Digital Coaxial vs. RCA?

[awdio]

an "rca" cable is a coax cable. Cables do make a difference and they sound different from one another. If the cable designer meant for the cable to be used as a digital cable then it stands to reason that it should work well in that capacity but not always. Any cable can be used as a digital cable and it might sound good or not!

 

[markw]

Aw, gee. Really?

an "rca" cable is a coax cable.!

You should have left it at that. But, to be a nit-picker, there is no such thing "RCA cable". . RCA is a connector type, not a cable type. To be more exact, you are describinga coaxial cable with RCA plugs on the ends. And, even moreso, depending on it's usage it can be anywhere between 50 and 110 ohms and still work.

Cables do make a difference and they sound different from one another.!

Really? Many, many listening tests have proven otherwise. ...particularly when the subject didn't know what was being tested. Again we're still waiting for some real proof of your definitive and sweeping statement.

If the cable designer meant for the cable to be used as a digital cable then it stands to reason that it should work well in that capacity but not always.!

And, pray tell, when would they not work adequately? Actually, if he designed it to be a "digital" cable it dang well BETTER work in that capacity... always. Right? But, I'd say it's a safe bet it will work. After all, if a coathanger worked fine, how off could his official digital design be to not work?

Any cable can be used as a digital cable and it might sound good or not!

Really? I'm using 20 year old audio interconnects for my system here and they worked just a well as a gen-yoo-wine o-fficial "digital" cable. I tried one, heard no difference and went and got my $$ back. And, it's a lot easier to manipulate than a coathanger.

 

[shokhead]

an "rca" cable is a coax cable. Cables do make a difference and they sound different from one another. If the cable designer meant for the cable to be used as a digital cable then it stands to reason that it should work well in that capacity but not always. Any cable can be used as a digital cable and it might sound good or not!

Digital! What an $$$ word. I bet the electronic's big names love it. It might be there fav word. I would say Digital is thrown around more then a baseball. If its Dig,it best be better.

 

[jaxvon]

Amen to that. I just picked up 50ft of 14ga speaker wire at HD (instant gratification, couldn't wait for westlake) and it's some RCA brand stuff. Sure is pretty, but all over it's labeled as "Digital" speaker cable. I dunno about the rest of you, but a square wave isn't that sexy of a sound. I'm not sure if I want digital speakers.

 

[Privateer]

an "rca" cable is a coax cable.

Wrong again buddy.

 

[BoilerTipp87]

Okay guys, I just got done reading through this topic thread and got something for you all to ponder and hopefully give me a reasonable answer.

I just bought a new computer that has digital coaxial out. However, my stereo system only has digital optical in. I was able to buy an adapter at Frye's electronics for $18 that converts digital coaxial to digital optical (model number of converteer POF-820, google it if you want to know what it is). So I am hooking my computer up to my stereo system, and I run into many problems with just regular "rca" cables. First I use an old mono cable I had, I get no sound at all. Second, I use an a beefy stereo cable that is about 20 ft long (rca), and I get only Linear PCM on my stereo. I try not as of a long cable, and also not as thick, and I get a in and out dolby signal (no Linear PCM at all). I do not know the resistance on any of the wires either, so I don't know if it is in the 70ish range. So I am just really confused on this whole situation. Any input anybody?

So tomorrow I am going to go to the store and purchase a digital coaxial cable. I am hoping that it works, because I really want the 5.1 surround out of my computer. But what it sounds like from the talk on this forum, that it shouldn't make a difference. It could because of the converter, but because I was getting such mixed results, it seems like it has more to do with the cables than the converter.

After I wrote this, I have another interesting development, I have three different frequencies for my output, a setting I can change on the computer. These frequencies are 44.1, 48, 96. If I use 48 I get pure Linear PCM signal on my receiver. If I try to use 96, I get the in and out digital light on the receiver. Just more thoughts, sorry everybody if I sould like an idiot, I am learning about this on the fly.

 

[BoilerTipp87]

ok everybody, I think I really am an idiot. Nothing was wrong with my connections at all. It was my understanding of what should be dolby digital and what shouldn't and that my receiver or the cables don't take frequencies of 96 khz. I was for some reason expecting dolby digital all the time. So, I tested a movie with dolby digital and the input on the reciever changed to digital and the audio sounded exactly the same as being played on a dvd player. Anyway, sorry to waste all your time by reading my posts. Maybe somebod will have the same problem later on and my ridicilous posts will help them.

 

[jaxvon]

Heh, it's okay. At least you fixed the problem quickly.

 

[markw]

No problem. Good troubleshooting.

I was for some reason expecting dolby digital all the time. So, I tested a movie with dolby digital and the input on the reciever changed to digital and the audio sounded exactly the same as being played on a dvd player.

We have all been there. I still hold my breath when I pop in a movie and it starts out showing DPL and only switches to Dolby Digital when the feature itself starts.

So, what cable did you wind up using?

 

[supatrukka]

Digital Coaxial vs. RCA

Greetings all,

I have just finished reading this thread and thought I might offer my two bobs worth, just incase any one may be interested.

It seems to me that some sound like they know what they are on about, and others are new to the whole audio thing, either way, we should never be too old to learn new things.

The other thing, if any out there is like me, we like to know why or why not, not just what will or won't work. So here's some thoughts for you to ponder.

The first point that needs to be made is that the RCA in RCA cable refers to the connectors at the end, NOT the cable.

Second, the Digital in Digital Coaxial Cable is kind of pointless and more of a sales feature than anything of real use. Why? Quite simply, any cable can handle a digital signal. In simple terms, this digital signal is required by a digital amplifer to tell it where to send the sounds. The digital signal comes from the digital output from your digital source (dvd player for example). The old analogue signal system, uses a voltage running through the cable and varies the strength or power of that voltage. With digital, the voltage is either on or off (albeit many thousands even millions of times a second). In both cases, the same cable can handle either signal. So whether it is a $100 yoo bewt special doo dah cable or a coat hanger. In basic principle it doesn't matter. The digital signal from the dvd player will get to the digital amp so long as there is a connection between the two.

Three, the Coaxial bit in Coaxial cable refers to the type of actual cable used. If you look at the rear of your dvd player or amp, if there is a coaxial connector on the back, there is a good chance it will have COAXIAL printed either above or below the connector. This is printed there for a reason. It is to tell the user that a coaxial cable is the preferred cable type. Note that I did not say ONLY cable type. As mentioned before, in basic principle, a coat hanger will infact pass the signal from one to the other. A proper coaxial cable how ever will do it much better, and by better I am referring to signal quality.
For an exploded diagram of a coax cable go here:

http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci344289,00.html

For an excellent description go here:

http://en.wikipedia.org/wiki/Coax

The main reason for using coax cable is because of the cables ability to block anything that may interfere with the signal between the two units and degrade it some how. This interference can be caused by simply running your signal cable next to the power cables of the same devices. By nature, power cables radiate their own signal, this radiated signal can interfere with the signal running from your dvd player to amplifier, and will in many cases cause that signal to be of lesser quality than it should be. This in turn could cause your amplifer to send the wrong sound to the wrong speaker, could caused a crackling, hissing or humming sound, or simply just not sound quite right. Or you may not hear anything at all. It should be noted that this interference is more typical in longer cables of say 3 metres and up.

So, should you spend the $$$'s on a yoo-bewt sooped up cable? No. not necessarily. But ask yourself this, why did you by a digital surround amplifier and dvd player? If you're like me, it's so you can experience the awesomeness of home theatre. True? If yes, then either buy or make your own cable that has rca connectors (plugs) at the ends, so you can connect it to your dvd players and amps connections and use some type of reasonable (not soopa doopa) quality coax for the cable, to stop the signal from being interfered with from outside sources. Give your senses the best chance of experiencing home theatre the way it should sound.

It is important to note that RCA type cables are not always made with coax quality cable, double check for yourself or get the sales person to show you.

Oh, and as for gold connectors, don't waste your money, it's just a wank factor that you don't need. You nor I will tell the difference between gold connectors and plain ones.

I hope I didn't waffle on too much and you have more of an idea of why the correct cable is important. Correct cable doesn't mean $$$'s, it just means correct specs. RCA connectors (plugs) and coax cable.

Happy home theatre-ing to all.

Keep it real.

 

[MDS]

The old analogue signal system, uses a voltage running through the cable and varies the strength or power of that voltage. With digital, the voltage is either on or off (albeit many thousands even millions of times a second). In both cases, the same cable can handle either signal.

All good points in your post but just to clarify, digital transmission is not necessarily on and off - that is a common oversimplification. It depends on the modulation scheme being used. S/PDIF uses NRZ (non return to zero) and bi-phase mark as the modulation scheme. So a logical zero could be +1 volt and a logical 1 could be +5 volts.

 

[mtrycrafts]

Once again I have to laugh at the coat hanger thingie...

I've yet to walk into anyone's place, being private or an audio business and have someone say....

Hey lookie here!! I saved zillions by using coat hangers over Monster! Just listen to this thing rock!!!

LOL

Is there an implication here that a coat hanger would not work?

Of course no one uses it. They are not saving zillions and good cable is inexpensive and much easier to deal with

 

[supatrukka]

All good points in your post but just to clarify, digital transmission is not necessarily on and off - that is a common oversimplification. It depends on the modulation scheme being used. S/PDIF uses NRZ (non return to zero) and bi-phase mark as the modulation scheme. So a logical zero could be +1 volt and a logical 1 could be +5 volts.

Thanks MDS for your reply.

I was trying to keep things as simple as possible for the sake of the newbies. Many times I see/hear experienced people explain things to newbies, and when they are done, they newbie is left with a puzzled looked thinking "huh, what the heck was all that about, all I wanted to know was......", so I try and explain things as simple as possible. "My dad used to call it 'learning to talk in dumb peoples terms'". That said, thanks for your clarification.

Cheers

It is a sad day when we can no longer be taught something new.

 

[BostonMark]

But has anyone tried hanging their suits on Monster Cable? It keeps the shoulders from getting mishapen and frayed.

 

[thisiscmd]

Interesting Tid Bit...

Just breezing over some posts I've read. Lot's of good information. It should be stressed though, with digital its not a situation where you get it or you don't. Isn't a digital signal which ideally looks to cut straight up instantaneously from 0 to 1 actually doesn't? Furthermore, isn't this signal actually a combination of different harmonics, which imply different frequencies? Therefore, certain frequencies, based on the construction of the cable, could lose a lot of integrity over the lenth of the cable. Therefore its not like you will result in all 0.9s and 0s instead of 1s and zeroes. You may actually get a 1 where there is supposed to be a zero, or vice versa.

Furthermore, I have read someone say that coat hangers could be used if you could block unwanted outside emissions. Well if you have too much distance between your signal line and your return line, in other words you just hold the 2 coat hangers apart so they don't touch, you end up with parasitic inductance. Which, especially for high frequencies, results in impedance and therefore signal degredation.

Could be wrong who knows....

 

[jaxvon]

I believe a digital signal has a carrier signal and the 1s and 0s are modulated over this signal.

 

[cayvman]

coax for video

So, in case anyone is still reading and commenting on this thread, if I have a coax IN for video on my av unit and a coax OUT on my dvd unit, can I use a "digital" coax cable with (useless?) gold RCA connectors that was labeled by the manufacturer for audio (assume it's rated at 75 ohms)? Will I be missing or losing any signal?

 

[MDS]

So, in case anyone is still reading and commenting on this thread, if I have a coax IN for video on my av unit and a coax OUT on my dvd unit, can I use a "digital" coax cable with (useless?) gold RCA connectors that was labeled by the manufacturer for audio (assume it's rated at 75 ohms)? Will I be missing or losing any signal?

If the characteristic impedance of the cable is 75 Ohm you can use it for composite video, digital audio, or analog audio regardless of the color of the jacket or connector or how it was labeled by the maufacturer.

 

[cayvman]

Thanks for the quick reply.

 

[3beanlimit]

Is there an implication here that a coat hanger would not work?

Of course no one uses it. They are not saving zillions and good cable is inexpensive and much easier to deal with

No...there is no implication that it wouldn't work.....it's just that you and a couple of others LOVE to throw that in the argument all the time but I'd bet a bag of donuts you've never tried it and the reality is...you'd never use one.