How to get digital sound? (PC sound card to Logitech Z-680 Digital Theatre system)

Discussion in 'Home Cinema Speakers' started by rollingstone06, Aug 12, 2006.

  1. rollingstone06

    rollingstone06
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    Hey folks,

    My speaker/audio question is coming up! First, my AV background, briefly. I have a 28" Thomson stereo TV, with red and white audio composite at the back which I connect to my Logitech home theatre 5.1 DTS/Dolby Digital/THX control centre's front panel black-coloured jack (see pic #1, bottom right jack). I have 5 speakers (2 front, 2 rear, & centre) and a subwoofer. Since my TV's only stereo, I select Direct Stereo x2 on my Logitech theatre control panel to get some kind of surround sound on my 2 front and 2 rear speakers.

    What I wanna do now is first set up a S-Video connection between my PC and TV so I can play PC games, surf the net, etc. on my TV. But how can I get digi sound? I have a Sound Blaster 2 PCI on my PC. I'm assuming it gives digi output, since I have that yellow composite S/PDIF jack on the expansion slot of my tower drive (see pic #2, centre-right jack), right? On the other expansion slot, there's an orange jack marked "Digital Out" (see pic #3, far-right jack ).

    At the back of my Logitech Z-680, there's Digital (Coax & Optical jacks), and for 6-Channel Direct there's three jacks (Front, Rear, & Central/Sub). I use Optical for my Xbox experience.

    So here goes :lease: :

    1) Which jack, from pics 2 or 3, do I use to get digi output from my PC sound card to my Logitech centre?

    2) What cable do I use for the connection?

    3) Do I connect to Coax on my Logitech centre? (Will I get a surround digi experience?)

    4) A mix AV question. :oops: Pardon it here -- my set-up would be workable, right? i.e. getting digi audio from my PC sound card direct to my Logitech centre, and visuals working separately via the S-Video connection between my PC and TV to play my PC games, surf the net, etc.

    Excuse this long post, and please advise/comment asap, folks...I'd really appreciate the help!!

    Cheers,
    RS :smoke:
     

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  2. Knyght_byte

    Knyght_byte
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    ok, on pic 3 you can use that to get digital output, i dont have any knowledge of pic 2's layout so i wont comment, you need a 3.5mm to single coaxial adaptor cable.....usually its a short male 3.5mm to single female coaxial adaptor, so you need a normal digital coaxial cable (male to male) to plug between the adaptor and the Logitech device....(assuming the logitech has a normal RCA socket for digital input.....

    however, you will only get Dolby Digital passthrough on this for surround sound, or music in stereo sent digitally........you wont get surround sound gaming via this method.....for that you need to use the 3 x analogue outputs (3.5mm to stereo RCA for fronts, another of those for rears and a third for sub/centre) assuming of course the Logitech device does have the right inputs (oh, just thought, the logitech might have 3 x 3.5mm inputs for this like the creative setups do....in which case you need 3 x 3.5mm to 3.5mm cables...)

    as for the AV question, you can indeed send s-video to the TV and have your sound going to the logitech, altho given the stuff involved its possible the two might not sync correctly, but shouldnt be out by more than a few milliseconds...heh

    however be aware that s-video is a poor interface for surfing, if you are talking about connecting to a 28in widescreen CRT TV, then forget it for surfing, gaming wont be too bad, altho any text thats small wont be easy to read either.......
     
  3. rollingstone06

    rollingstone06
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    Hey Knyght_byte,

    Thanks alot for your response!

    Here's a pic of a cable I've used before. For surround sound gaming, is this the cable you're referring to? The second pic is what the back of my Logitech control panel looks like -- from left to right, there's marked COAX, OPTICAL, then 3 jacks marked 6 Ch. direct (green = front; black = rear; yellow = centre/sub).

    If yes, I've connected this cable once before from my SB sound card to my Logitech centre's green, black, and yellow jacks, checked with a cross the digi output box on my Sound Blaster control panel interface from my PC's desktop -- however, I got no sound with my PC games and music. So I unchecked the box, and got a surround-like effect, but I'm assuming it wasn't digi surround sound, but stereo surround sound, right? Am I correct?? And so the alternative is to connect my sound card's Digital Out jack to my Logitech Centre's Coax with the cable you mentioned and get Dolby Digital Passthrough that way without surround sound, right??

    SO:

    1) Is there anyway to get both digi and surround sound?

    2) Which will give me a better gaming and overall TV audio experience, IYO --
    Surround Sound, or the Digital Passthrough method?

    3) Wrt the AV thingy, what's the way to solve the synch. issue?


    Ok, sorry for the long post! Advice, as always, will be great if you can kindly offer it!

    Best wishes,
    RS :)

    PS. You're too right about the surfing thing on my CRT TV. Was difficult to read, although I found that increasing font size helped greatly, although there was still a certain amount of lack of clarity & fuzziness in the viewing experience. Have to say though that TV shows and news media broadcasts were surprisingly clear and almost perfect. :clap:
     

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  4. rollingstone06

    rollingstone06
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    Anyone know?

    Cheers,
    RS :hiya:
     
  5. Knyght_byte

    Knyght_byte
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    ok, heres how it goes.....when you watch a DVD using your computers DVD drive, then you need to have the puter set to output digital 5.1 passthrough.....then use a 3.5mm to female RCA coaxial adaptor out of the orange socket on the back of the actual soundcard...(the 3.5mm end obviously goes in to that), then get a normal digital coaxial cable, plug one end in to the female RCA socket and the other end in to the logitech device....

    this connection will pass digital stereo or 5.1 sound.....


    however, also have that cable you show in your second post with the 3 x 3.5mm connections connected to the soundcard and the logitech device.......these are an analogue connection, but before you think wait a sec, thats not as good as digital, it isnt that simple...heh

    this connection being used means your soundcard is the one doing the digital decoding, not the decoder in the logitech device.......the difference? bugger all......neither are state of the art so the difference is negligable........HOWEVER, you DO need this connection if you want to play games in 5.1 EAX surround modes......you CANNOT play games in 5.1 digital sound through a digital cable because your soundcard does not have digital ENcoding, only DEcoding......there are now soundcards available that ENcode a games sound so it can be sent digitally, but i dont know anyone who has used once yet to say how quick and effecient they are (they need to be quick, otherwise when you shoot someone, they will die before your gun reports the noise of the bullet firing..lol)

    so to summarise, have both digital (single cable) and analogue (the triple cable) connected, when watching DVD's use the digital output box checked, should give you 5.1 (i presume the logitech has a little light or LCD display that tells you if you are currently feeding it a proper Dolby Digital signal yes?), when playing games uncheck the digital box and use the analogue method, if a game has proper EAX surround then you will get full blown 5.1 sound.....if a game doesnt have EAX (or other surround modes) then you can set your Creatives options under CMSS to give a pseudo surround effect.....usually it just duplicates the front stereo to the rear speakers tho...depends what version you have...

    for the synch issue, assuming you having problems with it, i'm not sure, i know you can pick up little magic boxes that solve it when sitting between normal AV equipment.....not sure how it would work between the equipment you have now.......have you actually noticed things not synching up sound to video wise? if you havnt noticed then forget about it, you probably wont...heh
     
  6. rollingstone06

    rollingstone06
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    Hey Knyght!

    Thanks again for the really detailed info...I'll get round to buying the coax adaptor and coax cable soon, and again your post helps so much, mate, so kudos to you since you've totally clarified the audio concepts to me!!

    Cheers and best wishes,
    Stone :thumbsup:

    PS. Re the synch thing, it's not a prob after all -- just a few moments ago, I dragged my TV close up to my computer (cables streched like cooked spaghetti, lol), and connected up the too-short S-Video cable to my TV and the 6 ch-direct cable to my Logitech centre, and it seems that audio-visual is synched perfectly.
     
  7. Knyght_byte

    Knyght_byte
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    you more than welcome mate :)

    glad the synch thing is ok too :)
     

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