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CD Quality Audio — Parallax Forums

CD Quality Audio

drazmodrazmo Posts: 21
edited 2008-08-06 05:00 in Propeller 1
I would like to create a CD Quality Audio player. The goal is to play 16-bit 44.1KHz wave files from an SD Card. I have been using Raymond Allen' asm wav player and Micah Dowty SPDIF object. The SPDIF code sounds great since its just sending the data to the receiver and the receiver handles all the DAC functions. The asm wav player sounds good....but is not the same quality as when using the SPDIF or CD. It seems to be muffled in comparison. I am using the ProDemo board which has the Maxim headphone amp. If I were to add a DAC such as the TDA1543 would I be closer to the CD quality audio? Any other DAC preferably in DIP package?

Comments

  • Oldbitcollector (Jeff)Oldbitcollector (Jeff) Posts: 8,091
    edited 2008-08-05 14:21
    May I add to this question? Is there a chip that will take the SPDIF signal and output a standard audio signal?

    OBC

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  • lonesocklonesock Posts: 917
    edited 2008-08-05 14:43
    On the schematic for the demo board, I see the RC low-pass filter has values of 10k ohms and 10 nF. If my math is right that is a corner frequency of about 1.5 kHz, which will definitely kill the high frequency content of your audio signal. I believe the hydra put the corner frequency at about 4 kHz. On my protoboard I used a 750 ohm and a .01uF (~21kHz), and the output sounds pretty clean. Note that with an 80 MHz clock and a sample rate of 44.1kHz, the DAC is only approximately 12-bit.

    edit: so, the answer is "yes, adding a DAC is necessary to get to CD quality" [noparse][[/noparse]8^)

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    lonesock
    Piranha are people too.

    Post Edited (lonesock) : 8/5/2008 2:50:56 PM GMT
  • Forest GodfreyForest Godfrey Posts: 38
    edited 2008-08-05 15:43
    I am working on a similar project (8 channels of CD quality audio) using an AD1851 DAC.· It comes·in a 16 pin DIP package (among other available packages).

    I've got a problem with hiss, but I think that's due to poor output cabling and unstable power (both of which I'm still debugging).
  • drazmodrazmo Posts: 21
    edited 2008-08-05 17:42
    Oldbitcollector said...
    May I add to this question? Is there a chip that will take the SPDIF signal and output a standard audio signal?

    OBC


    The CS8412 will decode a SPDIF signal and with a DAC output a standard audio signal...... Here is a project using that setup

    http://www.dddac.de/ma_dac21.htm

    You can find a circuit at the bottom
  • scanlimescanlime Posts: 106
    edited 2008-08-06 05:00
    drazmo said...
    Oldbitcollector said...
    May I add to this question? Is there a chip that will take the SPDIF signal and output a standard audio signal?

    OBC


    The CS8412 will decode a SPDIF signal and with a DAC output a standard audio signal...... Here is a project using that setup

    http://www.dddac.de/ma_dac21.htm

    You can find a circuit at the bottom

    Wow, those DACs stacked in parallel are pretty hardcore [noparse]:)[/noparse]

    SPDIF might be a good solution if you can find a cheap single-chip SPDIF to analog converter, but a CS8412 + DAC seems kind of overkill. If you can spare a couple extra pins, it might be worth using a DAC that supports I2S:

    en.wikipedia.org/wiki/I%C2%B2S

    --Micah
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