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MDAC First Listen (part 00110011)

Discussion in 'audio' started by adamdea, Nov 6, 2016.

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  1. adamdea

    adamdea You are not a sound quality evaluation device

    I wonder what exactly they have changed beyond the price.
  2. EIffel

    EIffel Cereal Killer

    There is a nice box, a display and a power supply... plus a lifetime warranty.
    The funny thing is that this isn't even based on the latest pi.

    I'm also wondering what software this runs... but all of this should be for another thread.
  3. sq225917

    sq225917 situation engineer

    Ian you have gain to burn via balanced outputs, why not just split the cable after the DAC. I use my mdac at minus 10db and about 1/10th of the volume of the bpbp.

    What exactly is it you want to achieve?
  4. JohnW

    JohnW pfm member

    Even with two identical DAC's there's nothing to guarantee the channels will be in-phase due to the internal PLL / ASRC locking arrangement - hence the Clock link on the FDAC.

    Its not easy to lock two DAC's on the same PCB with internal ASRC...
  5. iansr

    iansr pfm Member

    I've got 4 separate unique channels ( 2 per speaker) to convert from digital to analog, hence I need 2 x 2 channel DACs.
  6. iansr

    iansr pfm Member

    Ok - I'll send you a Skype message.
  7. ChrisPa

    ChrisPa pfm Member

    What were the adverse effects of this?
    (I'd have expected that the long term stability in each DAC, and therefore channel, was good rather than (say) sample to sample phase shifts. And therefore the effect should only have been like moving your head (very) slightly to one side.)
  8. sq225917

    sq225917 situation engineer

    Sounds like what you need is quad channel dsp and DAC in one clock locked device.
  9. iansr

    iansr pfm Member

    Already got 2 DSP devices and they are the only option for implementing the necessary crossover settings.
  10. JohnW

    JohnW pfm member


    On an early MDAC2 development board we looked at 20KHz FS signwaves on a scope for each channel (via SPDIF inputs) and you could see during a lock event that the channels would be out of phase with each other - drifting between each other (not a fixed phase error) - sometimes taking minutes to "Snape" into phase lock.... thats with a Single Master Clock to both DAC's - so without too much thought its easy to imagine the situation with separate non Clock Locked DAC's...

    The inter-channel locking Phase was VERY random... I recall early ASRC IC's used to have Sync pins to synchronise multi channel applications - the ESS devices dont have this feature.
  11. Rjpcardoso

    Rjpcardoso pfm Member

    Johnw as it's been so quite here, let me tease you with this amp. We saw it at the show and thought it was the vfets :eek:


    The amp sounded veryyy good but I am sure the Vfets will be better!
    Any developments on the projects recently?

  12. iansr

    iansr pfm Member

    I love the Industrial chic look of the heat sink.
  13. mrflibble

    mrflibble pfm Member

    Hi John

    M-DAC arrived back today safe and sound. Listening to it right now, sounding great again through Sennheiser HD650! Thanks very much for your time and trouble.

    Many thanks

  14. brab

    brab pfm Member

    I can send my sources to either the coax or optical inputs of the mdac. Is there any diffference in sq introduced by the mdac?
  15. JohnW

    JohnW pfm member

    I wanted to say that to you and Superior to give your unit a few days "run-in" period as you have a host of new Caps + extra organics, and to my ears they need to run-in...

    IIRC, you have V0.90 installed - it be interesting to see if you hear any difference with later software versions.... I prefer V0.90 (as a side note, you have the Detox version of V0.90 installed - it has the 12MHz output option in the "SPDIF output menu").
  16. JohnW

    JohnW pfm member


    We are waiting for the 6 Axis CNC machines to arrive to sample the VFET chassis - I loosely hoping to arrange (collect) while I'm in China for Detox production.
  17. JohnW

    JohnW pfm member

    For sure there will be, so try both options and see which sounds better in your system.
  18. JohnW

    JohnW pfm member

  19. ti33er

    ti33er pfm Member

    Hi John

    Are the 'MiniAmps' the 8200MB re-engineered? ...I'm a bit confused as to what these items are if not those?

  20. mrflibble

    mrflibble pfm Member

    Thanks John :)

    How many hours run-in do you recommend?

    Out of interest, what are the extra capacitors for?


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