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Mini-jack to RCA cable can send digital 5.1 sound?

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May 15, 2004 10:08:41 PM

Sound Card: Creative Sound Blaster Audigy(1) Gamer
5.1 HT system: Yamaha HTR-5730 receiver w/ Athena Micra 6 speakers

I can see the "digital out" on the back of my sound card, but it's a mini (3.5mm?) jack, not coaxial or optical like MOST digital outputs... Now, I hear you can use a simple "mini-jack to RCA" cable to get digital sound to your receiver, BUT I heard from another source that RCA is only capable of analog, so... WTF?

The only RCA jack on my receiver (and most others I'm sure) is for the sub-woofer. So, that would mean that the RCA cable would have to be plugged into the coaxial input to get digital sound from it. That doesn't sound right...

IF RCA is really capable of sending a digital 5.1 signal, then why do people spend more on buying a coaxial cable to hook up a DVD player to their receiver. Why not use a cheaper RCA cable and just plug it into the coaxial jacks??

Ya Savvy?
May 17, 2004 4:52:50 AM

Yes. No. Wow, OK, first thing is, I believe a standard monural minijack to RCA adapter will work...but it seems like Creative would have included one with your card. In fact, damn Creative for not simply putting the RCA jack there in the first place! Anyway, there are "two kinds" of digital connectors for home stereos: "digital optical" and "digital coaxial". Digital Coaxial is called S/P-DIF in the computer industry (audio enthusiast aren't smart enough to use that term), it means Sony/Phillips Digital InterFace. When you say most stereos don't have them, you're right, most stereos don't have either digital coaxial or digital optical connectors.

Anyway, I've heard you need special high quality cables for digital coaxial, but they DO use RCA connectors, and let me tell you something, some of these old school "analog" RCA cables are extremely high quality, HiFi has been around forever (or at least since the 60's)! So I don't know what they're getting at when they talk about quality being the issue!

MOST GOOD RECIEVERS have MANY RCA JACKS. If yours doesn't have a digital coaxial input, you might be stuck.

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May 17, 2004 7:34:27 PM

I won't pretend to be an expert on this (far from it) but I recommend video cables vs audio cables as substitues for coax digital cables.

It is my understanding the issue is all about termination. Coax digital (and composite video) cables use 75 ohm termination. RCA audio cables are specified to be 50 ohm but can be anything since even fairly large variances don't affect audio frequencies. However for digital the wrong impedence can greatly affect things. Use the wrong impedence and you get reflections along the cable. This causes errors. How severe? I can't say.

Regardless, since video cables have the correct impedence and they are so cheap why use audio cables?

<b>56K, slow and steady does not win the race on internet!</b>
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May 17, 2004 10:38:24 PM

Thanx for the help guys.

I learned a LOT about RCA cables since I posted this topic, most of it really suprised me too. I was a little confused earlier about what exactly an RCA cable is. I thought the single prong RCA cables and the 2/3 prong analog/composite video cables were totally different connections, but they're all the same thing with MAYBE slight differences (like the ohm).

Anyway, I tested about 3 different RCA cables running from the digital out on my sound card (with a mini-jack to RCA adapter) to the coaxial digital input on my receiver, and they ALL gave me 5.1 digital sound! Now, supposedly, while all RCA cables should work, you may not be getting all the frequencies from lower quality ones. It's safest to go with a 75 ohm RCA, which coaxial and composite video cables are by default (like what phsstpok wrote).

So... unless you have a $2000+ HT system, DON'T WASTE YOUR MONEY ON A COAXIAL CABLE. You'd be hard pressed to notice the difference between the digital sound coming from a coaxial cable and a composite video cable. Strange how this isn't common knowledge eh? It's aalll marketing...

P.S. for those of you who tried getting your Creative sound card to output a digital signal to your HT receiver and didn't get the results you expected, this is for you. Apparently, you'll only get full, REAL use of the 5.1 channels (or higher) while playing a DVD or AC3 movie. If you stop or even just PAUSE the movie, you'll lose true 5.1 sound and just get plain stereo, meaning you will NOT get 5.1 sound in games. Most receivers can SIMULATE 5.1 from a stereo sound (Pro Logic I/II), but it won't produce the 3D positional audio we all want from games. However, if your receiver has discrete 6CH input jacks, then you should be able to hook up your Creative card using three seperate mini-jack to Y RCA cables. This will give you ANALOG 5.1 sound, which is definetly not as clean as digital 5.1, but you'll at least get true 3D postional audio in games (that support EAX).

Unfortunately, I find that using an analog connection from my PC to receiver produces a very noticeable "hiss" noise, which, with a digital connection, is non-existent. If anybody knows a good method of reducing this noise I would really appreciate the advice.
Thanks

Damn... I typed that much???
May 17, 2004 10:52:54 PM

I thought hiss/noise/pops/clicks were all part of Creative's "superior" technology?

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May 18, 2004 3:18:29 AM

Hiss? One quick thing to check. In your sound controls make sure the record controls for microphone, line-in, and any other input device are muted when you are not actually using those inputs. The noise floor for those devices can be amplified during playback producing hiss even if you are NOT RECORDING.

Another way to reduce hiss with soundcards is to keep the Windows volume low and use your speakers (or your Receiver) to compensate.

Unfortunately, some programs control Windows master volume instead of the playback device volume. This results in very startling moments if you have the gain on your speakers or receiver really high.

As for digital 5.1 output with games, currently only nForce2 motherboards with Soundstorm can do 5.1 encoding (Dolby Digital).

Soundstorm PCI soundcards were once rumored but I've never seen one.

<b>56K, slow and steady does not win the race on internet!</b>
May 18, 2004 7:20:54 AM

2 red Unfortunately, I find that using an analog connection from my PC to receiver produces a very noticeable "hiss" noise, which, with a digital connection, is non-existent.

When you are using the analog outs on your pc card you are using the DACs on the card, when you use the digital out on the card you are then using the dacs on the receiver. The dacs on your receiver will be of a higher quality than the one on your card. Aside from that the big difference is when you use an internal sound card, you pick up internal noise from all the internal electronics in your computer they only way to bypass that, aside from the things that were already mentioned, would be to get an external sound card or continue using the digital out.
May 27, 2004 2:06:34 AM

People tend to confuse wire types and jack types.

RCA is a kind of jack on the end of a wire. The wire could be coax, flat, twisted pair, or whatever.

The reason a regular wire with RCA jacks works is because the creative cards actually output their digital signal at 2v, instead of the 0.5v that most equipment uses. For short distances regular wire will work fine.

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Anonymous
September 20, 2009 12:02:21 PM

One simple tip to remove the Hiss noise, just take a head-cutted metal wire and put it under a screw anywhere on your computer, then do the same thing with the other cutted head of the wire and put it under a screw on the reveiver. it is called ground noise. i had to do this a lot of times back in 80's with turntables and stuff.

BTW. I Tested it and it worked using a rca jack and a JVC Receiver.
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