Many of our customers ask us how to get surround sound playback on their home
theater systems from DVD movies playing on their computers. Here's an overview
of the process and how to hook it up: 

What Do I Need? 
  - Software DVD movie player on the computer (e.g. WinDVD, PowerDVD, MyDVD,
    etc.) 

  - Soundcard with optical digital output (S/PDIF with TOSLINK connectors)

  - Windows 2000, XP or later, running on a reasonably fast computer (1.8 GHz 
    or faster recommended) equipped with a suitable video card (AGP or PCIe) 

  - TOSLINK optical cable 

  - Home theater receiver with Dolby Digital/DTS decoder circuit and outputs
    for surround-sound speaker setup

Some Basic Concepts: 
  - "AC3" is any Dolby Digital or DTS surround sound "data stream."

  - The industry standard frequency for AC3 / Dolby Digital and DTS is 48kHz
    and higher rates are PCM data (2-Channel Audio). You might be able to 
    achieve multi-channel in the 96kHz rate by using "HDMI" Output but this
    impractical, expensive as well as the Software required to process it. 

  - "S/PDIF" (Sony/Philips Digital Interface) is the standard format for
    sending digital audio data between devices. A soundcard's "Digital Out" is
    the same as its "S/PDIF Out." 

  - The AC3 data has the 6 or 8 channels of surround audio information ENCODED
    onto a two-channel (stereo) data stream. This surround data needs to be
    *DECODED* into multiple channels. That is why a "Dolby Decoder" is 
    *required*. 

  - The soundcard does not have a decoder built-in. When you play the DVD
    movie in your computer, you may choose to have the surround data decoded
    by the software DVD player, in which case the multiple channels will be 
    sent to the multiple ANALOG outputs of your Turtle Beach soundcard. For 
    PCI soundcards, the analog outputs are color-coded as follows: 

        GREEN – Front L/R
        BLACK – Surround L/R
        ORANGE – Center/Subwoofer
        ORANGE (1) – Rear L/R (for 7.1 only)

  - You may also choose to have the AC3 encoded audio data sent out through 
    the soundcard's Digital Out. This process is called "AC3 Pass-Thru"
    because you are sending the surround audio data out of the computer, 
    unchanged from the way it is encoded on the DVD (it is just "passed
    through" to the receiver/decoder). 

  - Remember that the AC3 audio data needs to be decoded into the multiple
    channels. So what does the DECODING? In this case, your home theater 
    receiver must do the decoding. After decoding, the receiver will have 6 
    separate channels of audio it can convert to analog, amplify and then play
    through your six-speaker surround setup. 

  - How do you hook this up? It's very simple:
    1. Take a TOSLINK optical digital cable (available from Turtle Beach or 
       from most electronics stores), insert one end into the Digital Out 
       from the soundcard, and the other end into the Digital In on your home
       theater receiver. 
    2. Insert the DVD movie disc into your DVD drive. 
    3. Start your software DVD movie player. 
    4. Set the software DVD movie player to send audio to the Digital Out
      (S/PDIF Out). 

   - The receiver should detect an incoming Dolby Digital or DTS data stream. 

NOTE 1: 
   Many people purchase self-contained surround sound speaker setups. Most of
   these do not contain the necessary DECODING circuitry, instead relying on 
   the source (the computer) to do the decoding. With speaker setups like
   these, you will need to use the ANALOG outputs of the soundcard. 

NOTE 2: 
   The AA SRM has a true surround sound analog output on a 9-pin DIN 
   connector. This is designed for true 6-speaker playback when used with 
   surround sound headphones like our EarForce HPA2 and X52. The AA Micro 
   and AA Amigo have optical digital outputs and can perform AC3 Pass-Thru, 
   but they have stereo (2-channel) analog outputs only.
______________________________________________________________________________