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New member Username: Perplexed22Post Number: 2 Registered: Sep-06 | During a visit to a Magnoia Street store this past week one of the sales folks made the comment that Digital Coax will provide a better quality connection and better sound than Optical Digital due to the lack of associated diodes/decoders involved in the Optical transfer process. Does anyone out there have any quantifiable data on this one? Or, (and I know this is a dangerous question) any practical experience comparing the two digital audio transfer methods? |
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Silver Member Username: PraetorianCanada Post Number: 412 Registered: Dec-05 | Practically, no diff whatsoever. Sorry, no quantifiable data to back this up. I use both as I have 4 components and 3 of each inputs, as it happens I used two and two, and while I have not switched them around, the SQ is the same from ea device. |
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Gold Member Username: SamijubalPost Number: 3036 Registered: Jul-04 | Either way, it's just 0s and 1s. I've used both, I don't hear any difference. Optical is less prone to interference. |
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Gold Member Username: John_sColumbus, Ohio US Post Number: 1081 Registered: Feb-04 | A few months ago my jaw dropped when I read in "The Perfect Vision" magazine a FAQ article concerning home theater audio under the question "How can I get the best possible sound quality from my theater system for music listening?" the following: "....be sure to connect the DVD player to the receiver with a coax cable...." I cannot provide a link to this article, but I can quote this post on the AVGuide forum by the writer of the abovementioned article Robert Harley (and TPV's Editor-in-Chief): I received this reader letter and wanted to share it with our group on the AVguide forum. It's a common (and natural) question with a very interesting answer. Editor: First, I'd like to say I'm a long-time subscriber to "The Perfect Vision". I also own & have read Robert Harley's books. I have a question though. In the Winter 2006 issue on page 15 in regards to "How can I get the best possible sound quality from my theater system for music listening?", Robert Harley states that "we" should use the coaxial digital connection for audio from a DVD player because the optical (TosLink) connection introduces timing variations (called "jitter") in the clock that degrades sound quality. I posted this info on a forum & got this response: Go to any studio, even the very studios producing the DVDs we watch at home. You will find a large number of Toslink connections for digital audio as well as some XLR connections (AES/ABU) for digital. Toslink is a common standard for 8 channel, 24bit, 48kHz audio called ADAT. That is 6.5 times more bandwidth than we use Toslink for at home. Why would they use it so often if it were inferior in every way? I respect Mr Harley alot. Is this "clock" in controllers bad in some and good in others? Is the same "clock" in the controllers used for coaxial & Toslink? Can you or Mr. Harley expand on this statement? Thanks for your time & hope to learn more. JF Dear Mr. F: TosLink is just fine for connecting two digital devices so long as the receiving unit is not a digital-to-analog converter. TosLink accurately gets the bits from one place to another, but the problem with TosLink arises because the clock embedded in the signal (it's more accurate to say the audio data are embedded in the clock) loses its timing precision in the TosLink interface. This clock is recovered in the digital-to-analog converter (usually by a PLL, which, by its very nature, tracks variations in the incoming signal) where it becomes the master reference clock for the DAC. The "word clock" (352.8kHz in an 8-x oversampling DAC) that controls when the samples are converted to analog is derived from the clock transmitted in the interface. Jitter in the interface translates to jitter in the word clock, unless heroic efforts are employed. This is why some high-end digital products use a separate clock line, or use the DAC as the reference for the source. Humans are extremely sensitive to tiny timing variations in the reconstruction of digital samples into music. Note again that if the data are not being converted to analog, interface jitter is not an issue. The exact mechanism by which interface jitter affects audio quality is spelled out in great detail in the Audio Engineering Society paper "Is the SPDIF/AES-EBU Interface Flawed" by Chris Dunn and Malcolm Hawksford. It is a fascinating and pioneering piece of work, available at www.aes.org. What's particularly interesting is that the jitter is highly correlated with the audio signal. In experiments I performed with a custom jitter analyzer (it acts as an FM tuner, with the clock as the carrier frequency and the jitter as the modulated component), I could listen to just the jitter component on the interface and identify the music. This AES paper finally quieted the engineering types who insisted that if the bits are the same, the sound must be the same. By the way, the first audio writer to discover that TosLink sounded inferior to coaxial connection was J. Gordon Holt in the first published review of a separate DAC and transport back in the mid-1980s. He new nothing about the technical issues, but simply reported what he heard. Robert Harley http://forums.avguide.com/viewtopic.php?p=199&sid=8d24e7e78a7ea98f325daedee19968 91#top Scroll halfway down the thread. |
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New member Username: TommyvRowlett, Texas Post Number: 4 Registered: Aug-06 | Having said this (and im sure this has been covered before) is there any advantage to buying the "digital coax" cables? I have my DVD player hooked to my reciever using a single monster audio cable and it seems to be transferring the digital signal fine. |
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Silver Member Username: PraetorianCanada Post Number: 415 Registered: Dec-05 | In that case, then, no. |
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Gold Member Username: SamijubalPost Number: 3038 Registered: Jul-04 | Answer this then. If digital coax is better, how come TOSLink is used on more equipment? It's not because it's cheaper. Everything I've owned with a digital output, I've owned more than a few DVD players and recorders, have all had optical out, they didn't all have coax out. |
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Gold Member Username: John_sColumbus, Ohio US Post Number: 1082 Registered: Feb-04 | Answer this then. If digital coax is better I didn't say coax was better...Mr. Harley said that. You'll have to ask him. Personally I don't have a freakin' clue. I have neither the equipment nor, more importantly, the ears to hear any difference there may be. how come TOSLink is used on more equipment? This may be true, but I'm not so sure. I've always made it a point to buy DVD players with both, to ensure maximum hookup flexability. I have noticed that most dirt-cheap $30ish players have coax only. And for the last ten years all my digital cable boxes made by Pioneer or Scientific Atlanta have coax digital outputs only. It's not because it's cheaper. As the below article points out, TosLink isn't that expensive to build into equipment. The article seems to state that jitter was a problem early on, but not so these days. http://www.audioholics.com/techtips/audioprinciples/interconnects/toslink.php Really, the TosLink/SPDIF thing is just another format war, this time between Toshiba and Sony. |
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Gold Member Username: SamijubalPost Number: 3040 Registered: Jul-04 | You said it yourself, most cheapie players have digital coax because it's cheaper, the connector alone is cheaper. I've definitely seen more equipment with TOSLink. |
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Silver Member Username: PraetorianCanada Post Number: 416 Registered: Dec-05 | Whoopedeedoo. John is not promoting one or the other. Your trying to start a flame war with someone who has nothing invested in the answer. Yeeesh. |
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Gold Member Username: SamijubalPost Number: 3042 Registered: Jul-04 | I'm not trying to start anything. Show me anywhere on this board where I've had a flame war with anyone. You need to take a chill pill. |
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Silver Member Username: PraetorianCanada Post Number: 420 Registered: Dec-05 | Your belligerently challenging every point he brings up in the most obnoxious manner possible, either you're picking a fight or you're just being a jerk. I don't need to research any of your previous threads, to see how you're acting on this one. I suggest you take that prescription yourself. |
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Gold Member Username: SamijubalPost Number: 3044 Registered: Jul-04 | Give it a rest, stop whining. |
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Silver Member Username: PraetorianCanada Post Number: 423 Registered: Dec-05 | Pretty much the response I expected from you, thanks for not disappointing! Any-who, you like optical, some guy who wrote an article which John posted for info's sake likes coax, I don't hear a diff between the two (neither does John apparently), so its a tie. |