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MDAC First Listen (part 00111000)

Discussion in 'audio' started by PhilCTTE, Jun 20, 2017.

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  1. JohnW

    JohnW pfm member


    The SHARC DSP's are at the mercy of the code implemented on them - so they will be as good or as bad as the software code.

    IIRC the SRC is block is built into the SHARC DSP's they dont need to be enabled, but I believe MiniDSP operate at a fixed sampling frequency (upsample or downsample) everything to 96KHz (atleast of there HDMI box) to avoid having to calculate different DSP filter coefficients for each sampling rate.

    I'm afraid its a case of MiniDSP not believing that the ASRC is so detrimental to the sound quality...

    DSP's are easy, its the software ecosystem around them that's difficult and MiniDSP has a an extensive software ecosystem. However, without being able to avoid the ASRC I'm not sure how much we can improve the SQ - for sure having better DAC's is a good thing, but the ASRC will remain the most severe bottle neck.
  2. iansr

    iansr pfm Member

    So to produce a leading edge DSP solution we need a top notch digital hardware engineer and someone who could write software for the SHARC modules. There's a guy called Jan Petřík who posts on DIYA and who fits the latter description. He happens to live in the Czech Republic. . . . . (and I have his email address) 😉
  3. JemHayward

    JemHayward pfm Member

    I think I will go for MDAC2 with streamer (even though I have a SBT already, I like the idea of built in streamer) - I will probably go on to FDAC when it becomes available, as the idea of revisiting DSP appeals.

    It then possibly means I won't actually need my Detox, as I won't be using USB input - but I'm sure I can find a use for it somewhere else!
  4. Lancastrian

    Lancastrian Well-Known Member


    This is my first post as I happened across this website and thread accidentally whilst looking at some Pink Triangle history online.

    I am currently looking at replacing my revered Pink Triangle Ordinal DAC and was considering an MDAC+. However, I also know that the Hi-Fi Collective do a resistor upgrade for the MDAC, using Charcroft slit foils. Would I be better therefore in purchasing an MDAC and look at the option of going to MDAC2 ?

    From what I have gleaned so far, I wouldn't need the streaming option, but would require optical SPDIF inputs.

    Thoughts gents, and JohnW.


  5. Ian M

    Ian M pfm Member

    :confused:I’m trying to give away my Detox investment. 500 views in the Classified section but nobody wants it.
  6. misterdog

    misterdog Not the canine kind

    Maybe they are all animal lovers ?

    I've lost all sense of whether I would benefit from a Detox/Streamer or full finger print panel..

    It's all led to my 3000 th. post. :eek:
  7. JohnW

    JohnW pfm member


    With the MDAC2 relativity close around the corner, don't bother with updating a standard MDAC with the resistors - the upgrade is expensive and will not deliver as good a result as the full MDAC2 upgrade.

    Really by FAR the best sonic performance option is the MDAC2 with discrete DAC, in fact I've called this option the Dacapo 25th Anniversary option - BUT it only works with USB, Streamer options - or with a CD transport that can be clock-locked to the MDAC2.

    Working on the MDAC2 Clock circuit this week, I have added a ASRC option as a "get me going" SPDIF input option for the Discrete DAC board - but I heavily frown upon "conventional" ASRC's...

    What do you need SPDIF input for?

    If a CD transport, then you can consider the Streamer board with 64GB memory option which allows you to rip almost 200 CD's into the streamers internal memory via a USB CDROM drive and then replay them Bit accurately - "Jitter Free" without needing to handle your CD's (with no lossy ASRC).

    If you have more then 200CD's then you can plug-in an external SSD drive and increase the storage capacity.... You can always replay from the CDROM drive "realtime" if we can find a "Silent" drive.

    If you liked your Pink Triangle, then the Discrete DAC option offers a big step improvement.
  8. JohnW

    JohnW pfm member


    Sad when something cannot be given away - I'll try to build your unit if funds allow, and once the production batch has been shipped I'm sure there will be more interest.
  9. JohnW

    JohnW pfm member

    Implementing the DSP hardware is nothing more then basic Lego blocks, there is very little hardware "skill" required - same with the actual DSP software - but what takes time is the UI front end - the top level user interface and ecosystem.

    Jarek can program the DSP's but we don't have the time to develop the necessary UI input - although we could easily hack a MiniDSP box...

    We will work on the DSP solution for FDAC, based upon a MDAC2(s) hacked to a MiniDSP box or some such via the MDAC2 Slave interface.
  10. jirij

    jirij Virtual Member

    you can set cdrom speeds in Linux (in the kernel driver, which is AFAIK used in case of USB drive as well).

    The command-line quick & dirty way would be via ie. "eject -x 4 /dev/sr0" for 4x speed (use -X to list all), the proper C-based way would be to use the CDROM_SELECT_SPEED ioctl (include linux/cdrom.h). You can use any device notification framework available (ie. udev) to do this upon drive plug-in or media insert. Feel free to pass this to the guys.

    Using this method, I've managed to tame many noisy drives that would spin up every 20 seconds only to spin down afterwards. :) Just make sure you have big enough buffers to last a few seconds for the ie. 4x speed CD to spin up and read a batch of data.

  11. Lancastrian

    Lancastrian Well-Known Member


    I use a Meridian 602 transport into my PT Ordinal, but require an optical input on my next DAC for the optical output from my Samsung TV. DVD/Blu-ray replay has the audio in advance of video due to the video signal processing in the TV so cannot use their audio outputs directly to the pre-amp.

    I can appreciate the higher quality of the discreet DAC's especially as I lusted for a DaCapo, but couldn't justify the 4 figure sum at the time.

    I have approaching 900 CD's at present.

    The PT Ordinal has been excellent, it was just a shame I wasn't able to acquire a 22 bit filter module for it.

  12. JohnW

    JohnW pfm member


    As the quality from the Samsung TV is never going to be the highest, using the ASRC will be fine for "TV" input.

    We can add Clock-Lock to your Meridian 602 transport to support the Discrete DAC- but really consider the streamer PCB, once you get to using it, I'm sure you will realise how useful it is and not go back to loading CD's for your daily music library...

    I'm old school and feel comfortable with the simplicity and security of CD, but the MDAC2 streamer ended up being so easy and practical I don't have a CD transport on hand these days...

    Which filter did you have fitted to your Ordinal?
  13. alloja

    alloja Well-Known Member


    Does this mean the FDAC cum DSP is going to be a two-box affair?

    Also, would the ASRC be the only way of bringing S/PDIF to the FDAC?
  14. Sibbers

    Sibbers pfm Member

    This is good to hear. I worry about using a 3rd party DSP without getting ahead of some of the issues they can cause. I'm assuming you mean a single box solution for FDAC, that's how I interpreted what you said anyway...
  15. JohnW

    JohnW pfm member

    As mentioned last week, today we have just released Streamer DEVDAC PCB files.

    https://www.dropbox.com/s/8h2tbw4jd9w6u9t/DevDAC A01.jpg?dl=0

    The DEVDAC connects to the MDAC2 streamer PCB allowing software development and testing of the streamer software (and also hardware) ahead of the MDAC2 mainboard release.

    The DEVDAC is based upon a pair of ES9038's and is fully balanced. The board also features a interface connector on the bottom RH side for the MDAC2 ADC development board.

    The DAC's USB connector is shared with the Streamer output - which is not ideal as the USB is enumerated / de-enumerated as the input source is cycled.

    We will also release a secondary USB daughter board to avoid this issue and allow the DEVDAC to be used as a USB / SPDIF input "standalone" DAC once the streamer PCB is transferred to the MDAC2.

    When we tested the Pro-Ject DAC it was sensitive to the quality of the external PSU - so we designed a far more advanced PSU on this PCB and its also fully balanced so "should" be sonically better sounding the Pro-Ject design.

    We also use differential clocks to the DAC's & synchronised the USB clock etc. to the Audio clock.

    Not sure if anyone interested in "playing" with the Streamer / DEVDAC... let me know and we will arrange the relevant number of early release PCB's to be built.
  16. timola

    timola pfm Member

    I'm not a good beta-tester as I wouldn't know what to do with a bare PCB dev-dac and streamer board. I would need a fully built unit (product) with an on/off button etc.etc. to compare it to my MDAC, so I can't really help out here.

    But if John doesn't get people who know what to do (or at least a bit more than me...I couldn't even open my MDAC..:mad:), I could have a go, but would need lots of instructions and support....no.1 would be which box/chassis could I put them in???...:confused::confused::confused: no.2 where is the 'on/off' switch!

    Can the people who know such 'stuff' please help out here... it will benefit people Like me greatly in the long-run.
  17. JohnW

    JohnW pfm member

  18. hluga

    hluga pfm Member


    I could be interested by testing devdac and streamer.
    BTW: I also need a pair of good amps (Waiting for VFETS) to upgrade my eclipse TD A 502.

  19. JohnW

    JohnW pfm member


    Its not so important that 3rd parts here test the streamer solution, its only really mentioned if any DIY fans are interested in building there own streamer / DAC based on these boards. I'm mindful that PFM is not really the forum for such advanced topics.

    The MDAC2 streamer solution has generated much interest within the industry so its getting a "thorough good workout" :) and being tested in many situations which is great feedback for us... this gives us ever increasing confidence in the MDAC2 streamer platform - at the end of the day with only 40 or so MDAC2 Streamer customers we will be a small tight knit community :)
  20. JohnW

    JohnW pfm member


    I'l put your name down then for one of the 6 PP streamer boards + DevDAC....

    Are the 8200MB's in my basement any good to you? they are alittle "bright" in standard form but plenty of bass control!
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