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I Need Advice On A Specific Cable


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6 replies to this topic

#1 of 7 OFFLINE   kooney

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Posted January 04 2010 - 12:49 PM

I have an LG HT409SA Home Theater in a Box and i was wondering whether i could split the signal to imitate surround sound while watching tv. The problem i ran into was the fact that i have rogers basic cable box and an older tv with just 3 A/V slots. The rogers box happened to have a digital audio out though on the back of it. As well the receiver for the LG system had an optical port on the back of it. So i decided that i needed both a coaxial cable as well as an opitcal cable, however i need to find out which kind of converter to buy. Do i need a coax to optical that has coax in and optical out or do i need a converter that has coax out and optical in ? any help would be great.

#2 of 7 OFFLINE   Joseph DeMartino

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Posted January 04 2010 - 01:54 PM

I'm having a little trouble following your post, and I'm not entirely sure what you're trying to accomplish.  It doesn't help that I can't find anything to match the LG model number you provide - other than this thread, that is.  /img/vbsmilies/htf/smiley_wink.gif  Any chance there's a typo or transcription error in there? 

I don't think you're trying to "split" the signal nor do I think you want to "imitate" surround sound.  Isn't your HTiB a surround sound system already?  I think you're trying to get digital audio from your digital cable box to your HTiB.  If you have HD cable you should be getting honest-to-goodness Dolby Digital 5.1 from most of your HD broadcast and cable programming, and Dolby Pro Logic matrixed surround from nearly all of the reast.  

It sounds like your cable box has a coax digital audio output, and your HTiB has only an optical digital audio in.  If that's the case you need an adapter that can convert coax to optical.  You simply need to follow the signal path from the source component to the destination. 

It would help if you could list the make and model of the cable box (by manufacturer, not cable company: "Rogers"  doesn't really tell us anything, since cable companies don't make their own equipment and a Rogers customer in one city might have a Motorola box while a Rogers customer in another might have a box from Scientific Atlanta.)  Also of the TV.  And please double-check the model on that HTiB because I'm coming up with zip on the LG site, even checking discontinued items.

Regards,

Joe



#3 of 7 OFFLINE   kooney

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Posted January 04 2010 - 02:08 PM

it's a rogers scientific atlanta 3100 series standard cable box, and sorry about the LG model number its actually the HT904SA http://www.lge.com/c...tem-HT904SA.jsp I just cant connect any other way than through a converter, im thinking about getting one of these guys http://www.tigerdire...60712&CatId=466 im just not sure whether i need to get that one which has the coax in and the optical out, or if i need the one with coax out and optical in. I'm assuming thats the one though because i would be going from the digital audio out of the cable box into the converter and using an optical cable out of the converter box and into the receiver?

#4 of 7 OFFLINE   theadvisor

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Posted January 04 2010 - 02:49 PM

He is trying to get digital sound with an SD video feed.

SD video is paired with stereo sound (2.0).  You could technically upgrade to an HD cable box to get the digital sound (5.1) out to your HTiB setup, but I do not believe that will work either as the box will want to give you an HD video feed (which your television does not support) with the digital sound.  Even if you connect everything properly with an HD box, when you are watching SD channels you will get stereo audio.  I do not believe it is possible, even with the appropriate hardware on your end, to split the feeds.  This is true for the converter you have listed as well.

The only possible way to make this work is to have two cable boxes, on SD and one HD.  The HD one would broadcast the digital sound to the HTiB, and the SD unit would broadcast the video feed to your TV.  Even if you went to this length, it would not work 100% as SD and HD feeds are often not identical.  Since they are two separate feeds from the broadcasters perspective, they can have different ads, and the timing can be off slightly (I work for a cable operator).  I would not suggest this whatsoever, as it is pointless and silly.  Just talking through the exercise for example.

You could put both left speakers (front and rear) into the front left HDiB output, and do the same for the right.  This will make sound come out of all four speakers, effectively doubling the standard stereo output. You would have to put it back every time you wanted to watch a movie though as the rears would be technically disconnect from the HTiB. 

You should run the optical cable from the cable box to the HTiB as some movie channels will broadcast movies with surround sound.  Your problem is more related to the cable feed you are receiving then the wiring on your end. If the video only has stereo sound then thats all your speakers will play.  If 5.1 is available it should automatically play in surround if you have it wired up correctly.

Hope this helps. -Matt


#5 of 7 OFFLINE   Joseph DeMartino

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Posted January 05 2010 - 02:50 AM

An HD cable box will transmit the standard-def channels just fine, and downcovert & letterbox the HD channels if connected via the composite video cable.  So there's no need for a "two box solution".  /img/vbsmilies/htf/biggrin.gif">

Adam, you can get basic "surround sound" (matrixed Pro Logic rather than disecrete 5.1) using the digital output on your current cable box.   You may also get full 5.1 from HD channels.  Check with Rogers. 

Again, understanding the connection is simply a matter of following the path the signal is taking. You are going out via coax from the cable box and in via optical to the HTiB.  Therefore you need an adapter with a coax input and an optical ouput.  The Amazon link in my earlier e-mail goes to the same

#6 of 7 OFFLINE   kooney

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Posted January 05 2010 - 04:24 AM

thanks guys, i will give it a shot with the converter you suggested through amazon and get back to you with the results.

#7 of 7 OFFLINE   theadvisor

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Posted January 05 2010 - 06:32 AM

Sorry for getting a little off topic there.  I read that you were trying to get 'surround sound' out of your HTiB while watching broadcast SD channels.  If setup via coax, the cable box should only broadcast sound through all the speakers when it is available, otherwise you will get stereo sound through your HTiB.