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Problem with analogue sound when using DVI to HDMI cable

Discussion in 'Computer Components' started by rnjmorris, Sep 3, 2005.

  1. rnjmorris

    rnjmorris
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    Hi again everyone,

    I recently posted here:

    http://www.avforums.com/forums/showthread.php?t=238029

    and thanks to the very helpful responses have now invested in a DVI to HDMI cable, running from my ASUS Nvidia N6600GT video card to the HDMI port on our JVC LT-26S60B LCD TV. However, I've run into a small problem and no amount of searching has led me any closer to a solution (or, indeed, anyone else who has experienced the same thing).

    In a nutshell, when I've connected the PC to the TV via the DVI to HDMI cable I need to set the TV's HDMI audio setting to "Analogue" (or "Auto", it has three settings..."Digital", "Analogue" and "Auto") in order to get sound through another cable which I connect separately. This works fine and I'm able to both view and hear video files played from the computer, BUT, as soon as I change the aforementioned setting to Analogue, I get a repeated, very short (fraction of a second) burst of static from the speakers every one and a half seconds. It's not loud enough to interfere with most of the video files I watch although it is audible during quiet sections. To give a better idea of what it actually sounds like, with the TV's volume setting on about half way it sounds very like an old fashioned mantelpiece clock in the same room. Changing the setting to "Digital" stops this immediately but I am, of course, then left without any sound as none is carried on the DVI to HDMI cable.

    After a lot of experimentation I've noticed the following:

    1. The sound is not related to anything carried on the analogue audio cables (red and white connectors connected to ext-4 on the TV). It is present even when they are disconnected.

    2. The sound does appear, in some way, to be related to the resolution I set the graphics card to. At higher resolutions the sound is slightly higher in pitch. If I reboot the computer and view/listen to the output on the TV the sound stops momentarily (or becomes a continuous hiss) as the screen changes from the initial loading screen (with BIOS info) to the Windows 2000 loading screen to the Windows login screen. However, I've used a number of different resolutions with what I believe are the appropriate refresh rates but nothing stop the sound.

    3. When connecting via S-Video this problem is not present.

    Does this sound familiar to anyone, or does anyone have a theory as to what might be causing it? If possible I'd like to try and establish if any of the components involved (i.e. video card, cable, TV) are faulty in any respect as they're all under guarantee.

    Many thanks in advance for any thoughts!

    Kind regards,

    Rod
     
  2. richjthorpe

    richjthorpe
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    Hi Rod,

    How are you connecting the audio cable and what sort of audio cable is it ? If you are using the SPDIF output from the motherboard, you only need a single RCA cable (For digital mind) to the Digital input on the TV, if it has one.

    If you are connecting a cable with a 3.5mm jack at one end and 2 RCA cables at the other (I think you are by the sounds of it) make sure you are plugging in the cable to the stereo output on the soundcard and not the SPDIF. At the TV end, make sure the EXT 4 is for the PC input on the TV.

    Richie.
     
  3. rnjmorris

    rnjmorris
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    Hi Richie,

    Thanks for that. Unfortunately(!) I'm pretty sure the cables (indeed the 3.5mm jack/2 RCA combo mentioned) and the settings on the TV are connected properly. Everything works as expected, sound and video, with the exception of this repetitive noise. Crucially, even with the audio cable disconnected completely, the noise is present as soon as the picture is sent down the DVI2HDMI cable.

    As I haven't heard of anyone else with the same problem I suspect either there's a fault somewhere or it's a bizarre electrical quirk which will be impossible to identify/fix...

    Thanks for the post though, much appreciated.

    Cheers,

    Rod
     
  4. richjthorpe

    richjthorpe
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    Next thing t d is to disconnect the DVI2HDMI cable with just the sound cable cnnected and see if the sound is there without distortion.

    If it is, then it points to the video cable. It might be that it's not properly shielded and getting interference from somewhere.

    Richie.
     
  5. rnjmorris

    rnjmorris
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    Thanks Richie, I'll give that a go.

    Cheers,

    Rod
     

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