Coax cable question.

May 30, 2004 3:51 AM

Coax cable question inside. (inside, that is!)

I bought a cable to connect my tuner to my DVD player. I got a male-male coax cable (Bandrigde VL 8030) but it was sold to me as a 'video' cable. The icons say:

Wall outlet Socket
AMP
VCR

->

TV
TUNER

Will I toast my equipment with this cable or is it safe to use? In general: is all coax cable the same thing?

posted by NekulturnY to technology (11 comments total)

When I say "tuner", I mean of course: amplifier. Doh.
posted by NekulturnY at 3:52 AM on May 30, 2004

Okay, I've tried searching on Bandridge VL 8030, but couldn't find an image or anything that would describe the cabling to me.

I worry that we have an internationalization nomenclature problem, here, so I am wary of answering without much more specific information.

What would be helpful is this info:

Model of DVD Player
Model of Amplifier
Type of Signal you're connecting from dvd-->amp

The last one is the important part. It's not clear to me at all from your description what you're connecting.

In the US, "coax" is usually used for a very particular type of cabling; typically radio-frequency type stuff that is sensitive to interference, and which needs to be shielded. Antennas are usually connected with coax cabling, as are cable television signals from outlet to box/tv/vcr; and also the radio frequency modulated signal that old-style vcrs and dvd players can send to a TV tuner. These are different kinds of signals than, for example, a line-level video signal or single channel audio signal—these are usually carried by different kinds of cabling with different kind of connectors.

All cabling (but particularly important with coax cabling) varies in its resistance or impedence. In the US, standard cable television coax cabling is 75 ohms resistance, for example.

So, anyway, it's not clear to me if you're routing some rf modulated combined audio/video signal (a la cable tv/antenna signals) from your dvd to your amp (which would then send it to your TV), or something else. Typically, if not using the modulated combined signal (which is crappy quality), then for composite video with stereo audio, there would be three line-level cables (one video, two audio). In the US these would not be called "coax" cabling, although they would likely be shielded (at least the video cable, anyway), and would use what are called "phono" or "RCA" connectors in the US. Other possibilities are an S-Video cable and connector (which has several wires for several independent signals) along with audio cables and connectors; or seperate component video cables and connectors with audio cables and connectors (all "phono" style); or even more exotic varieties. These all move an audio/video signal from your DVD player to your AMP and then, presumably, to your TV.

Other possibilities for your DVD player to your amp regarding audio depend upon whether you are using digital audio, or not. If your amp decodes DTS and/or Dolby digital, then you'd have a single digital-quality cable and connector from the DVD player to the amp. If your DVD player does the decoding, then you might have all 6 or more seperate audio cables and connectors between your DVD player and your amp. But that's rare these days.
posted by Ethereal Bligh at 5:14 AM on May 30, 2004

If your amp decodes DTS and/or Dolby digital,

It does both, yes.

then you'd have a single digital-quality cable and connector from the DVD player to the amp.

Right: that's what I bought the coaxical for.

The video signal and the audio signal are split up: the video signal goes straight to the tv from the DVD player. And then there are two different audio exits on the DVD: one with two cinch cables (red and white), one coaxical. The coaxical is supposed to be better (digital). The AMP can also take an optical IN from the DVD (which is even better, apparently), but my dvd-player doesn't support that.

Is this at all clear? I'm hopeless in this department.

The coax cable says "TV Aerial-Lead" and "High performance 99.96% OFC cable".
posted by NekulturnY at 5:23 AM on May 30, 2004

according to my googling, both digital audio and analog video use the same 75 ohm cable, so you should be fine. see, for example: http://www.smr-archive.com/forum_1a/messages/983.shtml.

in general, as long as plugs fit sockets and you don't connect things that shouldn't be connected together, you're unlikely to damage anything by using the "wrong" cable.
posted by andrew cooke at 6:00 AM on May 30, 2004

You'll be fine as long as you have RCA plugs at both ends. If you have the cable-tv style of connector on the cable, that won't work. Because the connectors won't fit. And you might break stuff if you try to jam them in real good.

Optical isn't really any better than coax digital under normal circumstances; 100011011 is 100011011 however it's transmitted.
posted by ROU_Xenophobe at 12:34 PM on May 30, 2004

Yeah. Home A/V stuff is mostly 75-ohm cable. In other places (e.g. radio) 50-ohm coax is the norm. But you won't damage anything by using a cable of the wrong impedance, as long as the connectors are appropriate (e.g. don't force a "G" connector onto an "F" connector, although they almost fit...) Worst that you'll get is a degraded signal: ghosts on analog video, dunno what happens to a marginal digital audio connection.
posted by hattifattener at 3:36 PM on May 30, 2004

(ROUX — some lunatic salesguy once tried to convince a friend of mine that you should only use coax for digital audio interconnects because the optical would "bruise the bits".)
posted by hattifattener at 3:38 PM on May 30, 2004

Oh, let's not get started with hifi audio cabling myths. Criminy.
posted by Ethereal Bligh at 6:21 PM on May 30, 2004

Yeah, well, there's nothing worse than bruised bits, is there?
posted by dg at 7:45 PM on May 30, 2004

You should be fine. I used to work at Ace hardware, and my boss showed me a nifty trick where he stripped a normal electrical wire down to the thick wire inside. Opened up a box that had the coaxial screwing parts, and viola, you have a coaxial cable for a fraction of the price of a pre-made one. I use the cable and have had no problems with it.
posted by jmd82 at 8:04 PM on May 30, 2004

Thanks.
posted by NekulturnY at 2:15 AM on May 31, 2004