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DVD Digital Output - Coax or Optical?

Old 11-13-01, 08:39 AM
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DVD Digital Output - Coax or Optical?

Dumb questions:

Up until now I have been using the regular RCA audio outputs on my DVD player to my receiver.

1. If I add a digital output cable (either coax or optical) do I still need the DVD RCA audio outputs?

2. Which is better: coax or optical? (I suspect optical)

3. What is the point of running DVD S-VHS video input into an HT receiver vs running it directly into the TV?
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Old 11-13-01, 08:53 AM
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If your receiver accepts a digital feed, then yes, you would want to do that by replacing the RCA audio cables.

I use optical, but I have heard that there is really no difference. Coaxial might be a bit more 'sturdy' if that's of a concern...

As far as question 3, I've wondered that at times myself and don't have an answer for you. I run it directly to the TV though.
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Old 11-13-01, 09:05 AM
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I personally have not heard a difference between coax and optical.

Optical cables are more easily damaged so be careful with the routing.
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Old 11-13-01, 10:31 AM
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Same here, I've used both (currently using optical). Can't find a discernable difference.

Agree on the perception than coax seems more sturdy. But, how many times are you shuffling for wires anyways?
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Old 11-13-01, 10:34 AM
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So if I use either digital coax or optical I don't need the RCA audio outs from my DVD player to my HT receiver?
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Old 11-13-01, 11:09 AM
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A few weeks back there were extensive discussion on the topic - of coax vs optical in AVSForum. The general agreement is that coax is a little better, even though most AV systems can not tell the difference. The reason is that with optical connection you go through an additional stage of signal conversion, whereas coax connection does not.

It is also in agreement that a good-quality video-grade RCA cable from Radio Shack is just as good as a $50 digital coax cable on 95% of the AV systems out there.

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Old 11-13-01, 11:15 AM
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Re: DVD Digital Output - Coax or Optical?

Originally posted by 12thmonkey

1. If I add a digital output cable (either coax or optical) do I still need the DVD RCA audio outputs?

2. Which is better: coax or optical? (I suspect optical)

3. What is the point of running DVD S-VHS video input into an HT receiver vs running it directly into the TV?
1. No you don't.
2. coax (see above post)
3. If you have multiple S-Video devices (S-VHS VCR, DVD Player, etc) and only 1 S-Video input on your display device (TV), then you can use the receiver to switch the source. The quality of the switch varies depends on your receiver and TV (you may not be able to see the difference on your TV). Some receivers claim to have Video Enhancement circuitry that "enhances" the video, but usually it just adds a lot of EE so it's worthless.

If both your DVD player and TV have component output/input (3 wires), you should use that instead of S-Video.

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Old 11-13-01, 12:33 PM
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Re: Re: DVD Digital Output - Coax or Optical?

Originally posted by Beeeil



If both your DVD player and TV have component output/input (3 wires), you should use that instead of S-Video.

Just to clarity that is 3 wires for video only. Not composite which is 2 audio / 1 video.

I use optical because my DVD player doesn't support coax. Either one is great.
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Old 11-14-01, 02:01 AM
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Hi,

To add to what the others have said:

Using the optical output of your DVD player is considered to be "advantageous" in situations where you have long runs of cable. The single biggest benefit of the optical cable (over the coax) is that it is immune to interference from power wires and the like. So, if you're running your audio cables from the DVD player at one end of the room (or house) to your receiver at the other end of the room (or house) and are passing a ton of outlets and wires/cables/etc., a optical cable might be a better choice. If it's just a run of a few feet, like the others said, you'll probably want coax because of its increased strength and durability.

BUT, on the other hand, the optical is also a lot more flexible than the coax. So if you're doing some fancy wiring job that requires all sorts of bends and twists, you might want the optical because it can turn sharp corners a lot easier than the coax.

One other thing to consider: It's my understanding that for all practical purposes, a coax is a coax is a coax (not the actual wire, but the stuff going on behind the connector in the DVD player/receiver). So no matter what kind of DVD player/receiver you use, if you're running the coax option, the connection is as good as the connection can be. Optical connections on the other hand vary depending on the quality (or lack thereof) of the circuitry going on behind the optical plug in the DVD player/receiver.

Not sure if I'm helping you or confusing you, but that's what I have to add to the discussion.

My DVD player is not too close to my receiver, so I use the optical option to avoid interference/buzz/etc. I have no complaints.

Good luck.
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Old 11-14-01, 03:16 AM
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Flip a coin - no difference in quality.
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Old 11-14-01, 04:01 AM
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Originally posted by GMLSKIS
Flip a coin - no difference in quality.
I agree. I had Optical on my old DVD player, then got a new one that only has coax. They both sound exactly the same.
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Old 11-16-01, 03:35 PM
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RickG, the coax carries a digital signal. You won't get any "buzz" from "interference," even with a slightly longer run. I suspect the optical cable is more likely to degrade over longer distances (greater than 2m). But if anyone who wants to spend more on optical connectors is certainly free to do so. $^)
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Old 11-16-01, 06:00 PM
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Just make sure you buy a nice optical cable if this is what you decide to use. The optical cables that come with some DVD players contain plastic filaments that don't ensure the same integrity as using glass fibre.
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Old 11-16-01, 06:24 PM
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Originally posted by drmoze
RickG, the coax carries a digital signal. You won't get any "buzz" from "interference," even with a slightly longer run. I suspect the optical cable is more likely to degrade over longer distances (greater than 2m). But if anyone who wants to spend more on optical connectors is certainly free to do so. $^)
Are you sure?

I was under the impression that a coaxial connection does in fact suffer from possible ground loop problems and EMI. Optical does not. Also, when using a coaxial connection you run into a problem with ohms. Not all coaxial cables/RCA jacks are 75 ohms. Again, optical cables do not have this issue.

About optical cables degrading more that coaxial cables over a long run, I'm quite certain this isn't true. Optic cables have VERY low attenuation rates, much more so than coaxial cable. Even with broadcast and telecommunication uses, fiber optics are usually more desirable because they can span longer distances than metal wires with less signal loss. No?
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Old 11-17-01, 12:04 AM
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I was under the impression that a coaxial connection does in fact suffer from possible ground loop problems and EMI. Optical does not.
Pretty much, yeah. An optical cable won't suffer from interference problems because EMI doesn't affect light quanta (duh!). Coax cables can suffer from EMI since it's using a radio frequency wave and there will be some loss/attenuation of the signal. Having said that however this is really only going to be a big deal if a) your equipment is sitting on top of a transformer or a really really powerful electromagnet or b) if you're running the cable 25' or more. Why 25'? Well, I don't know that's what it is for sure with with this type of cable but with cat5 used for networking that is generally considered to be the furthest run possible that doesn't suffer from any noticeable interference. Now I myself don't run my coax for my equipment 25' because a) that would be extremely expensive to get cable for and b) because I don't live in the Biltmore mansion, my rooms are small and manageable. Therefore, I wouldn't worry about EMI with a coax if you're not doing really long runs, if you are then there's probably a good reason and you should talk to an expert about it. As for optical vs coax, under normal HT usage they're practically identical. One more thing, remember that digial outs employ loss reduction/error correction technology that will allow it to recover from small mishaps. I've used both, on a variety of different equipment and never had any problems. Ultimately it's more a matter of personal taste than anything.
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Old 04-14-02, 08:43 PM
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You might still need the analog outputs. If your DVD player plays MP3's on CDR's (and you use this feature), chances are it will not output the sound from those MP3's through the digital connection (because of SDMI).
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Old 04-14-02, 10:12 PM
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Originally posted by GMLSKIS
Flip a coin - no difference in quality.
There was an extensive discussion here about a month or so ago (maybe longer) which resulted in nothing. It doesn't really matter, so just pick whichever one you want and use it. If money is a factor, you might want to just use a metal hanger (you know, one of those that you get at a dry cleaner). Apparently test have proven that you get equal quality at a fraction of the price.
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