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MDAC First Listen (part 00111001)

Discussion in 'audio' started by ti33er, Sep 12, 2017.

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  1. JohnW

    JohnW pfm member

    From the Ministreamer Chassis vendor:-

    "we have measured, the accuracy is within + - 0.3mm, should have no problem this time.
    If OK, we will arrange the shipment tomorrow (Chinese time)."

    https://www.dropbox.com/s/gully37xz4pcahs/Rev2 Ministreamer panels.jpg?dl=0

    So the chassis should be shipped tomorrow :)

    I've encountered an unexpected issue with the DevDAC PCB, a reel of components sourced from Asia is unusable - the end terminations of the components (component legs) have corroded with a thick BLACK oxide layer!!! making then unsolderable. I've just ordered a replacement reel from the UK that should be here tomorrow.

    The reel cost over GPB1000 :( and needless to say we cannot reclaim the cost of the bad reel from China :(

    Under the microscope you can really see how badly they have oxidised - I've never seen components this bad before.

    In the picture you can see I've scrapped the oxide off one of the components - also a 0.5mm lead Pencil tip for scale!

    https://www.dropbox.com/s/ytch71qej5hrhng/Clock Diode Oxide.jpg?dl=0
  2. JohnW

    JohnW pfm member

    The first few development systems will be shipped out this week - MDAC2 DD2A (the Hi-End MDAC2 versions) will start shipping in Q1 - we will Email everyone when we are ready to move to production.
  3. JohnW

    JohnW pfm member


  4. cckuan

    cckuan Member

    Hi John I have also joined the MDAC2 project for quite some time as well and good to learn we are now making some progress. Unfortunately recently my MDAC had the no comms error msg and wasn't working even after the crystal replacement. On closer inspection it turns out quite a few power supply capacitors as well as the smaller capacitors in the main PCB had all bulged. What sorts of options have I now got with the unit? Can I send this over for inspection and repair? Tks and look forward to further updates on the MDAC2.
  5. JohnW

    JohnW pfm member

    Yes, just send it over - I do have a backlog of 3 MDAC's here waiting to be repaired....
    cckuan likes this.
  6. kon5t

    kon5t New Member

    I just recapped mine, what a pain in the behind that was..... sounds great now though. What caps are you using?
  7. misterdog

    misterdog Not the canine kind

    Audiolab will replace the caps. FOC.
  8. hluga

    hluga pfm Member

    Thanks ! now downloaded and printed.

    I'm not sure to understand: there is no code for commands ?
    For example for doing
    Do we have to send it as plain text to the device or as a 4 bytes message ? (it's my first time dealing with such serial I/O)
  9. cckuan

    cckuan Member

    Tks John can you PM me your postal address as well?
  10. JohnW

    JohnW pfm member

    Plain text - Ill confirm with Jarek once he resurfaces...
  11. jadidih101

    jadidih101 pfm Member


    Sorry when you have a chance can you answer my question regarding volume control on DEVDAC+Streamer? Will I need a pre-amp for that?

  12. hluga

    hluga pfm Member

    According to the DEVDAC specs it is able to control the volume. (see my previous question). However someone has to develop the software for that functionnality.
    I have made some advance concerning adapting some parts of moodeaudio (interface, dio php module) on my rasp pi 2 to do such thing but i cant go further until i can put hands on the hardware. It's very hard for me to develop without the ability to test.

    If it works as expected i can deliver a version rapidly with a limited set of features (Filter,volume, source). Then i will work on the way to get feedback from the DAC.
    I can also design a simple control panel over raspbian able to control the dac without streamer features. The main problem is the harmonious integration into moode to be able to provide with patches for future versions.

  13. jadidih101

    jadidih101 pfm Member

    Thanks for your reply.

    So, I guess until we have the feature worked out we will have to use some form of pre-amp. This is fine. I just wanted to know what to expect.

  14. JohnW

    JohnW pfm member

    I'll try to ship with a version of software with volume control - at the end of the day its purely down to software.
  15. fred sonnen

    fred sonnen pfm Member

    I do not understand why do you have to pay for hardware which is unusable
  16. davidjt

    davidjt pfm Member

    Presumably there is no suitable solvent which removes oxidization without damaging the component?
  17. jadidih101

    jadidih101 pfm Member

    Thanks John. It would be great to have volume control but please don't bother if it would mean any delay to the boards shipment. We can figure it out once we have the boards. Hluga seems to have started already on this.

    To be safe I will use a pre-amp to start with just to be on the safe side until software method is thoroughly tested.

  18. JohnW

    JohnW pfm member

    There is no such thing as refunds when it comes to China - besides we have had these components here for about 6 months (they are common to MDAC2 PCB's etc).

    I've never seen such bad corrosion - so never considered to check.
  19. JohnW

    JohnW pfm member

    Its always going to be safer to use a Pre-Amp when testing development software to prevent damage to your system if theirs a bug...
  20. JohnW

    JohnW pfm member

    Not that I'm aware off - the parts come on "tape and Reel" to allow them to be feed into the SMD machine - theres no way to get to the components to clean them (if it where possible) without removing them from the Tape - then they cannot be placed by machine and they are really really Tiny - 1.6mm x 0.7mm so VERY hard to work with.
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