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Need advice on audio for future HTPC build

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September 1, 2009 11:05:46 PM

Howdy all! Brand spankin' new to the forum.
I am in the planning stages of building an HTPC and am unable to get some clear information on audio in general and there are two paths.

1. Onboard audio on mobo or
2. Soundcard.
I am leaning towards a mATX board in a large case for more room.

When I do get the HTPC (with Blu Ray) built it will all pass through my Denon receiver that decodes HD-Master and HD-DTS so I won't need the PC to do it..... and that is where my question comes in.

Are there mobo's with audio, or cards, that will pass through the HD audio via HDMI? Right now I have my home theater system set up for my Panasonic Blu Ray player to output a bitsream via HDMI to the Denon which rewards me with a happy blue light.

I already gather the audio output of the BD is software driven.
Anybody got a direction I should head or something to research?
Thanks for any help. I know I'm gonna need it (1st time build coming up!!!)

a b B Homebuilt system
September 1, 2009 11:49:53 PM

Welcome to the forum.

There are two ways to go about getting HD-Master and HD-DTS to your receiver.

#1 Either get a motherboard with an onboard GPU or discreet graphics card that can pass LPCM to your receiver. The PC does the decoding and passes the signal to your receiver. Onboard chipsets that support LPCM are the GeForce 8200/8300 for AMD or GeForce 9300/9400 and Intel G45 for Intel. For discreet cards, you'll want to look at the AMD/ATI Radeon 4xxx line of cards. You will also need to use a software BD player that supports LPCM output. I use Total Media Theatre and I believe it supports it.

#2 If you really want that "HD-DTS" to light up on your receiver by bitstreaming, you will have to pony up for one of the Asus Xonar sound cards that will pass the high definition audio over HDMI to the receiver to be decoded. The cheapest card that will do this is the Asus Xonar Slim, but it's still like $150.
September 3, 2009 12:48:12 AM

rwpritchett said:
Welcome to the forum.

There are two ways to go about getting HD-Master and HD-DTS to your receiver.

#1 Either get a motherboard with an onboard GPU or discreet graphics card that can pass LPCM to your receiver. The PC does the decoding and passes the signal to your receiver. Onboard chipsets that support LPCM are the GeForce 8200/8300 for AMD or GeForce 9300/9400 and Intel G45 for Intel. For discreet cards, you'll want to look at the AMD/ATI Radeon 4xxx line of cards. You will also need to use a software BD player that supports LPCM output. I use Total Media Theatre and I believe it supports it.

#2 If you really want that "HD-DTS" to light up on your receiver by bitstreaming, you will have to pony up for one of the Asus Xonar sound cards that will pass the high definition audio over HDMI to the receiver to be decoded. The cheapest card that will do this is the Asus Xonar Slim, but it's still like $150.



Hi RW. Thanks for the welcome and being the poor sap that I cling onto for the moment! But seriously, thanks for the help.

I looked at the Xonar Slim, researched LPCM vs. bitstream and up to this point the GeForce 8300 chipset. I had to stop as I just gotta ask another couple of questions.

First let me point out that I have a Denon AVR-2809 Ci. Not the biggest baddest Denon but it does decode HD master from bitstream on my Panasonic BD35. Terminator 2 just about broke my house the other night!! So, far as I reckon, I don't really need LPCM. Or am I wrong? Might have to do some testing if the wife will put up with it. The thing is that I really don't need, or want, the PC to do be doing the decoding because of the receiver being more than capable with bitstream (unless it is proven that LPCM is better). Just one less task for the HTPC to heat up or bog down over.

As I am beginning to understand that if there is an HDMI output on the motherboard that does not necessarily mean that both audio and video are transmitted even if it is HDMI 1.3. It seems mostly just video. My damn Dell Studio/XPS laptop has an HDMI out but I can't get audio out of it to save my life.

So here is where I am getting lost.

1. If I go the onboard audio/video mobo with what you suggested in #1 does the HDMI socket output both video and audio? One assumption being that bitstream passes through.

2. Regarding discrete cards such as your suggested AMD/ATI Radeon 4xxx series and onboard audio of mobo. How do you get sound out of a GPU? I get the feeling that possibly the onboard audio of a mobo gets hooked up to the GPU and video/audio then both get output the HDMI of the GPU?

3a. GPU card and Xonar. If Xonar passes bitstream through does the Xonar card somehow hookup to the GPU and audio/video out HDMI of GPU (or vice versa)? Or would I have to use two seperate HDMI cables for audio and video? That seems dumb to me. May be a stupid question there.

3b. Onboard video (AMD 785 chipset?) and Xonar. How does this work?

As you may be able to tell my main confusion is how to get the audio out when using any of the scenarios with just one HDMI cable since mobo and GPU and sound cards have HDMI outputs.

oh and #4.... have you been able to check your Total Media Theater to see if it does support the LPCM?
Thanks for your help.
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a b B Homebuilt system
September 3, 2009 3:12:43 AM

1. The HDMI that you get onboard with any of the chipsets I listed will pass both audio and video through the HDMI. None will pass High Def audio through bitstream.

2. The discreet Radeon 4xxx cards actually have a 7.1 audio chip on the video card. You disable the motherboard audio and use the graphic card's audio which gets passed through the HDMI along with the video.

GeForce cards do not have audio onboard, but the later cards (8xxx series and up I think) have a S/PDIF plugin that will allow you to pass the motherboard audio to the card to be output along with the video through HDMI. The Radeon approach is more simple IMO.

3a. The Xonar card works like this: The HDMI or DVI out from the motherboard/discreet video is connected to the "IN" HDMI port of the Xonar card. The Xonar card combines the video and the high def audio and sends it to an "OUT" HDMI port that goes to your receiver.

3b. Same as 3a.

4. I'm using TMT2 which is bundled with the Xonar cards so I'm pretty sure it works. TMT3 is out now and may work as well. There's also a new Auzentech sound card that will compete with the Xonar... but it's $250 and so far it only works with PowerDVD 9.

If you want to run a single HDMI cable, then either the 8200/8300 or 9300/9400 motherboards will do that with LPCM. If you need more graphics horsepower and don't mind the extra heat then a discreet Radeon 4650/4670 card will do the same LPCM. The Xonar setup is kind of two cables because you need that short HDMI cable bridge between the graphics and the sound card.

I'm only using S/PDIF for my HTPC w/BD setup right now because that's the best my receiver can handle. I've been salivating over going either LPCM or Xonar+bitstreaming for a while so none of this is first hand knowledge. I've just been researching the options myself but I don't think I can convince my wife that the high def sound is any better than standard Dolby 5.1. You can blame the movie studios for making high def bitstreaming so difficult on a PC.
September 5, 2009 7:33:54 PM

Sounds like I am going to go with the Xonar Slim.
I looked at the manual for it and it recommends NVidia GeForce 8400 and above or AMD (ATI) H2400 and above.
So I have to figure out whether I wanna go AMD or Intel for the Mobo huh?
As I am trying to avoid extra heat I think the onboard video is the way to go.

In fact here are some of my considerations:
I want as much room as possible to fit as many internal HD's as I can and have a large airflow

Standard ATX HTPC case. Here's a couple I am thinking of:
Thermaltake DH 202 http://www.amazon.com/Thermaltake-VJ80011N2Z-Digital-Bu...
Silverstone GD01B http://www.newegg.com/Product/Product.aspx?Item=N82E168...

A mATX mobo. Since I really only need at least one PCI connection for the XONAR and will have onboard video I don't have to worry about the whole size of a discrete video card blocking HDD's and the additional heat it would create.
Maybe something like this?:
GIGABYTE GA-MA785GMT-UD2H AM3 AMD 785G HDMI Micro ATX AMD Motherboard
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Although I might be a little worried about the PCI express 2.0 being that close to the NB or SB ( whichever it is) if I ever do decide to go discrete down the road.

Thanks for your help and for what it is worth I can tell a difference between hidef audio vs DTS. I just played around with Terminator 2 on bluray and on "extreme DVD", yes we have both, my wife is a terminator nut. They both have the same "you're watching THX" audio thing at the start and the HD master was better than DTS. But....the DTS was not bad at all. First part of the movie with the fighting in the future was better also. But that is my take with my system. Your mileage may vary.
Cheers.
!