Digital Output through RCA cables, problems...

[wetcat007]

I have a problem when running a digital audio signal from my computer to my reciever through RCA cable instead of coax, whenever their is any lightning or a floresent light is turned on/off or a tv, is turned on/off, microwave and other things, the signal drops for a second or more. Does anyone know what could be causing this?

 

[Matthias99]

Um, because you're using crap RCA cables instead of real coax?

Edit: And/or your house's wiring sucks.

 

[drag]

You want to use as short as a cable as possible.

Also isolate it from other cables to try to stop crosstalk. Like if the wire is resting on, around, or routed parrallel to a power cable then that's a bad thing. If the wire has to cross a power cable make sure that it is at a 90 degree angles to avoid crosstalk.

If non of that works, try to get a higher quality cable. Also the problem may not be with your cable, but with the stereo equipment and interference. You can buy isolators/power filters to try to keep noise out of your equipment from the power lines.

Um, because you're using crap RCA cables instead of real coax?

Edit: And/or your house's wiring sucks

Personally I am curious. What exactly is the differences between Coax cable and regular RCA A/V cable?

 

[GoSharks]

for digital coax out, the cable should be 75ohms. RCA video (the yellow one) fits that specification and should work in a pinch. however, the audio cables (red, white) are not 75 ohms and will not give good results.

 

[drag]

Originally posted by: GOSHARKS
for digital coax out, the cable should be 75ohms. RCA video (the yellow one) fits that specification and should work in a pinch. however, the audio cables (red, white) are not 75 ohms and will not give good results.

RCA video is 70ohms.
Close enough for government work.

But even then audio cables are good enough (most of them are the same stuff as video lines, it's cheaper to make 1 cable and give them 2 different colors, then it is to make 2 different types of cables.)

The only time it's realy critical for the type of cables is if your using "phono" connections or doing video connections. Also maybe subwoofer since those lines carry more power and tend to be much longer then cables normally used for going from spdif to spdif connection.

I doubt that that would cause the interference just on the type of cable alone, though. Unless the cables were absurdly long.

 

[beatle]

Originally posted by: drag
Personally I am curious. What exactly is the differences between Coax cable and regular RCA A/V cable?

Regular RCA a/v cables are twisted, coax is not.

Some good info on patch cables on Ars.

I use RG6 coax (like what you hook your cable modem up with) w/F to RCA adapters for my sub. I use a cheap toslink cable to connect the PS2 to the receiver. I'm not a fan of expensive cables.

For the OP: audio cables aren't always interchangable with digital audio cables. You need a 75 ohm cable. Many analog audio cables aren't 75 ohm

 

[imported_rustybx]

I would bet you have a ground loop. Unless the RCA is damaged it's unlikely to be the culprit.

Connect computer/monitor and receiver into same power outlet/surge suppressor. Disconnect all other possible paths (cable modem, lan, printer, etc). Turn the offending light on/off. If the problem still occurs the receiver is the likely culprit. Also could be damaged RCA or extremely poor house wiring (unlikely). If the problem goes away you have a ground loop. Easiest solution is use an optical connection.

 

[imported_rustybx]

There's no such thing as a 75 ohm RCA patch cord. The conductor can be 75 ohms but the terminal can't. The dimensions of the center pin make 75 ohms impossible. Most terminals are 25 ohms...even Canare terminals (widely regarded as the best) don't exceed 40-50 ohms which is very near the theoretical maximum impedance for the RCA geometry. Even with the best quad shielded RG11 coax there will be refections due to the impedance mismatch - VWSR about 1.1 at 200MHz. Therefore, RCA is limited to about a few hundred MHz....which is at least an order of magnitude greater than these lowly S/PDIF signals. As long as the equipment is reasonably designed just about any old crappy cable should work fine.

 

[wetcat007]

Originally posted by: rustybx
I would bet you have a ground loop. Unless the RCA is damaged it's unlikely to be the culprit.

Connect computer/monitor and receiver into same power outlet/surge suppressor. Disconnect all other possible paths (cable modem, lan, printer, etc). Turn the offending light on/off. If the problem still occurs the receiver is the likely culprit. Also could be damaged RCA or extremely poor house wiring (unlikely). If the problem goes away you have a ground loop. Easiest solution is use an optical connection.

Well in this house i wouldn't rule out poor wirring as it's a fact.. lol, but this happens, with lightning and other stuff to outside of the house. I'm using some pretty heavy gauge RCA cable, but you guys seem to think that a coax wire would work better? If optical cablkes werent so damn expensive I'd go ahead and use that, since that eliminates the problems, but my opitcal cables are all too short. So I should somehow us coax cable, to do this? Right now I'm uing a radioshack adaptor to change optical to rca output, and this happens on any device when I hook it up using rca with or without the adaptor piece so that's not the culprit, what would I do to get it hooked up through a coax tv line?

 

[wetcat007]

Originally posted by: GOSHARKS
for digital coax out, the cable should be 75ohms. RCA video (the yellow one) fits that specification and should work in a pinch. however, the audio cables (red, white) are not 75 ohms and will not give good results.

Oh... there's a difference between the colors other than to just identify them? lol i never knew that.