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Discussion Starter #1
Creative Sound Blaster X-Fi Xtreme Audio 7.1 Channels 24-bit 96KHz PCI Interface Sound Card is what I'm thinking of using. Since Mythtv is just passing through the digital stream, does the sampling rate of a sound card change anything. Also the same question for the SNR, does a better SNR on a sound card mean that I will have less noise in the signal in Mythtv.


I ask these questions since I'm only going to be using SPDIF out to my AV Receiver.
 

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Chaintech- AV710, can't say enough about this card http://www.newegg.com/Product/Produc...82E16829120103


As far as the article goes as an EE who specialized in both digital and analog signals there are quite a few comments made in the article that made me take much of what was written with a grain of salt. For example 12 guage wire???? Sure if you've got an audio amp that powers 1000 watt speakers!!!
 

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I believe that is true with all sound cards since the ALSA drivers default them to analog ports, plus I hate the configuration file for ALSA...I still find .asoundrc file configuration to be not the easiest to understand.


But once I got that file configured correctly along with mplayer configured correctly I can now pass thru PCM, AC3, DD, & DTS flawlessly and bit perfect
!
 

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Discussion Starter #6

Quote:
Originally Posted by bac522 /forum/post/0


I believe that is true with all sound cards since the ALSA drivers default them to analog ports, plus I hate the configuration file for ALSA...I still find .asoundrc file configuration to be not the easiest to understand.


But once I got that file configured correctly along with mplayer configured correctly I can now pass thru PCM, AC3, DD, & DTS flawlessly and bit perfect
!

Could you post you ALSA config files so that I have a reference, I just bought the card you suggested.
 

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I also configure mplayer with the following options -ao alsa -ac hwdts,hwac3.


My .asoundrc file is:


pcm.!default spdif


pcm.spacespdifdmix {

type dmix

ipc_key 83484784

slave {

pcm "hw:1,1"

format S32_LE

buffer_size 1024

buffer_time 84000

rate 44100

}

}


pcm.asymed {

type asym

playback.pcm "spacespdifdmix"

capture.pcm "hw:1,1"

}


pcm.spacespdif {

type plug

slave {

pcm spacespdifdmix

}

}


pcm.!default {

type plug

slave {

pcm spacespdifdmix

}

}


# For ogle


pcm.!spdif {

type plug

slave {

pcm "hw:1,1"

format S32_LE

}

}


# For mplayer, ao (mplayer -ac hwac3, -ao alsa9:mplayer)

# For vlc, use mplayer as alsa device


pcm.!iec958 {

type plug

slave {

pcm "hw:1,1"

format S32_LE

}

}


pcm.mplayer {

type plug

slave {

pcm "hw:1,1"

format S32_LE

}

}


pcm.snes9x {

type plug

slave {

pcm "hw:0,0"

format S32_LE

rate 48000

}

}
 

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Just a note to the above .asoundrc file. My sound card is at hw:1,1, but sometimes the chaintech sound modules are installed before the motherboard sound card modules which means you may need to change hw:1,1 to hw:0,1. One good way to tell is just type aplay -l at a shell prompt.
 

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I've had good luck with the M-Audio Revolution 7.1, though I've only tested analog outputs on that. I also use it for measurements when doing speaker design... Ubuntu has had no problem with the onboard sound (one Realtek, one nVidia nForce 5 series) or older SB cards. I've never had to do anything to get them to work via analog, though I've run into the "only one channel plays" bug and had a helluva time so far via spdif (could only get stereo, and now I can't get anything at all). The real trouble is always always with config.


Quote:
Originally Posted by bac522 /forum/post/0


For example 12 guage wire???? Sure if you've got an audio amp that powers 1000 watt speakers!!!

This is off topic, I'm not sure you've been given the whole picture. I run 18 inches of 12ga wire from amp to speaker in my main stereo system (though that's a little overkill, it's only a little overkill... I had it on hand since I use it in other systems) The longer the wire run, the higher the wire impedance. And the higher the impedance, the more it alters the tuning of your speaker (generically, it increases system Q [generally bad] and it also tends to lower output 500Hz down...) So you lose output and gain slop in bass response. In a sealed system with 2 8" drivers and a 4ohm nominal load, increasing series impedance by 1/2 ohm can dictate a 25% increase in box volume to maintain the same tuning. If it's a bandpass sytem, the port also has to change length...


Also, speakers aren't rated by wattage, and amps are only sort-of rated by wattage. :p Speakers might be rated by peak power handling (measured in watts) but that doesn't tell you whether that's the point at which things will melt down, or the point at which you're operating your drivers beyond their xmax limits. It's usually the former, however, meaning it's a relative moot point for any driver that delivers bass outside of specific scenarios (subs in cars can have such small boxes they CAN reach those thermal limits - same with pro gear) And amplifiers are rated by wattage at a certain impedance load, so it's only rarely a static number since only ribbons and planars tend to be resistive loads.


C
 

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Discussion Starter #10

Quote:
Originally Posted by bac522 /forum/post/0


Just a note to the above .asoundrc file. My sound card is at hw:1,1, but sometimes the chaintech sound modules are installed before the motherboard sound card modules which means you may need to change hw:1,1 to hw:0,1. One good way to tell is just type aplay -l at a shell prompt.

Thank you for the help. The chaintech arrived today and I will play with it soon. The reason I'm even using the chaintech is that my onboard sound card on my asus MB might be causing a problem for my setup. I get some noise on Left Front and Right Front speakers when I'm playing from a dvd. It doesn't happen when I play music. I also must say that I have all the audio being routed to the spdif, so everything is digital going to my AV receiver. It sounds like its fan noise coming from the speakers so I don't know where its coming from since everything is digital. Its also very low volume noise, i don't here it unless the movie is in a silent section. Its not my receiver, its a Denon AVR-4306 and sounds very good when playing the FM radio, no noise.


Just wondering what could be wrong.
 

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Quote:
Originally Posted by rfisher1968 /forum/post/0


It doesn't happen when I play music. I also must say that I have all the audio being routed to the spdif, so everything is digital going to my AV receiver. It sounds like its fan noise coming from the speakers so I don't know where its coming from since everything is digital. Its also very low volume noise, i don't here it unless the movie is in a silent section. Its not my receiver, its a Denon AVR-4306 and sounds very good when playing the FM radio, no noise.


Just wondering what could be wrong.

Strange, digital is digital, unless the onboard sound chip is re sampling the sound and introducing the noise. Since you have the AV-710, I'm not so sure I'd worry about troubleshooting it. I know that I play music and movies through it without any extra noise and I know for a fact that it's bit perfect pass-through. What app are you using to play the DVD?
 

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I cannot get my M-audio Revolution to work, I am very new to linux (using linux mint). Any help if someone can spare the time, would be greatly appreciated. I manage to get the test tone working in the sound area but get no sound from the desktop or mplayer. I am using spdif output. I do not know my way in linux terminal, which makes editing config files difficult at best. Help?
 

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For starters, try analog outputs. I had the same problem in my HTPC before upgrading to the REVO (which I've not yet used in Linux, so who knows what configuration hell I still have before me). I had to do some configuration to mplayer to get it to send signal to S/PDIF but even then the best I could get was stereo.


Second, learn your way around the shell (terminal). And vi (though I prefer vim). There will be times (most often with graphics drivers) where X suddenly fails. And all you have is shell access.
It's actually quite simple, just not what you're used to.


C
 
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