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Thread: audio over USB v. optical

  1. #371
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    Nov 2010
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    Status?

    I havent seen anything about the status of this for a while, any news?

  2. #372
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    Oct 2007
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    Hey everybody,

    Sorry I havent updated in a while, I now have some time to start back on this project. Turns out that Via does not want to help out, so back to the drawing board. CEntrance wants $20K/license for asynchronous code, which I dont have, so I dont think thats the best route. I have no idea how to program that chip so I was thinking about something like this:
    -tusb2046 usb hub....(1)
    -pcm2707..............(4) usb-I2S (bypassing the internal dac)
    -pcm1798............(4) I2S-Current (dac)
    -ne5534............(24) I/V and summing opamps
    It wouldnt be asynchronous but if we can get something physical with whats been already tried and true, thats a step in the right direction. I know that you want interchangeable opamps, but just for proof of concept i want to use the TI recommended. Does anybody know of any issues with having the computer recognize 8 separate channels if a usb hub is used? If not, I am going to go ahead and order the parts and build a rough prototype to ensure that the sound card does what its supposed to do with regards to channel separation and decent output voltage.


    Look forward to hearing from you guys.

    Thanks
    -

  3. #373
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    Oct 2007
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    ---Update---

    Emailed Cmedia to see if any of their chips have the ability to handle the usb to I2S phase, which would allow us to get rid of the usb hub and the pcm2707. Ill let you know what they say. In the meantime, i am going to order the 1798s and the opamps as that portion of the design is not going to change.
    Ryan

  4. #374
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    Dec 2010
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    hey guys, how about altmustech USB to I2S module? Check it here: http://www.pcm63.com/?191,usb-to-i2s...e-for-diy-dacs

  5. #375
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    Oct 2007
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    Good find on the I2S module svgs, but I think I found the solution:

    The cmedia CM6620, this will go directly from usb to 8 I2S outs, which will then go directly to four pcm1798 or 1794. I plan on having interchangeable opamps for different sound preferences. The chip supplier is requiring that I purchase in lots of 600. Quite a bit investment at $10/chip, but I have an investor willing to fund the entire project. So I will get with him next week and the chips should be ready for shipment in about 5 weeks. From there, I will start prototyping and testing out different configurations. Thunea is willing to write custom software for the TA, xovers, and phase alignment. I also plan on having a headphone jack. Let me know if you see the need for anything else. Ill keep you updated as soon as I find out info.
    Thanks and have a great new year
    Ryan

  6. #376
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    Oct 2007
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    Turns out that chip will not work. I decided to go with the usb hub-->tusb3200-->dac design scheme. Now the only obstacle is hiring a programmer to write the code for the tusb3200a. If anyone has suggestions or knows anyone who could do it, please let me know.
    Thanks

  7. #377
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    Oct 2007
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    Beautiful: Usb--8 I2S channels


    http://www.diyaudio.com/forums/digit...interface.html

    now the fun part


    so for the output stage, we have a few options:

    opamps
    discrete
    tube

    any ideas?

    ---------- Post added at 01:26 PM ---------- Previous post was at 01:23 PM ----------

    Beautiful: Usb--8 I2S channels


    http://www.diyaudio.com/forums/digit...interface.html

    now the fun part


    for the output stage we have a few options:

    opamps

    discrete

    tube

    any ideas? advantages/disadvantages for each

    also there is a new 8 channel 32 bit dac available:

    http://www.esstech.com/index.php?p=products_DAC

    so there are also decisions that need to be made about the dacs/dac to be used...

    look forward to your suggestions/ comments

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