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Question Regarding HTiB DVD System and Audio Connections Associated


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5 replies to this topic

#1 of 6 OFFLINE   ElementalVibe

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Posted December 02 2009 - 04:17 PM

I'd just like to start out by saying I'm relatively new to the whole Home Theater Setup and such. I recently acquired, over the past few months, a great interest in the workings of speakers, HT setups, and the like. I've researched some things in my free time but still have some lingering questions on setting up my own little thing in my room.

My dad left me a DVD "Home Theater in a Box" system that comes with its own basic speakers and subwoofer (it's 5.1 surround). Here's the model and its specs: www.retrevo.com/search. The Front L/R, Rear L/R, and Subwoofer speakers are all plugged into the back of the system. It's nothing special, really, but as a beginner that's experimenting and all, it does me just fine I think.

I am looking to purchase a monitor for Christmas and am pretty confident on buying this one (multiple inputs for video was my main interest): www.newegg.com/Product/Product.aspx. The reason I am looking into a monitor rather than a TV is, one, my room wouldn't be able to display anything bigger very well, and two, it's practically a portable HDTV I can use at college and such.

Ok... With all that being said:

I plan to use my laptop's HDMI out port to plug into one of the back HDMI input ports on the monitor as well as plugging my game console (be it PS3 or XBOX 360) into the other HDMI input port (there's 2 total on the monitor). The monitor has a headphone out jack on the right side, allowing output of sound (it also has an optical audio out on the back). I would also like to plug my iPod into the RGB Audio IN Port via a 3.5mm male to 3.5mm male cable.

My question lies here: If I were to use a 3.5mm male to 2 RCA male cable (www.monoprice.com/products/product.asp), would the monitor be able to take the digital input of audio from any given HDMI cord and output it through the analog left/right ends? The 3.5mm end would connect into the monitor, obviously, and the left/right analog ends into the audio output jacks on the back of my DVD/HTiB system. If so, will it output 2-channel or 5.1 audio to my speakers? Does it depend on whether or not the source supports 5.1 (e.g. playing an older game that doesn't support 5.1 versus one that does)?

In regards to the above questions, I devised another possible plan if the above option wasn't plausible. How would a Digital to Analog Converter Box work? Something like this: www.gefen.com/kvm/dproduct.jsp. I figured I could use an Optical TOSLINK cable from my monitor and run it to this converter. Then from there I would have left/right audio cables (male on both sides) plugged into the converter on one end, the other end plugging into the DVD/HTiB audio out jacks. Should I void this method completely? This method, as I see it, produces the same result as my first configuration with the 3.5mm/RCA cable, just way more expensive. Would there be any advantage to this method?

I guess my main concern is what option will actually give me sound to my speakers with my game consoles, laptop, and iPod? Which option will then give me a 5.1 surround sound? Will both work the same way? Any recommendations on a more efficient way of setting this up?

Meh... I know this is a lot of random questions/information. xD Nonetheless, any advise is greatly appreciated, and I value any poster's time on helping me with this whole thing. Thanks in advance.

Regards,
Stephen


#2 of 6 OFFLINE   Jason Charlton

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Posted December 03 2009 - 03:04 AM

Hey Stephen - welcome to the forum!

You sort of hit the nail on the head when you mentioned "It's nothing special, really, but as a beginner that's experimenting and all, it does me just fine I think."

What you're experiencing is exactly what happens when someone decides to expand on an HTiB system.

First of all, let me clarify a few points that may help you figure all this out.

5.1 (or higher) Surround Sound
5.1 surround sound (or 6.1/7.1) can be carried in two different ways.  1) Digitally - via a single coaxial/RCA cable, a single optical/Toslink cable, or piggyback with video on an HDMI cable.  2) Analog - with EACH audio channel (6 in total) on it's OWN coaxial/RCA cable.

When carried digitally, the device that receives the signal must be able to decode the digital signal, convert it to separate analog signals, then route it to the speakers.  That's part of what the A/V receiver is designed to do for you.

2-Channel RCA cables cannot carry anything other than stereo analog audio.  All 5.1 information is lost in the downconversion to this format, so once it's down to 2-channel, there's no going back.  The digital to analog box you listed would do this, but you'd lose surround sound audio for each source plugged into it.

Digital Audio out on TVs
In virtually every case (the exceptions are very few and far between) a digital audio out on the back of a TV will ONLY carry a digital 5.1 signal for broadcasts originating in the TVs own tuner.  Any external audio streams that come into the TV and are re-routed out get downconverted to 2.0 stereo first.

Which brings us to the base root of the problem - too many sources and not enough inputs.  From what I can gather on the HTiB system you have - is that it has only 1 digital audio input (plus 2 analog stereo inputs).  That means that only 1 source other than the built-in DVD can utilize digital surround audio.

I don't think there are any video inputs on the HTiB, so you are correct in planning to route all video signals directly to the TV.  Even though the video signal goes to the TV, you can still send the audio signal from each source to the HTiB.  Whichever one you want to preserve the 5.1 should go into the digital audio in on the HTiB.  The other sources will have to make do with the analog stereo connections on the back.

Expanding your Sytem
Many people are satisfied with the simplicity offered by HTiB systems and never look back.  Clearly, you have bigger aspirations and have already "outgrown" the all-in-one.  As you look to expand your system, you'll have to decide which components get precendence.  Do the speakers in this system have proprietary connectors?  If so, then you'll be forced to upgrade your receiver and speakers at the same time.  If not, then you can decide which to focus on first - speakers or receiver.  A good receiver will have enough inputs to handle both video and audio from all your devices.  Then you merely run a single video out from the receiver to the display monitor and you're all set.

Hope this helps.  Please let me know if any of my assumptions on your HTiB were incorrect - it still may be tricky to hook up more than a couple of sources to your system, no matter what.

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#3 of 6 OFFLINE   ElementalVibe

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Posted December 03 2009 - 10:25 AM

Hi Jason,

Thank you for the quick response. Your information was very helpful.

I forgot to mention one key point, however: The DVD system I have only has two pairs of audio inputs. They are both analog audio inputs (white/red RCA) and are labeled "TV IN" and "AUX IN." The only digital jack on the system is one coaxial digital out (I was surprised when I noticed there were no digital inputs at all). From reading what you posted, I am inferring that only a DVD disc placed in the system would be able to utilize 5.1 surround sound. However, I recently tried plugging in my Xbox 360 into the "TV IN" audio inputs with a game that supported "Dolby Digital." I noticed that the sound was still split amongst the speakers as it should be in a genuine surround experience. The screen display on the DVD system even displays "DDolby II." I'm glad that it works, but this has me somewhat confused as to why it does, so any insight on this would be appreciated.

Also, you said, "2-Channel RCA cables cannot carry anything other than stereo analog audio.  All 5.1 information is lost in the downconversion to this format, so once it's down to 2-channel, there's no going back.  The digital to analog box you listed would do this, but you'd lose surround sound audio for each source plugged into it."

Does this mean that my initial idea of using a 3.5mm male to 2 RCA male cable will still work? Again, the 3.5mm male end would plug into the headphone out jack on the TV and the 2 RCA ends would plug into the audio input jacks on the back of the DVD system. I am a bit confused on whether I can use this cable or if I should use the converter box (optical out on TV to box, RCA white/red cable from box to DVD system). I would be leaning more towards using the 3.5mm/RCA cable simply because it's cheaper. However, if it won't work, then the converter box is seemingly my solution. If they both work, which way would you recommend for a better overall experience, price set aside?

Thanks for taking time to help me, and hopefully I can grasp how all this would work out.

Regards,
Stephen


#4 of 6 OFFLINE   Jason Charlton

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Posted December 03 2009 - 02:06 PM

Hi Stephen.

Thanks for the clarification on the audio inputs.  A site I found online had indicated one digital input, but clearly that's not the case.  So yes, you'll only get true Dolby Digital 5.1 from DVDs played on the system.

The "DDolbyII" indication refers to Dolby ProLogic II - that's a simulated surround sound audio format (a newer version of Dolby ProLogic which has been around for a while).  DPLII takes a stereo source and derives a simulated 5.1 mix from it.  It's a pretty effective method, but still not the same as true digital surround sound.

Honestly, I can't be certain if using the headphone jack would be the same as routing the audio from the other sources to the analog stereo inputs on the receiver.  Yes, the headphone jack would carry a stereo signal, and I imagine it would output the audio of whichever source was selected, but I'm not certain if the audio level would be the same (I've never tried doing this before).  As you said, the 3.5 mm to RCA cable is cheap - I would suggest giving it a try and seeing if it works.  If so, then you're not missing out on anything, as you're stuck with stereo for external sources until you decide it's time for a new receiver.

Good luck!

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#5 of 6 OFFLINE   ElementalVibe

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Posted December 03 2009 - 04:49 PM

Jason,

Ah, I see. Since the DVD system cannot output digital audio and only analog, a DVD played on the system is the only way to get the "true" 5.1 surround sound. I did a test earlier today with a few different games and such on the DVD system. The simulated surround sound is more than enough to satisfy my current expectations.

I did some further research on the Gefen Converter Box model that I linked earlier. It seems to be more of an HTPC luxury and/or item for older receivers that do not incorporate digital inputs. This avoids spending a large sum of money on a new receiver altogether. The box takes the true digital 5.1 Dolby surround sound (it doesn't support 6.1 or 7.1) and outputs it as analog audio. The analog audio output would then either be a simulated 5.1 mix or 2-channel stereo audio output (whatever the source supports I'm assuming). With this deduction, I think that the 3.5mm/RCA cable should be sufficient for me. I don't see why it wouldn't work, but it all comes down to when I actually get all the gear and test everything.

As for when you said, "...I'm not certain if the audio level would be the same (I've never tried doing this before)," I'm assuming you mean the TV's volume in association with the source's because of the 3.5mm/RCA cable used? If not correct me, but I can post again sometime in January after I have a bit of fun messing around with all of this. I'll let you know how it all goes down.

Again, I appreciate your instrumental help. I'm glad there are people like you that are willing to share tech knowledge with others and, in general, guiding them to informed decisions.

Regards,
Stephen



#6 of 6 OFFLINE   Jason Charlton

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Posted December 04 2009 - 12:45 AM

My pleasure.  Good luck!

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