...
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
have wasted both your time and your money.
People frequently come here [I am reading and posting
from rec.audio.tech] and ask about very expensive
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
wasting your time and money.
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
accurate answer.
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.
