Chord Electronics - Blu Mk. 2 - The Official Thread

Discussion in 'High-end Audio Forum' started by ChordElectronics, Jan 5, 2017.
  1. Whazzzup
    I must interject as a lurker here but my streamer brought benefits to sq that no jitterbug and would suppose any number of ferrite could provide.

    Sup with Dave and blu2 that any remedy is necessary.
  2. Triode User
    Well, there is a very healthy discussion going on in a thread on Sound Science regarding USB cables where the measurists on there conclude that if a USB cable makes a difference to a DAC then the design of the DAC is flawed and that any competent DAC should be able to filter out RF and EMI noise on the USB input. I tried to enter the discussion but was basically dismissed with great scorn and derision especially when I suggested that a Blu2 / Dave might sound better than other DACs. (There view again is that any competent pro DAC is perfectly good for the job and indeed they use them all day long in their recording studios etc etc). I got out of that thread as I could not stick any more of their condescending attitude.
  3. marcmccalmont
    You'll have to get Rob Watts to chime in for a correct answer but I made a pair of coax with small ferrites on the signal wire. Installed between Blu2 and Dave, Dave would not lock on "no Data" and these ferrites filter above a GHz, the same cable works fine into Blu2. Large ferrites over the outer shield work fine and the large ferrites improve SQ I think the noise issue is ground noise not signal noise
  4. rayl
    There is also the caution of reviewing the specs on the ferrites carefully as you want them to attenuate the frequencies of your interference and not attenuate the frequencies of the signals you are transmitting....
  5. adyc
  6. Jawed
    "Suppose" is the problem.

    I agree that a DAC shouldn't sound different because of the USB cable (or use of ferrites or the streamer/server). Some of Rob's early designs use large numbers of optical isolators internally, apparently to deal with noise problems. Is that approach viable with DAVE?

    It doesn't matter when you use lots because the frequency range is broad and the strength of filtering increases as you add more:) The costs of lots is so low that it should be the default configuration.

    If you use a ferrite clipped around the entire cable it has no effect on the signal being transmitted, because the signal in the cable is a differential signal and ferrites filter common mode signals (which is the RF noise).

    Without filtering, that RF noise appears on the 0V reference within DAVE. Apparently, because that 0V reference is common for both digital and analogue circuits, it causes sound quality problems.

    Now playing: Movietone - Darkness Blue Glow
  7. rayl
    Maybe my memory is incorrect -- I thought ferrite chokes are modeled as inductance and hence will add reactance to the wire. But I defer to the true EE folks as I gave up on EE after 2 classes... Good point on the differential signal as my memory applies to a single wire.
    Last edited: Nov 10, 2017
  8. Deftone
    Is that the Virtex ultra scale ?
  9. marcmccalmont
    Yes Virtex Ultrascale + I hope Rob is listening to 100,000,000 taps on a prototype!
  10. Deftone
    Wow is it really that powerful? I thought the one used in blu2 was a big jump already.
  11. marcmccalmont
    No just kidding but 10,000,000 taps plus a DAC would be reasonable and on the same fpga we would not have these spdif coax issues!
  12. Deftone
    I am curious though let’s just say 1 million taps is more than enough for CD and no need to use any more, what are the other areas to improve, 50e pulse array etc ?
  13. marcmccalmont
    Personally I'd like an industry standard bandwidth increase to 40 KHz vs 20 Khz most would argue your not a bat and cannot hear it but your ear can sense a rise time equivalent to over 30 KHz RCA and Bell Labs did many experiments in the early days of audio. One experiment was to feed 30 KHz into one ear and 32 KHz into the other via headphones if you listen to one side or the other you hear nothing if you listen to both you hear the 2 KHz beat frequency. That's why a good turntable cartridge manages such good high frequencies, a Denon DL S1 is flat to 50 KHz! one reason I choose tweeters that go out to at least 35 KHz w/o breakup modes and why so many soft dome tweeters sound soft and metal dome tweeters sound harsh! So please an ADC and a DAC that digitizes and converts 18 HZ to 40 KHz please! Oh one other request since a typical symphony has 120 db of dynamic range lets shoot for more than that in recorded music!
    Just some trivia if you sit in an anechoic chamber for long enough you start to hear a noticeable hiss they say that's the air molecules bouncing off you eardrums! Our hearing is better than we give it credit for!
    Last edited: Nov 10, 2017
    DaveRedRef-III and Christer like this.
  14. rayl
    Alas, at the current oversampling rate, we would need to wait over 11 seconds from hitting play on the PC until we hear sound... So we might need the time machine component as well to skip the wait.
  15. ray-dude
    There is always a use for more processing power: multi-channel configurations, ultra precision audio room correction/equalization, digital crossovers, etc, If you have a known precision reference on the ADC side (Davina) and the DAC side (BluDAVE): once you can close the loop, exciting to think what can be done with digital processing to correct any remaining issues from the room/speakers/etc

    I'm just hoping my 50 some year old hearing doesn't give out before all this awesome sees the light of day!

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