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MDAC first listen (part V)

Discussion in 'audio' started by Oktane, Mar 11, 2012.

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  1. EIffel

    EIffel Cereal Killer

    If going for a selected list of input labels (rather than free text, which would require writing more code), I'd offer the same options for all inputs including the USB one. This would be simpler and would allow people with SQBOX to use the USB input (for best results)... One day this may also come in handly for GAME boxes or SONOS too
     
  2. Gefilus

    Gefilus pfm Member

    How about a simple HW solution: A small (self made) plaque showing mapping of actual connected devices to current MDAC input names, fitted on a stand matched to MDAC finish :)

    It is (hopefully not only) me but I like the current generic input names.
     
  3. mark.king

    mark.king pfm Member

    Thanks for the answers on headphones. I don't want to buy another amp for headphones so the mdac looks to have killed two birds with one stone. Cheers
     
  4. JTC

    JTC Saint Alphonso!

    Mark, yes, the MDAC as a headphone amp works very well, and to be quite blunt I struggle to find any areas to find fault at all with the Mini-via-USB->MDAC->HD800 combination. I reckon from that point on it would simply be slight preferential differences rather than 'better' in any way, shape or form. I'm done!
     
  5. Chronic

    Chronic pfm Member


    I guess not then....

    Sods law after making this post my M-Dac wouldn't switch on last night :(
     
  6. JohnW

    JohnW Trade: Lakewest

    When its plugin into your PC - does the PC popup with unknown USB device?

    If you leave the MDAC powered up for say 1 minute does the display say "Comms Error" ?

    If yes to both then its a good chance your MDAC's lost its software - we can update via Email.
     
  7. Chronic

    Chronic pfm Member

    I'll have to check the USB thing when i get home John, it definitely didn't say 'comms error' though as i left it on for a while thinking it might kick into action as the 'audiolab' sign usually takes a few second to come on... tried switching on/off a few times to no avail

    i get the feeling ill go home today & it'll power up as usual, fingers crossed...

    thanks for the fast response
     
  8. JohnW

    JohnW Trade: Lakewest

    Needs to be left on for a minute or so...

    Dont worry, Ill sort you out - I promised a new mainboard awhile back...
     
  9. Nenox

    Nenox Member

    Hi,

    Just tried Triodes SBT usb hack with the m-dac.. Sweet :)

    One thing: My usb cable is super loose when inserted into the m-dac (loose as in swimming around). The connection seems stabile, but I never saw anything like this with USB cables/devices before.. Normal? Cause for worry?

    Cheers
     
  10. Chronic

    Chronic pfm Member

    its working fine again now, switches on as usual...
     
  11. simonom

    simonom pfm Member

    Mine is loose, too. Not "swimming around," but definitely loose in comparison to the usb socket into the computer and also in comparison to the other sockets at the back of the mdac. Works fine.
     
  12. Nenox

    Nenox Member

    Thanks a lot for that! And sorry about the grandiose prose - Clearly I lack the subtlety of an Englishman :) Anyhow, it is "swimming" though and unlike anything I've seen in USB before. Someone reported the USB port breaking and I need to make sure I don't have a bad unit as this is my last day within my return period.

    Thanks
     
  13. Ibbots

    Ibbots pfm Member

    The plastic bit in the middle of the usb socket of my mdac came out with the cable one time which was a surprise - glued back in with araldite and been fine since
     
  14. jmbulg

    jmbulg Member

    Sorry if already asked in the past:
    If I remember well the MDac has no output capacitor for DC decoupling. I am going to connect it directly to a hypex ncore which is DC coupled. If I understand correctly this can cause a problem if the DC offset is too high. But what is too high and how can I check before connecting ?
    Thanks
     
  15. JohnW

    JohnW Trade: Lakewest

    Hi jmbulg,

    On the grounds of ultimate sound quality (IMO there's no such thing a as good sounding capacitor) - the MDAC is direct coupled - with output DC trimmed to +/- 10mV, with a target of +/- 3mV.

    These levels are low, and should not cause problems - give it a try with a cheap speaker - I'd not expect problems.

    DC offset protect on the output of any Amplifier is always worthwhile ,

    John
     
  16. gh0st

    gh0st pfm Member

    jmbulg,
    If you have a multimeter you can measure the DC offset for yourself pretty easily, just turn everything on (no music playing, no speakers connected), set the amp's volume control to minimum if it has one, set your multimeter to it's lowest DCmV scale, and measure between the ground and the left/right outputs of your amp.

    I'm more familiar with headphones than speakers, but even headphone loads don't generally have a problem with 10-20mV, I would only be worried if it was 20mV+, and even then I don't believe that normal DC offset protection circuits will engage before 100mV or more.

    If you have a DMM, give it try. The DC offset from my MDAC is 6.5mV at the headphone output, and it's totally stable, which is a fine figure.

    ./dom
     
  17. highfi

    highfi pfm Member

    Finally coming round to thanking John Westlake for his help in re-uploading the software (firmware?) to my M-DAC after a rare (3 units out of 10,000?) occurrence of a "no comms" issue. Unit happily reproducing/recreating Stan Getz & the Oscar Peterson Quartet's heavenly sounds at the moment.

    I would also like to take the opportunity to praise a so far unsung feature: the screen frequency indication takes guesswork out of music track resolution/downsampling/upsampling issues and has been essential for my peace of mind - well done!
     
  18. highfi

    highfi pfm Member

    According to JohnW, "So as long as a decent AC mains filter is fitted to the "PC" and used with our optically isolated Async USB solution, any "PC system" will work as well."

    May I ask what a decent AC mains filter might be? No DIY solutions please, thank you.
     
  19. highfi

    highfi pfm Member

    Another quote by JohnW:
    "Yes, we could make a small box with a Clock-Lock Async 192kHz Isolated USB converter - I'd rather do this then design a "Olimex usb isolator" type product... It would resolve two issues with one stone... (Async USB 192 + Isolation)..."

    Any progress on that front, John? No transport required, thank you.
     
  20. highfi

    highfi pfm Member

    Last post for now, apologies for the rapid-fire succession:

    For consideration for the M-DAC software (firmware?) wishlist:

    - phase invert switch

    - mono switch
     
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