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MDAC first listen (part IV)

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

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  1. liszt

    liszt Active Member

    You can make a point without being obnoxious.

    I know what my ears hear. So did many people in this thread, who experienced some sound degradation due to excess digital attenuation.

    The fatal flaw in your assumption is that everything else in the signal
    chain behaves perfectly. Which has never been the case.
  2. janerik

    janerik Apodized

    Hi John, thanks for the quick reply.

    From your first sugestion, I've now got "Audiolab no comms".

    Now what??

    (I'm in Montreal)


  3. travelfotografe

    travelfotografe pfm Member

    Hi John,

    For serious listening sessions, I find myself listening at -30dB for "loud/compressed" commercial music/song recordings, -30dB to -24dB for better commercial recordings, and as high as -18dB for audiophile/classical recordings.

    For background music, it will be between -30dB to -40dB, but since it is background, I am not too concerned.

    If you still recommend -10dB attenuators, and since I am on the order list for the M-PAX, should I not just wait for the M-PAX and use its built-in attenuators?

    BTW, my power amp is a Rotel RB-1582 with input sensitivity/impedance/gain rated at 1.9V/12kOhms/26.5dB into B&W 804D rated at 90dB spl (2.83V, 1m)

    Thanks for your replies,

  4. Plutox

    Plutox Registered Abuser

    30dB is not excessive digital attenuation, particularly if that is what is required to achieve a low, night time listening level (which was the original enquiry way back).
    If -30dB / -40dB still results in a level that blows your head off, there is a case for analogue attenuation. But if that amount of attenuation achieves a "night time" level then any degradation due to the action of the attenuator will be so far below the threshold of hearing as not to matter.

    Obviously I have no idea what constitutes your interpretation of "night time" level but for most people this is probably 60 to 70dBa. It is quite likely that a sound level of this order will give the impression of bass lightness due to the nature of human hearing as indicated by the equal loudness curves but the effect is not related to the operation of the digital attenuator itself - it's merely the result of listening quietly.
  5. JohnW

    JohnW pfm member

    Hi Jan,

    Appears your unit has lost its software (which is the second unit this has happened too).

    Hoping you have a PC to hand (better if its running Windows XP)?, if you do can you PM your Email address and a contact phone number, and I'll Email you the files,then I can call you and talk you though the process to re install the software.

  6. elnero

    elnero pfm Member

    Make that 3, a friend/co-worker bought one that had that problem as well. I believe he sent his back to the distributor. Any idea why this is happening?
  7. janerik

    janerik Apodized

    Hi John

    Your inbox is full, so :

    janerik at bell dot net

    I have Win XP

    Fingers crossed

  8. Leprish

    Leprish Member

    The problem I speak of is specific to a sampling rate of 88.2KHz and was discussed in an earlier part of this thread. It was John, not me, who indicated that the problem would be addressed via the firmware update.

    Re the use of USB. This isn't possible because of a bug that Apple apparently introduced when they updated the firmware last October for the mid 2011 Mac mini and MacBook Air. Again, it was John and Dominic, not me, who indicated the problem with computer USB. Dominic even submitted a post describing what was happening with USB. With this info in hand I was able to convince Apple to swap out the logic board on the Mac mini. Sadly it had absolutely no effect on either the optical or USB input problems.

    With above two issues taken together I have limited options available to me for high res playback. To be frank, I'm not happy, but there doesn't seem a lot that I can do until (a) I hear what impact the firmware update has on optical port, and (b) await Apple fixing a USB port bug they seem not to be aware of.
  9. McKMini

    McKMini pfm Member

    Got a pleasant phone call today to say I should have my hands on an M-DAC this time next week! Yeah.
  10. EIffel

    EIffel Cereal Killer

    Lucky you as I'm waiting since mid December for my M-DAC to be replaced (output relay failure after just a few days, or so it seems), and was told yesterday by my reseller that I may get a new unit in March... :-(
  11. JohnW

    JohnW pfm member

    For your MAC USB issue you could try connecting via a USB2.0 hub, I suspect this will solve your issue.

  12. JohnW

    JohnW pfm member

    Are you still using your MDAC, or did you send it back?

  13. Leprish

    Leprish Member

    Sadly, it doesn't. I've tried both powered and unpowered USB 2.0 hubs from various vendors, none help. Basically, after a few minutes use the crackles and pops begin and get steadily worse. Strangely, this only occurs with hi res material (i.e. 88.2 KHz and 96KHz).
  14. EIffel

    EIffel Cereal Killer


    I've been MDAC-less since mid-December. Fortunately, I can use my Theta DSPro IIIa while waiting.

    I just hope that the replacement MDAC will arrive before the MPAX...
  15. mark.king

    mark.king pfm Member

    How does the mdac lose its software? When the new sw comes out can we have instructions on how to recover a unit when it does this please. I don't change equipment that often and often have hi fi for 10 years. I would hate to lose the software just after the gaurentee runs out or even a fe years after. Thanks
  16. JohnW

    JohnW pfm member

    Only one unit so far has been confirm to have lost its software, Jan's unit appears to be a different issue.

    Only by freezing below -20Deg C can the software be lost... however it can be restored by the user with the soon to be released upgrade software package.

    ATM we are at a loss to explain the single confirm case of software loss, but we are keeping an eye on the issue - however any future cases can be restored with the pending software update by the owner.

    There is one possible scenario that we can imagine (however unlikely)- and it will be removed in the pending software update.

    A very early beta release will be ready at the end of this week to help us diagnose the locking issues with DTV / Cable etc. If the locking issue is resolved (as we believe it well be), then we can release a "proper" build.
  17. JohnW

    JohnW pfm member

    Where are you based?
  18. JohnW

    JohnW pfm member

    The pending software release will indicate incomplete USB transmission packets IF this is the issue with your Apple.
  19. arthur

    arthur Banned

    Ok all. I have conceded defeat in the mighty world-wide search for four resistor xlr attenuators.

    It seems they are a non breed, not simply extinct. Even the pro side came up limp.

    Why do my damned Adams have such a whopping gain???

    Any one know the gain on a pair of Unity Rocks? I've been meaning to try them anyway, though I do wish I could afford the Boulder. Looks a mega beast.
  20. JohnW

    JohnW pfm member


    I've got your attenuators - how much attenuation do you want?

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