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MDAC first listen (part II)

Discussion in 'audio' started by mark.king, Nov 24, 2011.

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  1. mark.king

    mark.king pfm Member

    Where does latency come into this for playback? I have a home studio and latency is a big issue but only for recording. I play an electronic drum kit triggering a program on my pc over midi. Now I need a latency of around 5ms to make sure the drums feel immediate.
    The same goes for any virtual instrument or if you want to monitor what your recording in real time. I can't see any device needing a full minute. A good half second provides totally glitchless sound (5ms does on mine so thats 100 times more)
     
  2. Plutox

    Plutox Registered Abuser

    Something to do with damping in the phase locked loop filter - it provides immunity to short term perturbations while successfully tracking long term drift such as equipment warm up.
     
  3. mark.king

    mark.king pfm Member

    Crikey computers are just not as good as I thought they were if it can take a full minute to sort the 1's and 0's out :rolleyes:
     
  4. Plutox

    Plutox Registered Abuser

    You get it if you use a big buffer to provide immunity to perturbations in the incoming signal. JW will need to answer this one I think - it would seem that the use of a second or so of buffer ought to provide a DAC (any DAC) with almost total immunity from clock perturbations in the incoming stream. Given that the cost of such memory is quite modest these days, it begs the question why this technique is not seen more frequently.

    To clarify, the 1 minute I quoted is for the receiving device to lock to an incoming stream. Connect the stream to the receiver, it takes a minute or so until the "lock" indicator stops flashing and says "ready" during which period the receiver's clock has acquired a really stable lock onto the incoming stream. Sorry if this was less than clear before.
     
  5. ChrisPa

    ChrisPa pfm Member

    There's a difference between short term variations (less than each sample period) ie. jitter, long term variations (over many minutes or more) ie drift, and something in the middle (say several sample periods) - not sure that there's a name for this last one but in the olden days it would probably have been called 'wow & flutter'

    We don't care about drift (the long term stability of your watch)
    Medium variations are highly unlikely & can prob be ignored)
    We are care about jitter

    The nature of the jitter (its spectrum) will also determine whether i'ts audible and what it sounds like
     
  6. Tenson

    Tenson Trade: AudioSmile

    Sounds exactly like my Lynx card when in 'SyncroLock' mode. It take over a minute sometimes to analyse the clock signal and lock on. Before that happens it uses a standard wideband PLL.
     
  7. 0rangutan

    0rangutan pfm Member

    JohnW, should it be possible to use the balanced outputs of the MDAC with a set of balanced headphones (ie. terminated in two XLRs)?
    Thanks
     
  8. JohnW

    JohnW Trade: Lakewest

    Yes, in fact someone has already done this on a HeadFi thread.
     
  9. russel

    russel ./_dazed_and_confused

    All I get if I do that is "failed to initialise audio stream" the only one that works is Audiolab MDAC stereo (IEC958) but that is obviously pulseaudio as it is still locked to 96KHz.
     
  10. dtd

    dtd pfm Member

    Did you select the custom output device mode, and type in the plughw:1,0 ? Sorry to sound so ... blunt.
     
  11. russel

    russel ./_dazed_and_confused

    Yes. I missed the question mark and what came after it. :)
     
  12. 0rangutan

    0rangutan pfm Member

    Thanks John - just found the thread now.
     
  13. JemHayward

    JemHayward pfm Member

    Vinyl into MDAC:
    I've just had my first listen to my turntable (Linn LP12, ARO, Zu DL-103) via the MDAC and it sounds very fine indeed. I'm using an EMU 404 USB as a standalone 24/96 ADC and it works extremely well. Maybe not too kind to surface noise, but I need to play with input levels a bit more, and the unit itself is crying out for tweaking but out of the box, it's pretty amazing.
     
  14. dtd

    dtd pfm Member

    Next thing to do would simply be running the command 'aplay -L' which should list where it thinks the MDAC's IEC958 handle is, then somehow decoding that to the relevant ALSA output. When my onboard soundcard (yuck) was active, it would cause a re-order of device enumeration.
     
  15. mavwong

    mavwong pfm Member

    Thanks for the feedback, now it's time to check with my pocket :)

     
  16. liszt

    liszt Active Member

    @JohnW:

    John, maybe you missed my post amongst the sea of replies here, so here goes again,
    " is it possible for me to get the mdac directly? I'm not in the UK but in asia and desperately need 2 units. If i leave this to my local audiolab dealer i'm going to have to wait until at least feb 2012, and that's being quite optimistic, me thinks. Any other possible channels? "
    Thanks
     
  17. Blurpapa

    Blurpapa Active Member

    +1! :)

    Edit: Have read the answer. Thanks JohnW
     
  18. Blurpapa

    Blurpapa Active Member


    Are you in Singapore liszt?
     
  19. JTC

    JTC PFM Villager...

    Anyone got both a CDQ and an MDAC and able to comment on how the headphone facility compares? I'm still wondering about an MDAC for use purely as a headphone/dac. Might seem a waste but it's still cheaper than the top-end Graham Slee which I had been considering at one point...
     
  20. Bob L

    Bob L pfm Member

    I am now very impressed with this little box. However, getting to this point has been very different from the experience in most of the reports which I have read. Until a couple of days ago, I had thought I would be sending it back, with some story about my ears/amplifier/speakers being different from everybody else’s. However, quite suddenly things changed. I have not kept an exact tally, but the following timings (a mixture of actual running with data input, and just leaving on) are roughly right, for my A-B comparisons against my old Musical Fidelity X-DAC V3 (upgraded to Level 2 by Audiocom), using mostly CDs.


    After 24hr:
    Rather disappointing. An unaccompanied choral recording is very 2-D, cardboard cut-outs rather than singers, in comparison with the MF. Similar with string quartet, but not quite so marked difference. First trials of piano recordings very disappointing- in comparison with the MF the sound is just wrong- my wife said “artificial”, to me it’s as if the sound has been taken apart and not reassembled correctly.

    After 48 hr, some improvement, not much, though the staging is getting better. Piano is still poor.

    After maybe 80hr, with larger groups of instruments or voices the SQ is probably equal to the MF, and the staging is better, but piano, and solo violin, are still not right.

    Somewhere around 90-100 hr all this undergoes a sudden transformation. The critical piano sound is now ahead of that from the MF, at least on DDD recordings. (So it’s not my ears after all….) However the older ADD transfers are still better handled by my old system- the effect of the M-DAC is a bit like removing the patina from an antique item of pewter- you can see the thing better, but the beauty has gone.

    Another 50 hr, and finally I hear what everybody is enthusing about- even ADD solo piano are ok (part of me still misses the bit of ‘patina’ which is still not there, but the gain in precision and staging more than balances this). In the more than 40 year old Barenboim-Zuckerman-DuPré Beethoven recordings I hear things from the strings which I didn’t know were there (and incidentally, I hear for the first time that the recording balance is off by 1.5dB for Op97!)

    I have not had the patience to read every entry, but has anybody else found the burn-in to be this slow? John, isn’t it a bit odd that there should be a fairly sharp change (I think within a couple of hours!)? I’d almost suspect a loose connection/dry joint, but there have been no signs of it wanting to go back to the previous ‘coarse’ sound.
    As you might have gathered, I've bought it, and many thanks to Acton Gate Audio for letting me have it on trial for such a long time!
     
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