Digital cables

Discussion in 'Archived Threads 2001-2004' started by JJR512, Sep 25, 2002.

  1. JJR512

    JJR512 Supporting Actor

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    I'm about to need my first-ever digital cables. Not exactly sure yet if it's going to be optical or...umm...the other kind...yeah. (I think you can already tell how much I know about digital cables, hmm?) I'm not really interested in a optical vs. other-kind debate, but if I have a choice, is one definitely better than the other, or does it really not matter?

    Actually, my main question is if digital cables come in differing levels of quality. I mean if there's like a generic $5 cable and a super-dooper $100 cable or whatever. I would think that because the data is digital, as long as the signal can get through at all, a higher-quality cable shouldn't be any better than a lower-quality cable, because as long as the data gets through, it's the same data. Am I right in my thinking?

    One other thing: What kind of cable is used for the AC-3 RF signal from an LD player?
     
  2. Phil A

    Phil A Producer

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    A digital cable does not transmit data in digital fashion (there are not 1s and 0s being transmitted) so it is subject to the same problems as an analog cable. As with an cable, a good connector makes a good electrical connection. The RCA on coax is generally a better connector. You also want to use a 75-ohm coaxial cable for digital. You can use the same cable for the AC-3 out.
     
  3. Bob McElfresh

    Bob McElfresh Producer

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    You are correct that a digital signal is much less sensitive to the cable than an analog signal.

    But yes, you can buy a $800 digital interconnect and I do not believe it will make much difference over a $15 video cable on consumer-quality systems.

    The people who designed the coaxial-digital interface for DVD players (called SPDIF - Sony Phillips Digital Interface Format) wanted you to be able to find the cable easially. (Remember: they were TRYING to develop a DVD player to be accepted by the masses, not the rich.) To make it easy - they had a video cable in mind for this connection.

    The AR or Radio Shack brands of video/digital cables work fine.

    The other option is a "Toslink" optical cable. This has some theoretical advantages being light instead of electrical signals, but some listening tests have detected that different optical cables sound a bit different. No good explination was ever given for this. (This is the famous "Bits are Bits? Right?" article in Home Theater Magazine a few years ago.)

    Personally, I think optical has 2 major disadvantages:

    - the fibers are basically glass. Bending them to fit into packages likely causes fractures.

    - the coaxial cable acts to tie the signal-ground between the DVD player to the receiver. This is important for proper signal transfer (both devices have to agree what 0.00 volts is).

    Hope this helps.
     
  4. Lee Petty

    Lee Petty Stunt Coordinator

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    bob, about the bending of fiber. it will be okay as long as the bend is not tighter than 10 times the outside diameter of the jacket. most of the fiber that comes in a package should be fine, especially since it should be gel filled.
    but one other disadvantage of fiber is contamination. dust or fingerprints on the endface can cause up to a 45% loss of light transmission.
     
  5. JJR512

    JJR512 Supporting Actor

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    OK, so: Use coax digital if possible, and use coax digital cable for AC-3 RF. Now the blue-jacketed AR brand at Best Buy should be just fine? What about the Monster Cable brand; haven't seen too many people recommend them, are they just overpriced hype?

    Finally, one new question: What about speaker cables? Is there a general rule of thumb for guage vs. length? Monster Cable seems to be the most readily available brand, is that OK?
     
  6. Lorenzo K

    Lorenzo K Agent

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    AR, Radio Shack or Monster Cable will work fine for coax digital. As for speaker wire just use 12 guage from home depot and you will be good to go.
     
  7. Bob McElfresh

    Bob McElfresh Producer

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    AR makes some very good cables for the price. Grab a video or "digital" cable for the link between your DVD player and receiver.
    Speaker Wire: several speaker sites recommend the following thickness based on the run-lenght:
    1-10 ft: 16 ga
    11-20 ft: 14 ga
    20+ ft: 12 ga
    Most of us just buy a spool of 12 ga wire and use it everywhere. Monster is fine, but a bit over-priced. Home Depot sells some good stuff, but some of it has turned green under the insulation after a few years. The best deal seems to be buying a spool of Sound King speaker wire from www.partsexpress.com .
    Monster Cable: Despite the bashing, Monster is good quality stuff. It's easy to find so you can just run out and grab what you need.
    But the price is somewhat high and they do train/bribe the sales people to push Monster. This is NOT bad business, but they help support some Myths about cables that are either not true, or have very small effects.
    So check here before you buy and we will try to save you money on the less-critical cables (subwoofer, coaxial-digital), and get you to spend more money on the more-important cables (video).
     
  8. JJR512

    JJR512 Supporting Actor

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    A neighbor of mine, a guy who works for Ritz Audio Visual, has also told me that high-priced speaker wire is a lot of money for very little, if any, and also recommended the bulk wire you can get at Home Depot. He specifically recommended to me the SJ type cable (two conductor, obviously, in 12ga). Is that what you guys use, or if not, what specifically do you get from HD?
     
  9. Jeffrey Chin

    Jeffrey Chin Second Unit

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    Also depends on which DAC is better..your preamp's DAC or DVD's DAC

    If Preamp DAC is better, get digital (coax)
    If DVD DAC is better, get analog (RCA)

    Digital coax will bypass DVD DAC and use Preamp DAC
     
  10. JJR512

    JJR512 Supporting Actor

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    I understand about which DAC to use, but as far as the DVD player is concerned, it may be moot, depending on which receiver I get. Specifically, with how many multi-channel inputs it has. If it has only one, it's going to be used by the multi-channel output from my Sony SDP-EP9ES which I'm using for AC-3 RF demod duty for an LD player. Actually, now that I think about it, the EP9ES has a 5.1 bypass input, which if I understand it correctly, takes in a 5.1 channel input and sends it directly to the 5.1 channel output without modification when "bypass" is selected as the input...in other words, if the DAC of the DVD player is really better than the DAC of the EP9ES or whatever receiver I end up with, I could connect the 5.1-ch. output from it to the EP9ES and just connect that unit's 5.1-ch. output to the receiver's 5.1-ch. input and use the EP9ES to select between LD and DVD. How good is the DAC of the Sony SDP-EP9ES? It's obviously an ES unit, so I would expect it would be rather good. I haven't actually purchased a DVD player yet (for this system), but so far I've been planning on the Sony DVP-NS715P. How good is the DAC in that unit, compared to the DAC in the EP9ES? As far as the receiver goes, there's another part I need to actually get. I had originally planned on the Sony STR-DE985 but was turned away from it by the helpful advice here. I'm going to try to stretch my budget to get an STR-DA4ES. So, between the three componenets with DACs that I'll have, which has the best, the second best, and third best?

    (I do of course realize the DA4ES has TWO multichannel inputs, one 5.1 and one 7.1, so I could conceivably use the LD player/EP9ES connected to one and the DVD player connected to the other, but I suspect that this receiver has a better DAC than this relatively low-end DVD player, the NS715P, and probably also better than this older ES unit, the EP9ES.)
     

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