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MDAC First Listen (part 00110010)

Discussion in 'audio' started by 44000khz, Aug 15, 2016.

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  1. adamdea

    adamdea You are not a sound quality evaluation device

    It depends how you want to do your conversion and in what stages. The existing mdac has an external AC supply and an internal PSU board. Even with an external DC supply there may be a need for further conversion.
  2. iansr

    iansr pfm Member

  3. adamdea

    adamdea You are not a sound quality evaluation device

    There are also other conversions to different dc levels, but I'm not sure whether these are done on the power board. Incidentally my recollection is that JW said the weak link in the mdac was it was in the low level supplies to the clock or the dac chip
  4. davidjt

    davidjt pfm Member

    Hard to guess without knowing what's inside the sealed case of the old psu. Is the output regulated at all?
  5. Bob L

    Bob L pfm Member

    No, it's just a dual wound (for digital and analogue supplies, so far as I understand it) step-down mains transformer. The regulation comes from the internal circuitry of the MDAC.
  6. davidjt

    davidjt pfm Member

    That's as I thought: my impression following our collective efforts is that step one is to keep AC outside the (MDAC) box.
  7. Sibbers

    Sibbers pfm Member

    Any verdict from hearing the result of the 'superior', yet? :)
  8. JohnW

    JohnW pfm member

    I'm sure the units still in shipping...
  9. Sibbers

    Sibbers pfm Member

    The anticipation is building! How's things with you John?
  10. JohnW

    JohnW pfm member

    Today (Sunday) I should receive the Detox Electronics quote... its going to be interesting!
  11. radamel

    radamel Music Fiend

    Let's hope for a good surprise!
  12. JohnW

    JohnW pfm member

    Oh MAN!!! first quote has come through and its totally random - some parts are more expensive then even DigiKey 100pcs pricing while others seem too good to be true :( This is going to be a royal pain...

    Still we have three other company's quoting - then I should be able to get a better handle on things...

    I have IAG pricing from 5 years ago so atleast I have a benchmark....
  13. JohnW

    JohnW pfm member


    You cannot use two separate DAC's per channel as there is no way of insuring the phase between two DAC's without Master Clock synchronization - hence the Clock link on the FDAC.

    We had Phase issues with the MDAC2 prototypes that used one DAC per channel (and same Master clock) on SPDIF signals - we had to resort to a few tricks to force rapid Phase Locking between DAC's (and Audio Channels).

    I can modify the Two DAC's we spoke about for Master / Slave clock locking.
  14. Discovery

    Discovery pfm Member

    While it's quiet, I noticed this recently...

    Bryston, US manufacturer of exotic hifi equipment, recently introduced an entry-level digital player into their range. Surprisingly, they make no secret of the fact that it's based on a Raspberry Pi 2 and a HifiBerry S/PDIF output board.

    Bryston certainly appear to take this hardware seriously:
  15. iansr

    iansr pfm Member

    Just to make sure you have full info, this is how my system is configured:
    Aries Streamer digital output - digital signal then split into 2 identical signals - one goes to "left" MiniDSP OpenDRC DI and the other goes to the "right" OpenDRC DI. The OpenDRC DIs process the left and right elements of the signals respectively and each DI outputs the 2 "channels" that are needed for each speaker. So one DI outputs the 2 digital signals needed for the 2 drivers in the left speaker and the other DI does the same for the right speaker. So each DI feeds a 2 channel DAC, hence the need for 2 DACs.

    I'd been given to understand that if I used 2 identical DACs that I would be OK and it never occurred to me that their outputs could be out of phase. Given this additional info do you still think there is a potential phase problem?
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