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MDAC First Listen (Part 00101001)

Discussion in 'audio' started by JohnW, Aug 12, 2015.

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  1. Dodeth

    Dodeth pfm Member

    Payment sent John.

  2. Superior

    Superior pfm Member

    Development paid :D
  3. ag66

    ag66 Member

    Payment sent.

    I currently use a Schiit Wyrd between my Aries and MDAC. I personally think it makes a difference and sounds better, but hope the Detox can make things even better.
  4. traf

    traf pfm Member

    Dev pymt sent John

  5. iansr

    iansr pfm Member

    I've ordered one slave unit. However I might want to have a 3 way active crossover configuration, so I'd need a second slave unit. But one of them would only be for bass frequencies and I think that would be over the top - I'd prefer a cheaper solution like this:

    If I got one of these instead of a second slave unit would I be able to daisy chain it in the same way and could I control its output volume in the same way from the master unit? In short, could I just use it as a drop-in substitute for a slave unit?
  6. Richard Kimber

    Richard Kimber pfm Member

    Yes I couldn't understand that either.

    - Richard.
  7. amershamman

    amershamman pfm Member

    Hi John
    I'd be interested in buying into this new venture. But can I pay around the middle of next week? Also, as a music first, technology second sort of person, could you describe what sound improvements I could expect? More analogue-like?
    Thanks, Chris
  8. timola

    timola pfm Member

    Hi JohnW,

    I'm in for the USB Detox.....payed my development fee just now....I'm one of the skeptics, but with an open I hope to be pleasantly surprised.... Thanks for such an interesting discussion, its all beyond me but not many others here...maybe I should start studying again!..enjoying the back seat ride on this pun intended.
  9. jadidih101

    jadidih101 pfm Member


    Just a request. So that we are taking the guess work out of USB cable choice and since you have equipment that can measure the differences, would it be possible for you to supply or recommend a 30 cm USB cable to go from the Detox box to the MDAC/FDAC?

    I can understand if you would not want to since it is such a small item but I thought I ask. Would be more than happy to pay extra for the work/material.

  10. Ciunas Audio

    Ciunas Audio Trade: Ciunas Audio

    From here:
    "Rise and fall time measurements for USB compliance
    Mandate: Required
    Effective Date: August, 2007
    There has always been a problem accurately measuring rise and fall times, especially on high speed devices. The measurement of interest is the edge rate, or slew rate, during the state change time. To help improve accuracy of the measurement, the USB-IF is standardizing on one test fixture for high-speed signal quality.

    Aside from the fixturing and probes used to take the measurements, major contributors to the inaccuracies in these measurements are the shape of the edge, noise on the signal and the method of calculating the 10% and 90% points as defined in Sections and of the USB 2.0 Specification.

    A waveform with slow corners (see sample eye diagram below) will result in a measured rise time that is slower than the actual edge rate would indicate. Also a small change in the position of the 10% and 90% points due to noise on the signal, etc., can cause a relatively large change in the measured rise time."

    USB 2.0 HS defines the fastest edge rate crossing speed as 100ps with a warning given for 300ps so any edge rates faster than 100ps will fail but it doesn't mention the slowest edge rate but the maximum interpacket delay times give an idea of this "So the maximum interpacket delay of a host's response to a device is <= 264 bit times + 60ns, which equates to 610ns or 292 bit times."
  11. fusion5

    fusion5 on the dark side of hifi...


    Wow, that's very generous! Thank you very much!

    I've paid for the 2nd Detox.
  12. mlf

    mlf Member

    Development paid.
  13. MattN

    MattN pfm Member

    Ditto, I'm in for the Detox box ;) Development paid
  14. fred sonnen

    fred sonnen pfm Member

    You lost me and I past the beginning of this discussion. ... could you please explain what tool you are talking about..... Thank you

  15. peterzz

    peterzz pfm Member

    Ooh, measurements. Are the other dimensions known too? I've been assuming full width to mean 45cm, but I need to know the height and clearance it required, or rather if 16cm or so will do.
  16. JohnW

    JohnW pfm member

    The FDAC is 430mm wide, 70mm High and 300mm to 320mm Deep.
  17. iansr

    iansr pfm Member

    430mm ! It's too wide John!

    Just messin' with ya:D
  18. JohnW

    JohnW pfm member

    I should be able to supply "approved" cables, I'll be in HK for the HKTDC electronics show in October and I can search for suitable vendors.

    Incidentally, I'd like to believe we will be looking to start shipping the units towards the end of October - at least I'll be able to hand build a few units for evaluation and test by PFM members.
  19. clivem2

    clivem2 pfm Member

    Don't be too surprised if solid connectors sound preferable to a short cable. This would likely require fashioning a support under the Detox.
  20. JohnW

    JohnW pfm member

    Thats fine - its only the development payment at this time.

    Typically RF tends to harden the sound and add a "Glassy" sharpness and sibilance which we tend to associate these "signatures" as sounding "Digital".

    The lower Jitter tends to widened the Left / Right sound stage while firming up the systems low end, but how USB Frame packet jitter impacts the sound is very dependent on the System / DAC.

    What the Detox will do remains to be "heard" :) But at least I can be sure we have given the MDAC / FDAC the best quality USB signal - and in the case of the MDAC, a galvanically isolated USB port.

    The USB 1.1 port with its galvanic isolation will reduce "background" noise and hum loops if present in the system when connected to the PC or when the Laptop is connected to its AC mains adaptor.

    I believe that when the Spread spectrum decorrelator mode is enabled the system will lose an extra layer of hardness and sound more "Organic / Analogue".

    Sorry if this sounds very vague and "HiFi babel" - but when you hear the effect for yourself then you will understand what I'm trying to describe.
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