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    Question about TV audio

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    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Question about TV audio

    Post by Dave_in_Va on Wed Jul 24, 2013 4:36 pm

    I apologize it this is too far off-topic.

    I just hooked up a V-DAC II to my HD television. I had been using a Yamaha home theater amp which I hated because I couldn't figure out all of that "scene" stuff. I preferred to use my old Pioneer SA 520.

    I have a Roku, a DVD player and a BluRay player connected to the TV via HDMI. The digital audio out of the TV is into the digital in of the V-DAC, RCA out into the aux. in of the Pioneer.

    The Roku, the Oppo DVD player and the Panasonic BluRay player all output audio through the Pioneer but when watching just the TV (connected to an antenna) no sound is output, just a stuttery buzz.

    I'm guessing this is because over the air digital TV audio is some different type of format or something? If so, is there any kind of cheap gizmo to fix this? It's not super important because the main audio I need to sound better will be movies through the external devices. Not much on over the air TV except the news and the NFL.

    Thanks in advance.

    hawaii.ken

    Posts : 157
    Join date : 2012-01-31

    Re: Question about TV audio

    Post by hawaii.ken on Wed Jul 24, 2013 8:20 pm

    Dave_in_Va wrote:RCA out into the aux. in of the Pioneer.
    Do get any sound when you switch the Pioneer to Aux?

    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Re: Question about TV audio

    Post by Dave_in_Va on Wed Jul 24, 2013 8:38 pm

    Yes. Leaving the Pioneer in Aux. I get the stuttering buzz while watching TV but if I switch the TV inputs (not physically...just using the remote control) to the Roku or either of the DVD players, the sound is fine.
    Which leads me to think the audio format coming in through the antenna (over the air digital TV) is a different type of digital audio than is output through the HDMI of the Roku or the DVD players.

    TMadden

    Posts : 99
    Join date : 2011-12-22

    Re: Question about TV audio

    Post by TMadden on Wed Jul 24, 2013 8:41 pm

    Do you have an option in the TV's audio set-up menu to switch between PCM or Bitstream digital output? I think your V-DAC is expecting PCM?

    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Re: Question about TV audio

    Post by Dave_in_Va on Wed Jul 24, 2013 9:21 pm

    I will check that. Thank you.
    (It's been 2 years since I set up my TV.)

    skriefal

    Posts : 116
    Join date : 2011-09-20
    Location : Utah, USA

    Re: Question about TV audio

    Post by skriefal on Wed Jul 24, 2013 9:57 pm

    HDTV channels broadcast a Dolby Digital audio stream. This stream can contain 2.0 (stereo), or 5.1 (multichannel/surround). Your TV is probably like most newer models, and is sending that Dolby Digital stream directly out on the digital outs, expecting that you'll connect it to a home theater receiver.

    Most standalone DACs like your V-DAC II cannot decode Dolby Digital. If you're lucky your TV might have a menu option to force PCM output. This will force the TV to decode the Dolby Digital stream to PCM, which your V-DAC II can then decode to analog.

    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Re: Question about TV audio

    Post by Dave_in_Va on Wed Jul 24, 2013 10:00 pm

    After poking around in the menus and the TV's (crappy) instruction manual, I think the default is PCM but there are some advanced audio settings that are greyed out on the menus. I suppose they are active on a more expensive model.
    I'm going to call a local TV station tomorrow and see if I can talk with a tech.

    (Edit after reading the last post: Your reasoning sounds right. I just can't find anything in the menus that apply. The choice of "surround" is set to "off".)

    skriefal

    Posts : 116
    Join date : 2011-09-20
    Location : Utah, USA

    Re: Question about TV audio

    Post by skriefal on Wed Jul 24, 2013 10:42 pm

    I'm not surprised. Many newer televisions don't have an option to force stereo PCM output. They can usually pass through PCM from a connected Blu-ray /DVD player or cable box, but will send only Dolby Digital when tuned to an off-air channel. The same models often don't have analog outputs. With those your choices are limited to using the built-in speakers (ugh!), using a home theater receiver or pre-amp (with Dolby Digital support), using an external HDTV tuner box (but make sure that it doesn't have the same shortcomings as the TV's built-in tuner!), or buying a DAC that supports Dolby Digital (AC-3) decoding.

    Dave_in_Va

    Posts : 128
    Join date : 2013-04-02

    Re: Question about TV audio

    Post by Dave_in_Va on Wed Jul 24, 2013 11:15 pm

    skriefal,
    Thanks for the info. All of that makes sense. I'm just not going to sweat it. I can use the DAC for the the movies and TV shows on my streaming services and that's the main thing.
    ALSO...now I can run an RCA cable from the TAPE OUT of the Pioneer over to my soon to arrive SP 10 into my ST-70 out into my real speakers. That'll be be for the good stuff.
    I'll just have to use the TV's internal speakers for the local news and the Redskins games. That's cool.

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