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MDAC first listen (part IV)

Discussion in 'audio' started by adamlau, Feb 5, 2012.

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  1. ChrisPa

    ChrisPa pfm Member



    You can test and measure this relatively easily (you can, you've got the measurement kit :) )

    - take 2 amp modules that you are intending to bridge and add (say) a 1ohm or 2ohm resistor in series with the output of each

    - connect a speaker to a single amp and measure the audio output - amplitude, phase, distortion etc.

    - bridge the 2 modules and measure again

    compare and contrast
  2. jonstatt

    jonstatt pfm Member

    Hi John,

    You mentioned very honestly, that you would be honest regarding the marketing of the M-PAX if you yourself, could or could not appreciate an audio improvement over the MDAC in its default offering. Have you already had a "lab" mock-up of an M-PAX that you have validated the improvement with, or is that dependent on your early prototypes later this month. Obviously you had a design in mind that should improve the audio quality, but I remember you being very transparent that you didn't know how big or small that difference would be.

  3. finesensations

    finesensations pfm Member

    Hi John

    Very happy with my current amp (HK980) as it drives my Yamaha NS1000Ms very well.

    That said, I may be unable to resist trying/buying one of your M-Amps with my M-DAC.

    ATM, I run one of the the tape out connections of my amp to my mini system in the kitchen.

    If I used an M-Amp, would it be possible to connect the M-DAC to the M-Amp via XLR and the RCA output of the M-DAC to my 'mini system, at the same time, without any compromise in SQ?

    I appreciate the M-DAC RCA output would not be fixed but I could set the mini system volume control accordingly.

    Look forward to you posting more details (and pics) of the M-Amp when available.
  4. einsnull_chris

    einsnull_chris New Member

    Hi John,

    I am just reviewing the MDAC and I am pretty happy with it. But there are some questions I have:
    What exactly is the D3E Decorrelator? What does it do? I am a little stuck right now.

  5. JohnW

    JohnW pfm member

    Hi ADL,

    I agree, I also hear differences when Bi-Wiring speakers - so your not alone.

    With Bi-wiring you separate the heavy Low Frequency Current path from the lower current High Frequency Path - effectively isolating the voltage drop within the cable.

    For the test to be valid, you would first have to try listening to the speakers still wired-up as "Non Bi-wired" but with the two sets of cables to each speaker (so the cables are paralleled) - this way you can confirm wither the effect you hear is due to simply Lower cable resistance - or due to separating the current paths (You would not need to separate the current paths if the cables had zero Resistance).

    The effect on sound quality can be pronounced (for better or worst) so I'm surprised when people still argue about the benefits (effects) of Bi-Wiring...

  6. JohnW

    JohnW pfm member

    Yes - We will add Trigger Output

    Sorry, No due to space limitations - the casework is too small (heatsink area) for 3 channels - we are already pushing the thermal limits for 2 channels.

    With Balanced XLR, the Audio Signal is separated from the Earth leakage currents and RF crud inevitably flowing though Chassis "Earth" - so this alone is worthwhile.

    the XLR can be wired for SE input - so you can still use a RCA connector at the other end of the Cable.

  7. JohnW

    JohnW pfm member

    :) Even better, when I'm back in China I can measure Qts & Qes of a Bass driver - Driven SE or Balanced, guess this would be the ultimate test (and I'd personally be very interested in the results).
  8. John_73

    John_73 pfm Member

    Keen to know more about D3E myself. According to the manual:

    "The D3E engine decorrelates fixed patterns within the data stream replacing them with data based on a probabilistic model. Data decorrelation reduces both Digital and Analogue second order effects within the DAC"

    Unfortunately I can find no English translation of this in the manual... ;)

    Also curious why there's a 'partial' supression option too? What exactly is being supressed - fixed data patterns?

    - John
  9. JohnW

    JohnW pfm member

    Hi Jonathan,

    So very true - I still have not listened to the PSU design - I have spent several weeks designing and simulating the just one section of the design - So I'm happy it will be a very good PSU! although I have little idea of its ultimate effect on SQ.

    The design is so complex that only a completed unit would be worthwhile listening too. I'm currently now working on a GBP200 DAC that has to be ready for the Munich Show... driving me mad.... I believe this little DAC will Kick some arse :D (But again - still not listen to it yet)

    Still, if the PSU does not improve the sound - at least the casework tooling will be ready for the M-AMP's, casework is the hardest aspect of the design / production for us....

    Works in progress...

  10. JohnW

    JohnW pfm member

    We are asked this Question often - and any effects will be system dependent (loading effects of cables and amplifier input lstage oading effects etc).

    The only answer is to try,

  11. Plutox

    Plutox Registered Abuser

    When a 24 bit converter is presented with 16 bit data, normally the least significant 8 bits are treated as null. I believe D3E is an attempt to improve upon this situation by correlating any bits for which real data does not exist, with the existing data and thereby hope that something more useful than either nothing or total randomness (i.e. pure noise) is added.

    Stated crudely, an attempt to synthesize the bits you don't have by taking an intelligent look at those you do!
  12. John_73

    John_73 pfm Member

    Sounds like something one should leave switched off then, if one wants to stay faithful to the original input data at least. Is this D3E similar to something like Pioneer's Legato Link system which attempted to 'guess' frequencies beyond the cut-off point of 16-bit?
  13. JohnW

    JohnW pfm member

    No don't worry, we are not trying to "recreate" any Data (we leave cheap tricks like that to MP3) - technically the DAC performs better (and IMO sounds better with D3E enabled).
  14. John_73

    John_73 pfm Member

    That's good to know John - but what exactly does it do though? Was PlutoX's explanation correct? I did read the MDACs manual but that left me ever more confused as to what it actually does lol!
  15. Carlos68

    Carlos68 pfm Member

    I agree, having tried it with and with out i find with D3E on i get a slightly fuller sound with a touch more bass extention, without it sounds a little lighter and thinner :)
  16. JohnW

    JohnW pfm member

    Hi John,

    We are forced to be deliberately coy about the inner workings of D3E (Digital Domain Deceleration) to protect our IP...

    Plutox has grasped the basic idea, however we are not trying to "recreate" any audio data - rather preserve the genuine Audio data during the conversion process.

  17. finesensations

    finesensations pfm Member

    I agree.

    I've settled on the OT DD filter.

    What filter(s) have you tried and what are you using now?
  18. JohnW

    JohnW pfm member

    Hi Chris,

    D3E operates on many levels, both in the Digital and Analogue domain.

    During the conversion process the audio data being processed directly modulates the DAC's internal PSU rails at die level (and thus the internal clock distribution = Jitter).

    D3E attempt's to Decorrelate first and second order effects of this substrate level modulation process - Its important to state that to preserve fidelity no Audio data is modified.

  19. JohnW

    JohnW pfm member

    The effects are subtle - but once you learn to recognise them they become obvious...

    To me, D3E has the effect of making the sound quality more "real" - open and smoother.

  20. bigmarcelo

    bigmarcelo pfm Member

    I have a pair of HD650 with Moon audio V3 silver cables and they sound great.... however, the pair which gets most use due to comfort, while listening in bed (and no sound likage) is my Bayers 770 ... soo comfortable....
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