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Atleast in the computer world - digital data is either "on" or "off". You either get your data or you don't.


Does this also transfer to the a/v Home Theatre world when you are dealing with digital connections?


IE If I use a Digital Connection via an RCA Cable directly to my receiver does the Quality of that RCA Cable matter? (Provided ofcourse it receives the signal).


What about Toslink Digital Cable?


Also do you know about DVI? Is DVI "On" or "Off" as well?


Thanks,

Russ



P.S. I'm sure this has been answered in the past, I tried to search the boards but since my search words were Digital & Cable I didn't exactly get the results I wanted :p
 

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Theoretically the quality of the cable wouldn't really matter (for any digital connection) because, as you said, either the signals there or it isn't, there isn't any information carried on the signal.


That said there is a limit to the construction quality that I would deem acceptible. Many inexpensive optical cables (even stuff from well known cable companies) is rather poorly constructed and could develop breaks and connector problems if not handled delicately.


This is one of the reasons that most people recommend going with coaxial digital cables, they are much more resilient. However, they are still a metal conductor and thus are succeptible to RF and other forms of interference. Something for $30-40 from Radio Shack or bettercables.com should work just fine. If you are makeing runs of considerable distance (50 feet or more) or live in an area with significant interference problems then consider going with something of better quality.


DVI is a coaxial digital connection.
 

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Actually, in the 'computer world' you always get data. It is just a matter of wheter it is a 0 or a 1. There is inherent error detection built in. Usually, anything lower than or equal to .3 is considered 0. All others are considered 1. There is also the matter of when and how long it takes to go from 0 to 1. It is NOT instantaneous. If the sampling happens in the state of flux between 0 and 1, you get something in the middle (since it is actually measuring microscopic voltages.


The issue of a quality cable has to do with less distortion of the signal, less impedance, and how fast the cable can pass on the signal from end to end. Granted, in the audio world, distances are relatively short. In theory optical is a better medium for transmission - in a perfect world. Our living rooms with cheap connections and cables is hardly perfect.
 

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Digital signals are less subseptible to exterior noise influence. Especially infrared transmission used with toslink connections. However, get those IR cables bent or exterior light and heat around them and you are asking for problems.


Distance is more of the enemy with digital signals. If the digital cables are let's say under 50 ft, I'd say you would be ok.


Before unshielded twisted pair (UTP) cabling became very popular, computers were networking with 10MB/s on 50 ohms coaxial cable called 10base2 or 10base5 and they covered some good distance.


In summary, digital is more forgiving of cable imperfections because the electronics typically triggers during the high-low and low-high slope of the signal.
 

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It doesn't matter nearly as much as with an analog signal. My theory is, with digital, the sound is either there, or it isn't. If you are getting a lot of interference, you might get errors, just like a scratch on a CD or something, you will hear a pop, or maybe a squeak sound, depending on the DAC used, and how well it corrects errors.


So, if you are not hearing imperfections, like squeaks or pops as I described, then a $10,000 cable will make absolutely no difference at all in the sound.
 

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it depends on how revealing your stereo system is, and how good your hearing is. some people really cannot hear the difference, some can. i would say unless your system is very high resolution, it won't matter a whole lot. but it does not cost a lot to use one of the best digital cables available - just get a good coaxial video cable using Canare RCA plugs and good Belden (1506A or 1694A) or Canare (L5CFB) coax, and you will have one of the best digital cables money can buy, for all of $20.


i prefer coaxial to toslink optical, but it depends on the gear you're using - some products may sound better with one or the other. if you go Toslink, Monster Interlink 100 toslink works fine and is not expensive. but it's not as durable as coax as others have noted.


my friend, who is a very scientific-minded guy, would not believe that digital cables could make any difference in sound quality. so i switched digital cables in my system while he was listening, and he instantly noticed how it messed up the sound - soft, muted, and too laid-back for his taste. he was dumbfounded, but couldn't deny what he heard. interestingly, the cable he didn't like was an esoteric $500 "audiophile" cable, while the one he liked was my homemade $15 Belden/Canare cable.
 

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Is monster interlink 100 plastic fiber or glass fiber. how do I find out if it is glass fiber. I searched the net and none of the ads say anything about plastic or glass fiber and none mention the bandwidth of the cable. I feel

all this expensive toslink cables are just a scam. If they are really superior

why dont they mention the bandwidth. why is that a secret.
 

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i'm pretty sure monster interlink is plastic fiber. it would probably cost much more if it were glass...


i'm not sure what you mean by the "bandwidth" of a toslink cable. i suppose there is a maximum pulse rate that a given optical cable can transfer reliably, but i've never seen it rated before... the toslink specification is very low bandwidth anyway (i think under 10Mbps).


i have heard some differences between toslink cables, but i haven't compared a whole lot. in general interlink 100 works quite well, sounding a bit more transparent than a cheaper generic cable, and i see little reason to spend much more. one piece of advice i do have - get at least a 3m length, the longer the better up to several meters at least. it helps reduce interference from reflections etc., and sounds better. lest you think this be voodoo, i got this advice from a very experienced and savvy telecom engineer.
 

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The general consensus of this thread has been what I have found as well, that quality does still matter to a degree, but not as much as with analog connections, as digital connections have a certain amount of error correction built in to help minimize interference and noise.


There is another great thread in this forum (actually in this section of the forum) about the differences between coax and optical digital connections, suffice it to say, that in most cases, due to a number of factors (bad quality fibers, loose connections, bad RTX decoding) coax digital seems to give you better sound for less money, unless you are experiencing ground loop issues (in which case you have to go balanced digital (expensive and not on most equipment) or optical). Other problem with optical is that if you step on your cable on a hard surface (doh!) you can break the fibers and go have to buy a new one :)


Monster Interlink 100 is plastic I am pretty sure, but as you move up it might eventually become glass (or better plastic) aside from the actual material of the toslink cable the connection plays a big role, poorly designed connectors on the cable (or the device) can lead to refraction and light leakage at the cable termination point, which is bad for your signal.
 

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the error correction of digital connections doesn't really have much to do with anything, as it would take a LOT of signal degradation and interference to come anywhere near inducing an error in a digital interface - to get a logical 1 or 0 to be misinterpretted would involve signal loss to the point where the transmisison would be barely usable anyway. it's the inherent nature of the digital signal of course that is really responsible for its robustness - the discrete data states as opposed to the infinite variations of an analog signal which are subject to myriad linear and non-linear transformations due to unavoidable physical phenomena. simply put, data corruption is easy to avoid with digital, hard with analog.


yes, coax digital often will sound better than toslink, and there is a very simple reason for this. measure the induced jitter of your average toslink connection vs. a decently implemented coaxial link, and more often than not the toslink will have much higher measured jitter. toslink quite simply is a very poor transport for a high speed serial asynchronous signal like digital audio. that said, some gear (often cheap gear) will actually sound better with the toslink connection than with coax. this is most likely due to a very poorly implemented coaxial line driver/receiver circuit, and/or electrical interaction (e.g. ground loop/noise) between source and load components which can induce jitter in the circuits at either end. optical does have the benefit of strict isolation between components.
 
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