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SB Live and 5.0V on dig. output

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February 18, 2004 12:10:33 PM

i'v read today that digital out on sblive sends 5.0v signal and my reciever (Yamaha 5630RDS) should recieve only 0.5V. how dangerous is this and what to do about it. thanks.

Geronimo

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February 18, 2004 12:54:39 PM

Some sound cards have a jumper others have software control for 0.5 volt/5 volts.

0.5 volt is for COAX.

5.0 volts is for fibreoptic (TOSLINK) signaling.

<b>56K, slow and steady does not win the race on internet!</b>
February 18, 2004 1:07:55 PM

how to check if myne has something like that. i have my sb live connected with my new yamaha reciever and today i accidentaly discowered this about voltages so now i'm concerned because i don't want tu burn my new reciever because of that crap from creative. also if i use analog out on my sb live i suppose i will only have 4ch sound because thats what is writed in manual (SB Live Player 1024). also tell me if i aquire somewhere that additional little board that has real S/PDIF is that proper voltage (0.5) or also 5.0. I read somewhere that it is possible to get the s/Pdif throu the ping on the card. thanks.

Geronimo
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February 18, 2004 2:50:17 PM

Sorry, I can't really offer any SB Live help. I don't own one.

I'm guessing the optical adapter isn't an easy thing to obtain. I would contact Creative Labs if I were you.

Alternatively, if you are in the USA, Radio Shack sells a <A HREF="http://www.radioshack.com/product.asp?catalog_name=CTLG..." target="_new">bidirectional RCA to Toslink converter</A> for about $15. I don't know if it requires 0.5 volt or 5 volts at the RCA connector. I can't find a spec sheet at the Radio Shack site.




<b>56K, slow and steady does not win the race on internet!</b>
February 19, 2004 11:45:48 AM

come on guys is it possible that no one noes enything about this. i men there are thousant people around the world that use this kind of connection and they (my included) are possibly distroyng their equipment. creative should really write this info in their manual or web. do you have some web pages because i only found this info on one page (http://www.ecoustics.com/bbs/messages/1/2098.html). bye.

Geronimo
February 25, 2004 12:35:32 PM

I'm not sure about the Live! cards, but the Audigys send a 2v (just measured it at 1.98v on my card) signal on the digital output which is supposed to be fine for either 0.5v or 5v setups.

*Dual PIII-800 @900 i440BX and Tualeron 1.2 @1.74 i815*
February 27, 2004 4:06:59 AM

It can only encode to 4 channels. So when you play a game you only have 4 channels.

When passing an existing bitstream to an external decoder, the cards encoding capabilities don't matter. Just enable SPDIF and disable AC3 decode. Set DVD player and AC3 Filter to SPDIF.

So you still get 5.1 and 6.1 from DVD's or AC3 sound tracks.
February 27, 2004 2:43:41 PM

Quote:
It can only encode to 4 channels. So when you play a game you only have 4 channels.

That much I understood although I wouldn't call that process "encoding". I would say "decoding to 4 analog channels" as encoding implies you are taking discrete channels, upsampling, and then encoding to digital 5.1, 6.1, or 7.1. At least, that's what encoding means to me and as far as I know only nVidia's nForce & nForce2 can do this.

We still don't have an answer to the original question, is SBlive supplying 5 volts or not at the COAX connector?

<b>56K, slow and steady does not win the race on internet!</b>
February 27, 2004 8:54:58 PM

No I am talking about ENCODING!

When you are using an SPDIF connection to a digital DECODER you card is doing either one of two things.

1) Passing an unmodified bit stream through the SPDIF output. No processing is done. You can only do with with content that is already in DTS or AC3 format. The bit stream is 100% identical to the digital output of a DVD player so the sound is exactly the same. So you always get perfect AC3/DTS 5.1, 6.1 sound from any SPDIF output even if you are using a cheap 2 Channel CMedia card.

2) Processing the audio and encoding an AC3 signal which is sent to the external decoder. Most cards only encode to 2 Channel AC3, some cards can encode to 4 Channel AC3, only 1 card encodes to 5.1 (Nvidia SoundStorm).

Some creative sound cards and speaker combinations have true 6 Channel digital connection. But its done with three 2 channel connections, not one AC3 5.1 signal.

If you don't set things up properly it is easy to accidental decode 5.1 content, downmix to 2 or 4 channels then encode that to AC3 which is sent you your receiver.

If you are not getting the full 5.1, 6.1 EXACTLY as it sound when you use a DVD Player then this is what is happening.

This will happen for example when you forget to disable "AC3 decode" on a SB Live 5.1, or set AC3 Filter to 5.1 rather than SPDIF.

Unfortunately you need an oscilloscope to accurately measure the voltage range of an digital signal. My multimeter just cant handle a voltage that thousands of time a times a second.

I have heard that the SPDIF signal is somehow off on the SB Live 5.1 and some people recommend buying a 3rd party adapter which plugs into the live drive port and provides correct SPDIF output as well as optical out.

The SPDIF FAQ at Doom9 has more info on this.

However I never heard of anyone complaining that their sound card killed their receiver. This is only for people who's receiver has problems decoding the signal.
February 27, 2004 10:41:26 PM

Oops, my mistake. Sorry. Thanks for clearing things up for me.

I was aware that most cards only encode 2 channels and that nVidia Soundstorm encoded to 5.1 (did nVidia ever put out a standalone Soundstorm card?). I wasn't aware that any cards encoded 4 channel sound. Do you know which ones?

I might be able to use such a sound card. I'm still using my old surround system (Marantz SR680 Receiver, NAD amps, and Vandersteen speakers) essentially with only 4 channel sound (no subwoofer, and I use a phantom center channel).



<b>56K, slow and steady does not win the race on internet!</b>
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