Audio connection: RCA vs. fiber optic

 

New member
Username: Alincal

Post Number: 8
Registered: Mar-05
This may be a stupid question, but I'm confused about the audio connections on a home theater. If I use RCA (red and white) cable from my DVD and my HDTV cable box to my AV receiver can I get true 5.1 audio sound or do I need fiber optic cable connections? Is there a audible difference in sound quality? Thanks for any help you can give.
 

Bronze Member
Username: Philman

Richmond, IN USA

Post Number: 73
Registered: Dec-04
Not a stupid question at all, but the best your gonna get from the analog audio (red/white RCA) is stereo and Dolby Prologic.

You must use a digital connection such as COAX (orange) or Fiber to get true digital processing (x.1) capabilities. (Provided your source and receiver are capable.)

 

Silver Member
Username: Paul_ohstbucks

Post Number: 557
Registered: Jan-05
That's not entirely true. You can use a single red or white RCA cable and get true 5.1 surround output providing you connect using the digital coaxial port on your components. Providing it's a well made RCA, it will sound every bit as good as digital coax or optical cables.

The key is making sure your components are 5.1 compat. They both must have either optical or digital coax ports to produce true 5.1 surround.

If you connect using the generic red/white RCA ports, you will only get two-channel prologic as Phil said.

Just for fun(before you blow $100 on a new cable), use a single RCA to connect your DVD player to your receiver using the digital coax port, and see what you think.

Another note....be sure to go into your DVD player setup menu beforehand and make sure you're properly configured for 5.1DD and activate DTS while you're there.
 

Bronze Member
Username: Philman

Richmond, IN USA

Post Number: 74
Registered: Dec-04
I'm gonna come back and agree to a point with Paul. You can use your standard cables for the Coax connection, I merely was pointing out the difference between analog and digital signal sources.

That being said, If your going to try Coax, I would recommend the Yellow (video) wire in the RCA group. The Yellow is almost always a true coaxial cable whereas the red/white could be simple a shielded analog cable. The difference is seen from the higer freq bandwidth the coax provides over the analog cable.

You'll find arguments all over the web on which format to use Coax or TOSLINK (fiber). The basics are the same. Both use Digital (1's and 0's) to transmit all of the sound field data between the DVD and reciever. And while its true, for the most part, noise does not matter on digital signals, bandwidth and frequency rolloff do. When problems occur in digital connections, you dont hear static, you simply begin to loose "parts" of the program material. Will this matter? Maybe maybe not, but you'll never know what your missing. (unless its really bad)

This is my reason to choose a coaxial construction over the others. $100 cable?? I think he must be talking DVI cables for the High def monitor. The Coaxial cable and Toslink fiber can be bought from www.partsexpress.com for less than $10. Walmart has them too, just charges a little more.

my 2¢
 

the Electrical Engineer
Unregistered guest
From my research 5.1 can be achieved with the standard RCA cables through left and right channels, if the receiver supports it of course. The signals transmitted are not single analog signals, they are multiple signals modulated before transmitting then demodulated by the receiver then sent to individual speakers.
I can really tell no sound difference, between the digital method and analog, though it is true that analog transmission is more susceptible to nosie or electro-magnetic interference than digital is. So digital is probably the better choice.

Now as far as what type of cable is best I think this topic is knee deep in horse sh*t!

Optical vs Coax vs RCA, I believe this is a big ploy to make money as usual. Comparing just the cables Optical is hands down the best it is less susceptible to EMI/nosie than a copper gold or silver wire cold ever be and bandwidth is better to, BUT you must look at the application digital transmission 1s or 0s, Digital transmission was basically created inpart to eliminate interference, so an electrical wire would have to have such a tremendous loss to lose that 1 or 0, so save your money and forget that $50 optical cable

Now as far as coax vs RCA cable there could be a very slight difference in resistivity. A 1 or 0 could possibly be lost in transmission, but I highly doubt it I have tried both of these cables and there is no difference that I can hear. What further makes me believe that there is no difference is the way they advertise the coax cable "minimal signal loss for best sound quality" thats the digital processor doing that not the fu*king cable. In the analog world the silver guage wire with gold contacts may play a bigger roll but in the digital world if you have a descent conducting wire such as copper, that 1 or 0 doesnt give a damn. I willing to bet there is no difference between the digital coax and a standard RCA cable for digital transmission! If you want to buy something that might make a difference then buy good speaker wire that is analog transmission.
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