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Digital Output Data Rate

Discussion in 'Desktop & Laptop Computers Forum' started by felix_li, Jun 28, 2005.

  1. felix_li

    felix_li
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    Hi,

    I've two questions about the digital sound handling in HTPC and apprecipate if someone can help:
    1. How to ensure the HTPC is outputing CD and WMA loseless in 16 bits/44.1 PCM & without any processing in-between?
    2. In Hi-Fi world, there're some up-sampling (e.g. 16 bits to 24 bits) techniques like AL24 in Denon and K2 in JVC. Is there any good software/hardware can do similar functions before sending the signals to sound card & S/PDIF?

    Regards, Felix
     
  2. owain_thomas

    owain_thomas
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    hi felix,

    to output bit perfect CD audio you need to bypass kmixer. this is windows software which resamples and messes about with perfectly good audio. there is a lot of debate about whether its effects are audible but personally I'm just happier knowing the music is not tampered with. In order to bypass kmixer you'll need a soundcard and media player which can use kernel streaming or ASIO. some examples of soundcards: Maudio Revo, RME HDSP9632, LynxTwoB. There are doubtless others. For music playback I use foobar2000, it offers great quality, lots of options and is very compact. winamp can also do ASIO/KS. To test if you are getting bit perfect you need to play back a DTS .wav file via digital output, if your AV processor is getting a bit perfect stream it will play fine, if its been tampered with it will be just white noise.


    Foobar does upsampling if you want it to. I've not really heard a difference with this turned on myself but YMMV.
     
  3. LTJ

    LTJ
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    Felix i hope I've got this right?
    Right I'm using a AMD 3000xp asus32bit MB and windows xp. At the moment I'm using an off board sound blaster Audigy2NX 24bit sound card(it is available as a sound card, ie fitted in the PC).

    Once the drivers are loaded it will upsample everything including mp3's to 24 bit 96khz if you desire. I'm using the 96khz option and coming out of the sound card optically and into a musical fidelity x-dac -old model-which will do 96khz. Then from there analogue audio stereo output into -in my case-digital home built two channel amps.
    I have to say it's the best sound I've ever had. Now a friend of mine has for some time been using a Behringer Ultra curve equaliser/dac

    http://www.turnkey.co.uk/tkweb/stockdetail.jsp?sku=BEHR-DEQ2496&context=WEB

    Now this device in conjuntion with their calibrated microphone allows you to measure two or one at a time speakers in room. Basically it's fed with pink noise at a high audible level and the microphone sends the results to the ultra curve that in turns compenensates in the digital area all peaks and troughs in the frequency response thus allowing speakers to be measured in the room they are actually used in and then corrected in their frequency response.

    This allows fantastic improvements. Now if you can't afford this device but have access to one , you can measure your speakers FR and take note and then transfer that to winamp. There is also a plugin for win amp that gives you a 32 band frequency response called Dsoft You can then set the frequency response for a flat performance onto this graphic equaliser with teh results taken from the ultra curve.

    I now get the best sound digitally that I've ever had.

    Several more tips.
    Use proper glass optical cable- not the cheap stuff.
    Silver cable outside of an optical option is the best you'll get.
    So far I haven't seen a silver usb to a cable (made my own) but you can get the low oxygen copper type and they do sound better.

    Back to the sound card, I'm sure that there are better sound cards out there, but the Sound blaster audigy2nx does 24 bit and will upsample to 96khz but the audio ouput on the sound card is no where near as good as going to a DAC even better, one that can do 96khz. Of course get the Behringer Ultra curve which not on will give your speakers perfect in the room flat response but also take the optical out put from the creative sound card and provide 96khz samplings rate.
     
  4. LTJ

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    Hello Owain. How do you turn off kmixer. When you use foobar is it affected by kmixer?
    Thanks
     
  5. owain_thomas

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    to turn kmixer off you need to use either the kernel streaming plugin or ASIO plugin for foobar. just download them, install them and select them in the Output section of preferences. not sure whether you can use them with audigy soundcards though. if you want to check that you're getting bit perfect output turn off any upsampling and send a DTS wave file via your digital output to a home cinema amp, if it plays then you're getting bit perfect, if not its being altered in some way.

    hth
    owain
     
  6. felix_li

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    Hi,

    Just back from somewhere w/o (or very expensive) internet. Sorry for my late thanks for your answers!!!

    Hi Owain,

    Because I'm currently storing some CDs in Lossless WMA and using WMP as my player, and I would like to convert ALL my CDs for permanent storage & convenient retrieval. So, what would you suggest? (WMP, somehow is quite easy but I don't want it to touch the digital data as well).

    Hi LTJ,

    I'm from Hi-Fi world and in Hi-Fi world, the CD 16 bits/44.1 KHz data are up-sampled to 24/96 or 24/192 DAC for processing. During this processing, every vendor has its own methods, like AL24 in Denon & Hi-bit insert by Pioneer.

    Basically this upsampling is by over-sample the data and use a technique (everyone has its own) to insert the "missing" data. As I think PC is a much powerful generic processing machine and is wondering if there's any specialist (software/hardware) in this area.

    As I've 3 DACs (the AMP, an CD/DA and a separate D/A), if there's no decent upsampling mechanism, I would prefer the PC just simply output the raw data out and let the DACs do the rest instead.
     
  7. owain_thomas

    owain_thomas
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    hi felix,

    if you want to store all your CDs then I would chose one of the following: either just save the wav files themselves, or if space is a premium and you need tags (artist, song name, album, etc) then use a lossless format like monkeys audio or flac. I've only ever used monkey's and always found it to be brilliant. can't speak highly enough of it. use exact audio copy and you can be sure you're getting the very best possible result.

    hth
    owain
     

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