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Thread: audio over USB v. optical

  1. #191
    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    Quote Originally Posted by durwood View Post


    If two 4 channels can be strung together on the EVAL board like Felix said, then we should be able to string 4-5, 2 channel higher quality DACS.
    see that's what I think.. these 8 channel dac's are consumer product grade... there probably not going to be much better than an average soundcard I think, in the end your just going to be building a soundcard.... I guess that could be a good thing though, cause you can still control the rest of the op amps & caps & board design, but in the end I don't think these are audiophile grade, there made to go in dvd players & portable little things... consumer grade...

  2. #192
    Constant Bitrate Felix509's Avatar
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    Supposedly the 24 bit Burr Brown PCM1794 chips are the hottest DAC chips right now. This is just going by how many High end DACs use it, and also the HIFI forums of the web generally like this chip. I suppose it is a bit subjective though, I have heard none of them personally, so just going by gossip..

    Here is a really neat article with Many of the Audiophile DAC chips..

    http://www.audiodesignguide.com/DAC_final/DacFinal.html

    Laters!

  3. #193
    Super Moderator. If my typing sucks it's probably because I'm driving.... turbocad6's Avatar
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    maybe the burr browns might be promissing, but how would they compare to the normal burr browns?

    I guess I was really talking more about the wolfsons & the other 8ch really....

  4. #194
    Constant Bitrate Road_Dog's Avatar
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    Quote Originally Posted by Road_Dog View Post
    No problem

    I may not write clearly, so it could have been my fault. Red made that apparent to me.

    I really would like to find a USB audio to 7.1 <something> chip for the front end instead of trying to write a media player that has to split the channels out to send it down the USB bus to 4 or so seperate converters to put it back together for the listener. I would think this is a nightmare and a band-aid.

    I have seen tons of USB to 4 1/8 inch jacks (or properitary like Turtle Beach's Roadie) for 7.1. I wondering if I should get my hands on one of them and tear it apart? Maybe it is not a bad idea. Be back!


    Road_Dog


    Okay, took my Roadie apart. Found they use a CM106-L chip which is a C-Media chip: http://www.cmedia.com.tw/?q=en/USB/CM106_plus

    Then I spotted this: http://www.audiotrak.net/maya44usb.htm and clicked on this picture: http://www.audiotrak.net/images/maya44usb_im3.jpg which they tell us the chip they use -- TI TUSB3200 (USB Streaming Controller) http://focus.ti.com/docs/prod/folder.../tusb3200.html. The data manual is located here: http://focus.ti.com/lit/ds/symlink/tusb3200.pdf. Linux drivers on SourceForge: http://sourceforge.net/mailarchive/m...sg_id=12923298. This chip does I2C, I2S, 8052 MCU (popular), and has crappy DACs like the PCM2770 also. The incoming (from USB) audio can be intercepted before it hits the internal DACs/CODECs. Dang it, not 7.1.

    Audiotrak has a 5.1 unit: http://www.audiotrak.net/mayaex5.htm. Trying to find out what chips they use. Both units have low 48 KHz sampling rate compared to previous finds of 192 KHz.

    The search continues


    Road_Dog

  5. #195
    Car Audio Moderator durwood's Avatar
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    Okay, took my Roadie apart. Found they use a CM106-L chip which is a C-Media chip: http://www.cmedia.com.tw/?q=en/USB/CM106_plus
    After I saw the spec on the chip, Imediately thought it was the one used in the roadie. I did alot of research on external cards when i did my sticky. So that chip is out. Not high enough quality.

    Supposedly the 24 bit Burr Brown PCM1794 chips are the hottest DAC chips right now. This is just going by how many High end DACs use it, and also the HIFI forums of the web generally like this chip. I suppose it is a bit subjective though, I have heard none of them personally, so just going by gossip..
    Felix, now that's nice. I don't think that is gossip. Those specs just look amazing. And it will do 4.5Vrms in stereo (9V rms mono). Wow, if we use that chip, combined witha little gain from the swappable opamps, we could easily get the output voltage we require. Plus I really like the Dynamic range of 129dB! Ya!

    24-Bit Resolution
    Analog Performance:
    Dynamic Range:
    132 dB (9 V RMS, Mono)
    129 dB (4.5 V RMS, Stereo)
    127 dB (2 V RMS, Stereo)
    THD+N: 0.0004%
    Differential Current Output: 7.8 mA p-p
    8 Oversampling Digital Filter:
    Stop-Band Attenuation: –130 dB
    Pass-Band Ripple: 0.00001 dB
    Sampling Frequency: 10 kHz to 200 kHz
    System Clock: 128, 192, 256, 384, 512, or 768 fS With Autodetect
    Accepts 16- and 24-Bit Audio Data
    PCM Data Formats: Standard, I2S, and Left-Justified
    Optional Interface Available to External Digital Filter or DSP
    Digital De-Emphasis
    Digital Filter Rolloff: Sharp or Slow
    Soft Mute
    Zero Flag
    Dual-Supply Operation:
    5-V Analog, 3.3-V Digital
    5-V Tolerant Digital Inputs
    Small 28-Lead SSOP Package
    APPLICATIONS
    A/V Receivers
    DVD Players
    Musical Instruments
    HDTV Receivers
    Car Audio Systems
    Digital Multitrack Recorders
    Other Applications Requiring 24-Bit Audio

    see that's what I think.. these 8 channel dac's are consumer product grade... there probably not going to be much better than an average soundcard I think, in the end your just going to be building a soundcard.... I guess that could be a good thing though, cause you can still control the rest of the op amps & caps & board design, but in the end I don't think these are audiophile grade, there made to go in dvd players & portable little things... consumer grade...
    Turbocad I fully agree with you. Anytime you get something pre-packaged, you don't exactly get what you want. Since we are not trying to compromise, but want the best or control over the best, then multiple 2 channel dacs are the way to go.

    I2S is designed to go between chips, so it will only travel a few inches.
    Cool. Now the question is that can one of your USB to IS2 chips commmunicate to mutliple dac chips? I think turbocad is right, we might be building a soundcard if we need a processor to go between the USB/I2S chip and the DAC chips. Hopefully we don;t need a processor since we only need routing, not processing. Processing is a link in the change of audio that is not needed since the computer CPU is going to do the processing. I think we need to contact an expert on USB DAC design to see if it's possible to route signals with any USB to I2S Chips. I'll look into this a little myself but I am a total newbie on DAC design.

  6. #196
    Car Audio Moderator durwood's Avatar
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    Yatzee!

    Felix-good finds on the USB chips. The only one I see that works for us so far,

    The Edirol UA-1EX uses the TUSB3200 chip and also does 24/96.
    See what I found on the data sheet.

    DMA Controller
    Four DMA channels to support streaming USB audio data to/from the CODEC Port Interface
    Each channel can support a single USB isochronous endpoint
    For I 2 S modes, either a single or multiple USB isochronous endpoints can be used to support multiple DACs/ADCs
    So here is what I envision:

    TUSB3200 -> PCM1794 -> opamps.
    USB interface to I2S (Supports max of 8 audio channels)->high dynamic range stereo DAC chips->swappable opamps to tailor sound and boost output voltage.

  7. #197
    Constant Bitrate
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    Quote Originally Posted by durwood View Post
    Yatzee!

    Felix-good finds on the USB chips. The only one I see that works for us so far,



    See what I found on the data sheet.



    So here is what I envision:

    TUSB3200 -> PCM1794 -> opamps.
    USB interface to I2S (Supports max of 8 audio channels)->high dynamic range stereo DAC chips->swappable opamps to tailor sound and boost output voltage.
    i want one....
    sounds like a fun project....
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  8. #198
    Constant Bitrate Felix509's Avatar
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    Good Mornin' time to check the fastest thread in the West, or is it East..

    I have to agree that the TUSB3200 and the PCM1794 would be a very good combo, great looking specs and they are both highly thought of in the internet forum world..

    Here is a product very close to what is desired, the HippoHIFI 'BLOAT' DAC.. It uses the PCM1794 and also has socketed OPamps. (www.hippohifi.com) I have contemplated buying one of these just for my computer/headphone listening.(under $200)

    The Bloat uses a PCM2707 digital receiver chip, so it is limited to 16/48, it also uses the 2707 internal buffer to reduce the I2S stream jitter. Maybe this fellow could design a board with multiple 1794 DAC chips and 4 USB recievers.

    If I understand correctly, the PCM2707 USB audio chip is 'plug and play' and uses windows drivers.

    The TUSB3200 is supposedly much better although it needs drivers written for windows and also need firmware coded for the chip itself. I know nothing of coding a chip, but i imagine you would need to know what you were doing..

    If the TUSB3200 chip was used and a special driver was written to support multiple instances of the same chip, maybe then all processing could be done in the software, then stream via ASIO to the individual channels on the different chips.

    Sounds good to me!!

    LATERS!

  9. #199
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    seems like this thread has gone from 8 outputs to the desire to only find 5.1 or 7.1 solutions?
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  10. #200
    MySQL Error scott_fx's Avatar
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    isn't "7.1" really 8 outputs? or do you want stereo sub outputs? wouldn't you be fine with 6.1 if they had it? 6 chans for your mid/tweet/woofer and one chan for the sub(s).
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