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Digital Output - Coax vs Optical

Old 01-28-02, 02:37 PM
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Digital Output - Coax vs Optical

Is there a difference in sound, is one better than the other?

I have my DVD Player going to my JVC Receiver via TOSLINK Optical. A HDTV receiver I am looking at has SPDIF Optical out, can I connect my DVD via Coax (when I find a cable) and notice no difference?
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Old 01-28-02, 02:47 PM
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Re: Digital Output - Coax vs Optical

Originally posted by theedge
Is there a difference in sound, is one better than the other?
Theoretically, coaxial will sound better (and this is because of the Toslink implementation, rather than the inherent superiority of one kind of cable to another).

Originally posted by theedge
A HDTV receiver I am looking at has SPDIF Optical out
SPDIF = Toslink, which you probably already know

Originally posted by theedge
can I connect my DVD via Coax (when I find a cable) and notice no difference?
Yes. I personally guarantee that you will notice no difference, assuming everything is working properly, and that you're using the JVC DS-TP 450.
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Old 01-28-02, 02:53 PM
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Yep, that's the JVC I am using. It really sounds sweet, much better than I had thought. Thanks for the info.
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Old 01-28-02, 03:36 PM
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i have..

i have a digital (carbon fiber optic T-1 line that fits my token lan ring etheret card- Comic Book Guy, Simpsons) cord. it sounds pretty good although, when u buy it, it will dent you wallet, as it did to me.
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Old 01-28-02, 04:45 PM
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Coax is coax. Any coax cable thats 75 ohm with RCA plugs can fit the bill as a digital audio cable. $4 at Target, that's what mine cost.

I don't know about the sound variations resulting from implementation of technology, but all else being equal, there's no reason coax and optical would sound any different. Digital means 1s and 0s. A 1 is a 1 and a 0 is a 0 regardless of the medium.

I don't understand paying $100 for a toslink cable with "gold-plated" connectors and shielding, when (a) an optical cable does not make conductive connections, nor is an optical signal susceptible to EMF interference.

Likewise digital coax cables. As long as the 1s and 0s get from one end to the other, it's going to sound the same, if the cord costs $4 or $400.
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Old 01-29-02, 08:09 PM
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Ditto what Tee said.

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Old 01-31-02, 04:55 PM
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I have a fiber optic running from my DVD player to receiver and a coaxial from my CD player to the receiver. I can swap them out and notice no difference. Both are GREAT.

Last edited by uteotw; 12-02-02 at 02:17 PM.
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Old 11-29-02, 12:13 PM
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If you buy a 4 dollar cable and notice no diffrence then you system must not be very good. Do you think there would be such a large market for cables if a piece of lamp cord or the cheap wires that come free with the electronics were good enough. If you put enough money into a good system then you would certinly notice diffrences. Back to the point Coax is supposedly better since the current is electrical so there is less layers of processing to convert to light and back. plus they are supposed to be more durable.
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Old 11-29-02, 06:02 PM
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You will only notice a difference between the two if you can hear grass grow.
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Old 11-29-02, 06:09 PM
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but cheap cables may have poorer shielding resulting in interference which can degrade sound
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Old 11-29-02, 06:29 PM
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These are digital signals that are being transmitted. Bits are bits. Either they get from one end of the cable to the other or they don't. This is not an analog signal whose sound can be 'colored' by the quality of the cable.

Any decently-shielded cable will get the job done equally well, regardless of whether it is coax or optical. Any audible difference between the two is purely psychosomatic. There really can't be a difference in sound quality between the two. If the bits are not transmitted properly you don't get sound. End of story.

When you're talking about an analog signal that's a different story.
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Old 11-29-02, 08:34 PM
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interference can affect digital, unless my networking professor in college was full of crap, as the interference can affect if the bits are properly received
it's harder to affect than an analog signal but no impossible
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Old 11-29-02, 08:58 PM
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Originally posted by mikehunt
interference can affect digital, unless my networking professor in college was full of crap, as the interference can affect if the bits are properly received
it's harder to affect than an analog signal but no impossible
However there's a big difference between the interference received with a 100 meter run of CAT5 cable and a 2 meter run of shielded coax. Not to mention the difference between a protocol meant to tolerate collision and retransmission (CSMA/CD) and a realtime audio stream that includes reclocking to prevent jitter (and even error correction in the case of Dolby or DTS).
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Old 12-01-02, 08:37 AM
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Originally posted by Josh Z
These are digital signals that are being transmitted. Bits are bits. Either they get from one end of the cable to the other or they don't. This is not an analog signal whose sound can be 'colored' by the quality of the cable.
Bits is bits, but don't confuse the message with the medium it's being carried over.

You're right, digital isn't analog, but don't think that makes it any less susceptible to interference when using digital coaxial. Regardless of the info being sent, coaxial is an RF medium which can and does have interference. Just like an analog signal traveling on the wire can get screwed with, so can those 1's and 0's. Digital and analog are different, but RF mediums are all the same.

Your receiver has error correction on it, just like any other device on the planet that has an RF digital connection (like your modem, network card, etc.) specifically because 1's and 0's will be dropped in the transmission. One of the major differences between a $200 receiver and a $1000 receiver is going to be that error correction. If you're using digital coax you're hearing your receivers rendition of what it cobbled together from the bits that made it across. You generally won't hear interruptions in the audio, but it might not sound as rich as it could/should.

Digital optical is a true digital medium. 1's and 0's transferred not using RF, but light, which can't be interferred with unless the cable is broken, which results in no signal. You receiver gets every bit sent and the sound you hear is exactly as it was sent from the player. The receiver still has to put it together, but it's got an accurate blueprint of the sound picture to work with, no guessing needed.

When cabling your system you should go with the digital optical whenever possible. As a bonus, a $9 optical cable is usually going to work as good as a $100 optical cable. The major difference is going to be breakability, as no shielding is necessary. As long as you're not constantly fussing with the cable, 11 $9 cables will have a longer combined lifespan than 1 $100 cable.
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Old 12-01-02, 09:28 AM
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When cabling your system you should go with the digital optical whenever possible. As a bonus, a $9 optical cable is usually going to work as good as a $100 optical cable. The major difference is going to be breakability, as no shielding is necessary. As long as you're not constantly fussing with the cable, 11 $9 cables will have a longer combined lifespan than 1 $100 cable.
I have been under the impression that jitter was a much more significant problem when using optical rather than coax and is particularly exacerbated when using cheap optical cable.
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Old 12-01-02, 10:55 AM
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Originally posted by renaldow
You're right, digital isn't analog, but don't think that makes it any less susceptible to interference when using digital coaxial. Regardless of the info being sent, coaxial is an RF medium which can and does have interference. Just like an analog signal traveling on the wire can get screwed with, so can those 1's and 0's. Digital and analog are different, but RF mediums are all the same.

Your receiver has error correction on it, just like any other device on the planet that has an RF digital connection (like your modem, network card, etc.) specifically because 1's and 0's will be dropped in the transmission. One of the major differences between a $200 receiver and a $1000 receiver is going to be that error correction. If you're using digital coax you're hearing your receivers rendition of what it cobbled together from the bits that made it across. You generally won't hear interruptions in the audio, but it might not sound as rich as it could/should.
Renaldow, I'm sorry but this is a big load of bunk. Unless you're running a poorly shielded cable for hundreds of meters, this is not a practical concern for the vast majority of home theater applications. For the 1-3 meters that most people typically run cabling from their DVD player to their receiver, any decently-shielded (i.e. not the cheapo junk that comes free with the DVD player) coax cable will transmit the digital signal fine without dropping bits.

You are yelling "Fire!" in a crowded home theater when there is none.
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Old 12-01-02, 08:18 PM
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Does anyone make a optical to coax adapter? I've used all of the optical slots on my receiver.
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Old 12-01-02, 08:47 PM
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Originally posted by bmello
Does anyone make a optical to coax adapter? I've used all of the optical slots on my receiver.
Check out the last two posts in this thread: http://www.dvdtalk.com/forum/showthr...hreadid=177297

I purchased a coax to optical converter and it works fine for me. It's just TV, so I can't vouch for audio quality...sounds just fine to me though.

Hope that helps.
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Old 12-01-02, 08:50 PM
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not sure, but these places might be worth a look
http://www.l-com.com
http://catalog.blackbox.com/BlackBox...mainscreen.asp

mostly for computer stuff but they have all sorts of converters


Originally posted by bmello
Does anyone make a optical to coax adapter? I've used all of the optical slots on my receiver.

Last edited by mikehunt; 12-01-02 at 08:53 PM.
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Old 12-02-02, 09:53 AM
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Originally posted by X
I have been under the impression that jitter was a much more significant problem when using optical rather than coax and is particularly exacerbated when using cheap optical cable.
I've never experienced jitter, I was always under the impression it was caused by timing problems on the receiver. I can see how some cheaper optical cables could create additional problems because of cheaper connectors that offer no support and let the cable just kind of droop out of the device. Instead of a clean break, it's possible the cheaper material creates a reflection/refraction (whichever) type problem that causes the jitter. No idea if that's possible, just a thought.

Last edited by renaldow; 12-02-02 at 10:32 AM.
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Old 12-02-02, 10:21 AM
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Originally posted by Josh Z
Renaldow, I'm sorry but this is a big load of bunk. Unless you're running a poorly shielded cable for hundreds of meters, this is not a practical concern for the vast majority of home theater applications. For the 1-3 meters that most people typically run cabling from their DVD player to their receiver, any decently-shielded (i.e. not the cheapo junk that comes free with the DVD player) coax cable will transmit the digital signal fine without dropping bits.

It's not bunk at all. RF is an inherently lossy medium. A shielded RF cable offers some protection against the majority of outside interference. It does not offer any protection against itself though. Bend a digital coax cable the wrong way, and it will still seem to work. It may also start sending bad packet data to the receiver.

As for a 1-3 meter cable not dropping any bits... I'd like to see a manufacturer that guarantees that. Even in a 1 meter run bits are going to be dropped on an RF wire, it's the nature of the medium. Again, that's why there's error correction built into hardware devices that use digital RF.

It seems foolish to me not to use an optical cable if that option is available to you. Optical is inherenly a clean medium and it doesn't add to, and isn't effected by, the electrical storm that is your TV, center speaker, receiver, DVD player, VCR, game console and TiVo, cable box, direcTV box, etc.

If it were bunk, would it have been created in the first place? Would it be an option on any device that benefits from its' use? Cabling is the cardiovascular system of your home theater, I assume most of us want the best cables/equipment that we can afford. Since the price of optical cables has dropped in the last couple of years I don't see why anyone would even bother with digital coax if they had the option for digital optical.

You are yelling "Fire!" in a crowded home theater when there is none.

That's pretty good, I like that

Last edited by renaldow; 12-02-02 at 10:24 AM.
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Old 12-02-02, 10:44 AM
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The component video signal is transmitted over the exact same type of RCA coaxial cable, and that seems to get where it's going without incident or the help of digital error correction. You'd think an analog video signal would be much more susceptible to RF interference and would cause very noticeable visual artifacts if this were really such a problem.
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Old 12-02-02, 01:38 PM
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Originally posted by Josh Z
The component video signal is transmitted over the exact same type of RCA coaxial cable, and that seems to get where it's going without incident or the help of digital error correction. You'd think an analog video signal would be much more susceptible to RF interference and would cause very noticeable visual artifacts if this were really such a problem.
You're comparing apples and oranges; or more literally, analog and digital.

Without getting too deep into Analog v. Digital transmissions or data compression...

Analog sources such as the component connection between a DVD player and TV (Yes it really is analog...) travel fairly well through a copper wire, and always have since the invention of the telegraph. Think of analog as low resolution, though. RF signals travel copper wires in a wave pattern, it's inexact information. Interference hits it, the wave changes slightly, but the bulk of the info makes it through OK.

Copper wire can only hold so much information, this is why radio broadcasts sound the way they do, and TV broadcasts look the way they do. Low res is great for copper wires, and is able to stand fluctuations and interference fairly well. You're right, the component cables do a fantastic job of sending that analog Radio Frequency signal from the DVD player to the TV. Mainly because of the fact that the signal has been split into thirds, which allows each 1/3 to have 3x the bandwidth along the wire, as opposed to say composite, which forces the 3 parts to share the same bandwidth of 1 wire. Which is better, composite or component?

Digital is exact information, think of it as high resolution. It's either a 1 or a 0, on or off, and if all that information isn't there and complete then the item it's creating (audio, video, computer file) isn't exact or complete. Copper can carry digital information, but it's generally so slow and low bandwidth that digital sources (computers, DVD players, etc.) compress the 1's and 0's to move more across at the necessary speed. You may have heard the term 'data compression' that's what I'm talking about. When that's travelling across a copper wire and interference hits it, it just doesn't shave a little off the wave like it does with analog, it takes out a chunk of crammed data, which your receiver then has to analyze, decide it's not correct and then looks at what was before it and after it, and then estimates what it thinks it should have been to begin with (error correction.)

Using an optical cable, the 1's and 0's travel through a true digital medium, and more of them make it across safely, which lets your receiver spend more time on producing the nice rich sound exactly as it was put on the DVD, instead of trying to stitch together a sound that may or may not be as good as what was on the DVD.

Think of it this way: When you call grandma on the phone to say hello, you probably hear grandma pretty well, and she hears you pretty well too. That's an analog connection over copper wires. It sends inexact information, but it works.

Now you sit down at the computer, dial up your ISP w/ your 56k modem, and you either have problems connecting at first and have to try a couple of time, or you're busy online and your modem loses connection. That's digital over copper, and the problems are caused by the interference on the line because the exact information being sent and received is being damaged.

Last edited by renaldow; 12-02-02 at 01:42 PM.
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Old 12-02-02, 02:04 PM
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Uh, renaldow, do you know the frequency/bandwidth that's being transmitted by the analog video signal over component cable? How many times higher is that than the digital audio frequency being transmitted over coax or optical cable?
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Old 12-02-02, 02:08 PM
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As many times as this question has been asked, shouldn't it be in the FAQ along with an answer to cable grading?
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