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MDAC First Listen (part 00101110)

Discussion in 'audio' started by BigDog, Feb 24, 2016.

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  1. fred sonnen

    fred sonnen pfm Member

    the link @ DIYaudio
     
  2. JohnW

    JohnW pfm member

    Thanks Fred :)
     
  3. JohnW

    JohnW pfm member

    No, it will not damage the FDAC... I could always insert your IC for you....

    Do you want to order a PMD200? Jarek and I have decided to add an internal Daughter board "socket" that will allow us to design small PCB's to cater for such options as different hardware filters in the future - you can never tell whats coming around the corner in a few years - we want to keep the FDAC as flexible as possible. I have no desire to need to update the design in a few years - after 4 years working on the FDAC I never want to see a DAC design :)
     
  4. kennyh

    kennyh pfm Member

    Excellent John, thank you.

    PS The MDAC you sorted for me is superb, totally superb. Wish it wasn't so good as I'd order an FDAC. :D
     
  5. PhilCTTE

    PhilCTTE Senior mumbler

    That's the challenge isn't it .. To get it to work in your room. I guess the CLS needs more space to work because of its physical size. The cancelling effect of the rear waves could destroy soundstage also as well as reflection points ...but that does sound extreme to sound like a telephone headset :eek:

    Having separate subs gives you the flexibility to move them around the room to avoid certain issues and to have their own eq applied.

    Have a lot on at the moment with the listening room being extended, so not sure about the risk . And the summits just work :D
     
  6. PhilCTTE

    PhilCTTE Senior mumbler

    That's why I didn't hesitate ordering the FDAC after John had modified my MDAC to a fusion spec
     
  7. TimR

    TimR pfm Member

    Hmm... I'm tempted by this if someone else was interested (it's for 2 pc)

    http://www.aliexpress.com/item/PMD-200-HDCD-QFP100/32290824938.html

    but worried it might not be genuine, especially as it states "9998 lots available" !
    Is there any way to test it?
     
  8. misterdog

    misterdog Not the canine kind

    The Quad ESL panels have a fine fabric applied to the rear stator presumably to dampen the rear wave,and prevent the cancellation effect.
    So far as I am aware ML do not have such. Maybe try a diffusion panel behind the speakers.

    Some insight here.

    http://www.stereophile.com/content/sound-lab-1-electrostatic-loudspeaker-page-3#lktWqH3tR1dTr9wX.97

    My next project is to make new frames with mass damping as opposed to the flimsy/floppy factory version.
     
  9. kennyh

    kennyh pfm Member

    In all honesty I'd have ordered one Phil, but as the massive specs. grew I fear it'd be wasted on me. I'm USB from laptop and phono's to pre amp only. I'd use none of the other features sadly.
     
  10. efski

    efski pfm Member


    Lets wait for the FDAC little :)
     
  11. timola

    timola pfm Member

    Hi TimR, I'd be willing to join you in getting this PMD200 chip....please PM me on how to proceed....( I could send you 50% by paypal)

    I wonder if you could ship these straight to JohnW for testing and maybe for later installation into our units?
     
  12. TimR

    TimR pfm Member

  13. JohnW

    JohnW pfm member

    With the Aeons installed there was still alittle "Shoutyness" yet congested midrange so I made up a new pair of Balanced interconnects and they for sure reduced the problem - I also think I'm pushing the Power amps too far with the CLS's - I really need the VFETs now.

    I've jut installed a far more powerful computer in the Lab, as the laptop that was here before is unable to handle the Computer simulations I need to confirm some new ideas for the VFETs - I plan to spend 2 hours a day on the VFET design - I'd like to see these in "production" late summer or as soon as FDAC is complete.

    Well I just bought a S/H Rel Sub Woofer, but I suspect that the CLS's don't go deep enough in practice to integrate well, but lets see. At the very least the sub should be good with the Aeons.
     
  14. jirij

    jirij Virtual Member

    Except the computer! (Last time I was there.)

    TDAC ;)
    (or whatever it was called)
     
  15. Bob L

    Bob L pfm Member

    John, most of your boxes don't have to live with the house decor! Also, they are competently wired up......Misterdog, thanks for the rescue operation. Of course there isn't much information in the picture, though with careful inspection you should be able to pick out the screen of my MDAC. I agree that the Calex runs a bit warm, though in the lash-up version I only tried the finger test; the vertical panel above the terminal block was the hottest. Today I ran more careful tests with an IR thermometer, first with the lid on , so it's the case temperature. It started at 19C, reached 30C after 2hr., and 31C 90 minutes later. At the same times the MDAC front panel was at 27C and 32C, so given time the MDAC actually gets hotter. Taking the lid off, I measured maxima of 31C and 32C on the top surfaces of the two Calex units, and 47C and 46C on that panel above the terminals.
     
  16. scubaboy

    scubaboy pfm Member

    what REL did you order? I have been thinking of trying out a sub or two with my standmounts.
     
  17. mattgbell

    mattgbell Help the elderly and unwell!

    Cancellation due to reflection off the rear wall only occurs at lower frequencies. A fine fabric cover on the back of the panel will do nothing to absorb LF sound.

    In other words, cancellation due to rear reflections applies equally to Quad and ML designs.

    The best way to prevent cancellation is to nullify the reflections altogether, with a wodge of absorbent stuff on the rear wall. For an ML X-Stat panel (which goes down to about 350Hz) you would need a thickness of absorbent material of around 50cm (i.e. around half the wavelength of a 350Hz signal).

    EDIT This assumes of course that you haven't got the luxury of an enormous room, with the speakers pushed way out from the rear wall, in which case none of the above applies.
     
  18. Purité Audio

    Purité Audio Trade: Purite Audio

    Actually you need to absorb a quarter wavelength , and foam isn't particularly good in high pressure low velocity areas, you would really need membrane traps ,helmhotz resonators .
    Keith.
     
  19. timola

    timola pfm Member

  20. fusion5

    fusion5 on the dark side of hifi...

    Oh boy, another $200 for digital filters :D
     
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