTOH, you can't expect to run high-quality video over
cable which was never designed for that kind of band-
width or impedance-control. Just as there is a threshold
above with you cannot *improve* your video signals,
so also there is a threshold below which you are just

If you object to the way I cross-examined you or responded
to your questions, I apologize, I was trying to do a complete
job of understanding the circumstances in order to give an
The websites I've seen are selling twisted pair double
shielded DB25M-DB25M cables. I think you can surmise
that a double shielded twisted pair DB25 Cable is some sort
of cable that is double shielded with twisted pairs and DB25
Connectors on the ends.

You are operating so close to the edge that it was not safe
to make that kind of assumption. Those cables are likely
very nice for parallel printers. Maybe even overkill (as
for the "premium" audio and video cables discussed above)

That cable *might* even be OK for audio, although the lack
of shielding between the twisted pairs may give you more
crosstalk than you would like. Particularly with unbalanced
sources and inputs. And running something like an unshielded
tape output and a tape input line next to each other could
even cause oscillation, audible or supersonic, which could
actually damage speaker tweeters or other parts of your system.

I would definitely NOT recommend the type of cable you
want to use for either audio or video use.

If you want to make something that has several audio and
video cables in a long, flat form-factor, you could consider
taking 10-ft lengths of proper audio and video coax and
"weaving" them together with cable-lacing twine, where
the cables form the long dimension, and the lacing twine
weaves across them to hold them in a flexible ribbon shape.

H

#### HangingJester

Jan 1, 1970
0
Richard said:
...
My goal is a box to which I can connect my stereo receiver inputs and
outputs that will simplify the connection from one entertainment
cabinet to another - condensing to a single cable (my dreaded DB25
cable . Then there's a box on the other end of the multicable which
expands the connectors back out
to their respective composite video, svideo, component video,
audio(red white), digital multichannel audio, etc. rca panelmount
connectors.

My question is:
While building the box 1) Must I shield individual lines soldered from
rca panel-mounts to my db25 connector inside the metal box, AND

If you keep the audio at one end and the video at the
other end you *might* be able to get away without
shielding the internal wiring.
2), Would a doubleshielded twisted pair cable (with db25 connector,
standard issue printer switch cable) effectively transmit things like
component, composite, svideo, digital audio which were originally on
75ohm coaxial cables?

It is questionable whether it will work acceptably well
for audio in your application. (See more complete
discussion below.) I would bet that it will make a hash
out of any video (particuarly high-quality video) that
you try to run through it.
How effective is shielding on a cable when the + solder points are not
shielded inside of a box?

Still quite effective. It is over the length of the cable
that the shielding is beneficial, not just at the connection
point.
I plan to make the connections in the box with Belkin 8451. 22 ga
shielded 2 conductor.

Assuming you mean "Belden", a well regarded maker of
wire and cable. That would be great for the audio lines.
I wouldn't use it for video if I had a choice of proper
coaxial cable (whether 75-ohm or some other impedance
which doesn't really matter for short pieces).
...you are making sport of my question.

No, I was trying to clarify what you are asking. It may
appear to you that some of the information you left out was not
important, but that is because you may not
understand the scope of the questions you are asking.

Now, there ARE some people on Usenet who DO make
sport of people's questions (and far worse). I suggest
that you need to develop considerably thicker skin and
get a pair of asbestos undershorts if you intend to hang
around some of these newsgroups very much. ;-)
What kind of gear was implied when I asked about specific signal
types: Component video, Composite, Svideo, and audio -10,+4.

If we can assume from your mention of component video
that you have high-end video equipment (as contrasted with
a cheapo 12" TV set), then any thought of running video
through any kind of printer cable should be put out of your mind. The
video will look like a "dog's breakfast" when you are done and you will
People frequently come here [I am reading and posting
audio and video cables and whether they are worth the
extra expense. The overwhelming answer is: No, their
high price only enriches the people selling the premium
cables and they do nothing discernable for your audio or video.

OTOH, you can't expect to run high-quality video over
cable which was never designed for that kind of band-
width or impedance-control. Just as there is a threshold
above with you cannot *improve* your video signals,
so also there is a threshold below which you are just

If you object to the way I cross-examined you or responded to your
questions, I apologize, I was trying to do a complete
job of understanding the circumstances in order to give an
The websites I've seen are selling twisted pair double shielded
DB25M-DB25M cables. I think you can surmise
that a double shielded twisted pair DB25 Cable is some sort of cable
that is double shielded with twisted pairs and DB25 Connectors on the
ends.

You are operating so close to the edge that it was not safe
to make that kind of assumption. Those cables are likely
very nice for parallel printers. Maybe even overkill (as
for the "premium" audio and video cables discussed above)

That cable *might* even be OK for audio, although the lack
of shielding between the twisted pairs may give you more
crosstalk than you would like. Particularly with unbalanced
sources and inputs. And running something like an unshielded tape
output and a tape input line next to each other could even cause
oscillation, audible or supersonic, which could actually damage speaker
tweeters or other parts of your system.
I would definitely NOT recommend the type of cable you want to use for
either audio or video use.

If you want to make something that has several audio and
video cables in a long, flat form-factor, you could consider
taking 10-ft lengths of proper audio and video coax and
"weaving" them together with cable-lacing twine, where
the cables form the long dimension, and the lacing twine
weaves across them to hold them in a flexible ribbon shape.

J: If you use well shielded audio and video cables, and part of the goal
is to have a nice neat equipment wiring harness, you could pick-up
plastic split-channel or spiral wrap and use that instead of going to
all the trouble of lacing wires. Plastic channel is available in a few
different diameters. Keep the equipment power lines and amplifier output
wires separate from the others. Another step to include is to make sure
that you label all connector ends, this will save your sanity and avoid
guessing games.

J

#### Jasen Betts

Jan 1, 1970
0
Greetings!

I'm building a snake box for my rca gear. I'm going from rca female on the
box to a multi cable and probably back again and I can use a panel-mount
rca, solder a shielded (or unshielded?) wire to an output connector (below)
(db 25).

What about a Double shielded twisted pair DB25? if not please recommend an
available cable/connector.

why not use a SCART plug?

If I use plain unshielded cable inside the (metal) box, could I run into
problems?

Do I have to worry about shielding, say, composite video from component or
audio (-10 or +4) inside the box?
What do you think my distance limitations will be for component video,
composite, -10/+4 audio, digital coax, svideo on the DB25 cable??

how fast is a car with 4 wheels?

Bye.
Jasen

J

#### J

Jan 1, 1970
0
I've only seen scart in pictures. I'm in the US and none of our gear has
it. I'd love to, but it looks like my idea is cost-prohibitive.

4 wheels, right - point taken.

-Jessop

J

#### J

Jan 1, 1970
0
As it stands with my initial design, component, audio, composite, svideo,
and digital between 2 boxes would cost $100 after labor, connectors, etc. To build it properly would cost a lot more, it seems. Assuming you mean "Belden", a well regarded maker of wire and cable. Haven't been getting much sleep... That would be great for the audio lines. I wouldn't use it for video if I had a choice of proper coaxial cable (whether 75-ohm or some other impedance which doesn't really matter for short pieces). ...the scope of the questions you are asking. Evidentally. thicker skin and get a pair of asbestos undershorts if you intend to hang around some of these newsgroups very much. ;-) Donned. What kind of gear was implied when I asked about specific signal types: Component video, Composite, Svideo, and audio -10,+4. If we can assume from your mention of component video that you have high-end video equipment (as contrasted with a cheapo 12" TV set)... I was basing my design on connectors available on the back of sony's new$2000 hifi receiver.
high price only enriches the people selling the premium
cables and they do nothing discernable for your audio or
video.

No monster then, hosa is fine?
I'm too weak to use monster's toothed RCAs anyways.

If you object

I withdraw my objection. Thanks for your patience.
That cable *might* even be OK for audio, although the lack
of shielding between the twisted pairs may give you more
crosstalk than you would like.

That was one of my concerns - what does double shielded mean? I was hoping
the pairs were shielded, then the whole was shielded. Evidentally not.
...weaving...

sounds pretty, but it's not a component you can just 'install'.

NOW I see why the product I'm looking for isn't available. The market won't
meet the price for the quality, variety, and assembly of the components
required. You'd have to charge several grand for one with 48 specialized
connectors and 6 breakout boxes.

I'm just looking for a way to speed hifi installation/ modification. Hoping
there's an alternative to crawling around behind someone's tv and
entertainment center for hours...

Oh well.

-Jessop

J

#### J

Jan 1, 1970
0
yeah, I've seen those. Better than nothing, but not quite the one cable
simplicity I'm looking for. What can I say, I'm a perfectionist and a
malcontent.

-Jessop

R

#### Richard Crowley

Jan 1, 1970
0
J said:
No monster then, hosa is fine?
I'm too weak to use monster's toothed RCAs anyways.

Monster defines the level where you are paying for the
name and not for any discernable benefit to you.

OTOH, if you are a San Francisco 49ers fan, you get the
benefit of going to "Monster Park" where Noel Lee (who
started "Monster Cable") likely has a luxurious skybox.
to support it.

Hosa defines the lower level of acceptable quality. It is
likely OK for fixed-installations (I use it myself), but many
have reported failures (breaking at the moulded connectors)
in repeated portable use.
That was one of my concerns - what does double shielded
mean? I was hoping the pairs were shielded, then the whole
was shielded. Evidentally not.

"Double-shielded" in a (relatively) inexpensive computer
cable almost always means two layers of aluminum foil
over the entire cable. I've never seen a comptuer cable
with individually-shielded pairs. At least not in 30 years.
Digital signals don't need it, so there is no profit in doing it.
sounds pretty, but it's not a component you can just 'install'.

I'd bet that somebody could come up with an efficient cable
"weaving" machine and make a bit of profit providing
custom flat-cable combinations. Could become the next
Noel Lee and have their own sports stadium!

R

#### Ray L. Volts

Jan 1, 1970
0
J said:
Greetings!

I'm building a snake box for my rca gear. I'm going from rca female on
the
box to a multi cable and probably back again and I can use a panel-mount
rca, solder a shielded (or unshielded?) wire to an output connector
(below)
(db 25).

What about a Double shielded twisted pair DB25? if not please recommend an
available cable/connector.

If I use plain unshielded cable inside the (metal) box, could I run into
problems?

Do I have to worry about shielding, say, composite video from component or
audio (-10 or +4) inside the box?

What do you think my distance limitations will be for component video,
composite, -10/+4 audio, digital coax, svideo on the DB25 cable??
I'm thinking 3f patch +1ft in box + 10ft +1ft in box + 3f patch for a
total
of 18 Feet.

-Jessop

Cat5/e STP (Shielded Twisted Pair; each of the 4 pairs is shielded plus a
shield around the bundle) cable would certainly support the bandwidth
requirements, but you'd probably have trouble with the 100-ohm impedance. I
suppose you could rig up some impedance-matching terminations.

Some info on grounding shielded cable:

http://www.epanorama.net/documents/groundloop/cable_shielding.html

R

#### Ray L. Volts

Jan 1, 1970
0
J said:
Greetings!

I'm building a snake box for my rca gear. I'm going from rca female on
the
box to a multi cable and probably back again and I can use a panel-mount
rca, solder a shielded (or unshielded?) wire to an output connector
(below)
(db 25).

What about a Double shielded twisted pair DB25? if not please recommend an
available cable/connector.

If I use plain unshielded cable inside the (metal) box, could I run into
problems?

Do I have to worry about shielding, say, composite video from component or
audio (-10 or +4) inside the box?

What do you think my distance limitations will be for component video,
composite, -10/+4 audio, digital coax, svideo on the DB25 cable??
I'm thinking 3f patch +1ft in box + 10ft +1ft in box + 3f patch for a
total
of 18 Feet.

-Jessop

Also, check these devices out:

http://www.hometech.com/video/av.html

T

#### Tomi Holger Engdahl

Jan 1, 1970
0
J said:
I've only seen scart in pictures. I'm in the US and none of our gear has
it. I'd love to, but it looks like my idea is cost-prohibitive.

4 wheels, right - point taken.

SCART connector and cables are designed to carry video signal
and stereo audio. There are actually wires for audio and
video (composite video) for both directions. And there are
also some unidirectional control signals and RGB video lines for
one direction.

The idea of SCART is good. The real life implementation of
it leaves something to be desired. The connector used for
SCART is not mechanically or electrically very good
(connector gets easily loose when cable is moved and
then pins are not making good contact).

Then some equipment could have designed the use of some
control signals better in their equipment...

And audio/video connections were pretty clear
(composite video and RGB well specified, nicely
degrading to use composite video if one of the
equipment on one end did not support RGB) until someone
later added S-video support for some SCART connectors
on some equipment... not amy equipment support those...
anyway the way S-video was added to scart has caused many
people to wonder why they get blac&white video where
they expect to get color video...

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