Big Picture Big Sound

Why Can't I Get 5.1 Dolby Digital Surround from Blu-ray, HDTV?

By Chris Boylan

Question:

Dear Big Picture Big Sound,

Hi.  I just bought a Samsung Blue ray with the DTS-HD MASTER AUDIO and I have an older receiver that has regular DTS and Dolby Digital. Now when I connect the HDMI cable from Blue Ray to TV (a Samsung LED TV), and the optical output from TV to my receiver, the only sound I get when I play a Blue ray disc is Dolby ProLogic Sound.  It says it is receiving a 2-channel input not 5.1.  Why can't I get regular Dolby Digital 5.1-channel sound?

If u can help me out im going crazy.

-Roberto


Answer:

Dear Roberto,

First of all, there's no "e" in Blu-ray!  But to answer your question, the fiberoptic digital output on most HDTVs will only pass a 5.1-channel Dolby Digital output when you are using the TV's built in ATSC or QAM digital tuner.  If you use an HDMI cable to hook up a source component that outputs DTS or Dolby Digital sound to your HDTV, the TV will convert that internally into stereo sound (for reproduction on its own internal speakers) and then it will output this 2-channel PCM sound through the fiberoptic output.  In some cases, the TV will "tell" the Blu-ray player that it can only accept 2-channel sound but the net effect is the same - only 2-channel sound from the fiberoptic output.

Analog and Fiberoptic Digital Outputs
The fiberoptic digital output on most TVs will only output a 5.1 channel signal when using the TV's built in ATSC or QAM tuner.
I've seen some recent model VIZIO TVs that actually have an option in the set-up menu that allows you to pass a Dolby Digital 5.1 channel bitstream out through the fiberoptic outputs but I've yet to see this feature on other brands.  Of course, this is only a partial solution as you still need to be able to pass through DTS 5.1-channel surround sound to your receiver as well.

Your best option is to use the fiberoptic or coax digital audio output of your Blu-ray player connected directly to your receiver.  Your TV should still get 2-channel sound via the HDMI connection so the TV speakers will work, but your receiver will get a 5.1-channel Dolby Digital or DTS soundtrack from DVDs and Blu-ray Discs.  For those Blu-ray Discs that have a multi-channel PCM soundtrack (of which there are only a few dozen in existence), you will get 2-channel PCM from the S/PDIF fiber or coax digital outputs, but you will get discrete 5.1 channel sound from any DTS, DTS-HD, Dolby Digital or Dolby TrueHD disc.

I hope that helps, and if you have additional questions about configuration or player settings, please post them over in our forum for a response.

Regards,

-Chris

Keep those cards and letters coming! if you have a question for one of our home theater experts, shoot us an e-mail to "Ask The Expert." We'll select among these for future installments in this column. Due to the volume of requests we receive, we cannot reply to each question personally.

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