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Discussion in 'High-end Audio Forum' started by magiccabbage, May 14, 2015.
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  1. paulchiu
    Things like the Regen has a noticeable effect with Hugo and ZX2 players but with Chord Dave and Nagra HD DAC, the effects are minimal to none.
  2. rkt31
    usb data can have jitter which is corrected by Dave. but usb data can also have some noise which may creep into the electronics. so a less noisy source can have some improvements with dave as reported by some members. so theoretically a usb reclocker is not required for dave. imho adding more active electronics around dave can have some minor negative effects so instead passively removing/blocking noise through usb cable may be a better idea with dave. imho try a single ferrite core near dave end on the usb cable and also use a audioquest jitterbug between usb port of pc and cable. contrary to what the name suggests jitterbug only removes noise from usb power passively (jitterbug does not require external power) and does not relcock data.
  3. esimms86
    Rob states emphatically that DAVE via USB has full galvanic isolation(see post #3384) so I don't see what the Intona would have to offer you in this case. That's 300 USD that you can spend on music instead.
  4. Arpiben
    I fully agree your point, but I still have a small doubt regarding the fact that, in my mind, in order to be fully efficient galvanic isolation has to be applied at both ends; i.e. Player/DAP output and DAC input.
    Otherwise the isolation at DAC input will not remove the jitter/noises/RFI eventual modulations generated at DAP Output.
    For sure DAVE has got other 'tricks/solutions' to remove those further ahead in data audio chain for removing them..
    If Rob or somebody else can elaborate/detail more this point I will aprreciate.
  5. x RELIC x Contributor

    This post, and subsequent posts on the same page, by Rob might help:


    Also, there's this very helpful summary of Rob's posts by romaz:


    Mython and Arpiben like this.
  6. Rob Watts
    This is a good question, and something I have been puzzling over myself - thrown into focus when I heard that my lap-top sounds a bit smoother on battery operation than with the PSU connected. By using batteries you are effectively double isolating, as it is no longer connected via the mains supply and the lap top ground is completely floating.
    Now we have two effects going on when you galvanically isolate; reduction in RF noise via ground loops, and the elimination of audio currents (signal related but distorted principally due to the massive change as all bit flip from 1 to zero as you cross through analogue zero).
    Now the galvanic isolation is not 100% as there is a residual 2pF coupling capacitance. At 1 kHz this represents 79 M ohms - so low frequency noise will be eliminated. But at 1 GHz its a much smaller 79 ohms - so is more significant and potentially a problem.
    So is the lap top isolation because Dave is getting noise via the mains, or is it through the 2pF galvanic isolation? 
    Well it occurred to me that I can test this out using Audioquest Jitter bug - which acts as an RF filter so that you filter the ground power and signal lines. Now if I can hear no difference via the jitter bug, then that suggests that the RF noise path is via the mains. If the jitter bug means that using it reduces the effect of battery isolation then its via the galvanic isolation.
    I am in Asia at the moment, and packed a Dave and a jitter bug, so as soon as Davina PCB is finished that is my next task.
    I will report back on the results. I should emphasis that we are talking quite small differences here, it is something you can only just hear with careful AB tests - its certainly not a big issue.
    Another point is another layer of galvanic isolation like the one in Dave at the source would not eliminate the problem - only half it. The 2pF becomes 1pF.... And the extra circuitry would create a bit more noise.
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  7. Arpiben

    Gratefully Thanks.
  8. AndrewOld
    Rob, there's another possibly useful device called an Intona High Speed USB Isolator. See here: http://intona.eu/en/products
    It apparently offers galvanic isolation, and rechecks the original data.
    Intona publish lots of measurements and technical information here:
    I don't understand most of this, but I dare say you will!
    I would like to squeeze the last ounce of performance from my DAVE, which is utterly incredible I have to say, every day I listen to it I realise more how incredible it is, so I look forward to you getting to the bottom of your observations about running your laptop from batteries.
  9. analogmusic
    I think it is important to trust Rob Watts and not get particularly obsessive about these Galvanic isolation issues 
    After reading many hundred of pages I am somewhat still perplexed about how many people still don't quite understand what Hugo and Dave are really about.
    I'll only repeat what Rob has said many times below about listening fatigue being eliminated with his DACs
    Originally Posted by Rob Watts [​IMG]
    Its a brain issue, and is (mostly) down to two technical problems - one being noise floor modulation, one being timing uncertainty. With timing uncertainty, when the sampled digital data is converted back to a continuous signal, the DAC creates timing errors. These timing errors then interfere with the brains ability to actual perceive the starting and stopping of notes - and when the brain can't easily recognise something, it has to work harder to make sense of what is going on. Its a bit like one being in a party trying to understand somebody speaking with a lot of noise - your brain has to work harder to understand the voice, and its tiring. The noise floor modulation problem, means that the brain has greater difficulty separating sounds out into individual entities. What people forget, as we take hearing for granted, is that the brain is processing the data from the ears, and separating things out into individual entities, and also putting a placement tag onto that entity. Noise floor modulation makes it more difficult for the brain to separate things out into individual entities, so the brain has to work harder to make sense of the music. And when it has to work harder, you get listening fatigue.
    Now the timing issue is a unique problem with digital audio, and noise floor modulation is about ten times a larger problem than with amplifiers, so you can see why listening fatigue is a particular problem with digital.
  10. Beolab
    @Rob Watts

    Just a curios question:

    Is there any scheduled plans to design a dedicated streamer for the DAVE in the future, who can take benefit of your groundbreaking technology?
  11. esimms86

    While I'm certain that Rob could work his usual musical magic in deserving a server to mate with DAVE, he's a man with a lot on his plate and I don't see where that's a priority of his right now.

    In the meantime, the microRendu with the Uptone Audio JS-2 power supply works wonders when connected to DAVE and likely any other DAC for that matter. The midbass(particularly separating the sound of one percussion instrument from another) and midrange(particularly as it applies to reproducing the sound of a piano or the human voice) are especially outstanding with the microRendu when connected to DAVE and even lesser DACS(e.g., the Auralc Vega and Geek Pulse Infinty SE in my home). Instrument decay with the microRendu brings the aforementioned DACS even closer to DAVE territory. I'm personally over the moon with the microRendu and DAVE. If you can afford it, a higher end power supply relative to the iFi 9v PS is well worth the money.
    shuttlepod likes this.
  12. stvc

    Any reason you choose JS-2 PS over of the snore signature PS?
  13. iDesign

    Interesting. Looking forward to your thoughts on the merits of the JitterBug. 
  14. maxh22
    Out of curiosity, what differences have you heard when comparing the Vega and Dave? I'm very familar with the Vega sound so your input on how it compares would mean a lot.
  15. esimms86

    I already had one powering other devices(the Auralic Aries, and the Geek Pulse Infinity SE). I also had an idle iFi 9v power supply sitting around.

    My understanding, however, is that the Sonore Signature PS won't put you to sleep LOL!
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