CHORD ELECTRONICS DAVE
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romaz

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I think "source immunity" with the DAVE has to be looked at in relative and not absolute terms.  In the field of medicine, we define immunity as a "resistance to" meaning that a human host's immune system will have limits and that those limits can be overcome.  The DAVE is immune to source jitter but only up to 2µs as Rob has stated but since no source that any of us will likely ever encounter will have more jitter than this, then from a practical perspective, it would be feasible to say that the DAVE is truly impervious to source jitter.  Those of you who have an Oppo BDP-103 or BDP-105 and have tried to stream Tidal internally through the Oppo's own DAC know how horrible this sounds due to jitter.  Then try running it through the DAVE and hear how magically it is transformed.  It's truly a night and day difference and has thoroughly convinced me of Rob's claim about being immune to source jitter. For those wondering what jitter sounds like, here are some extreme examples (up to 16µs) that even the DAVE can do nothing about but again, this is jitter you will likely never encounter from even the worst piece of equipment:
 
http://www.sereneaudio.com/blog/what-does-jitter-sound-like
 
As for source RF, I don't think Rob has been inaccurate to say that the DAVE is immune to RF provided that people understand that this immunity has limits as well.  My own experience has shown me that galvanic isolation has allowed even the noisiest sources to sound very good but a pristine source like the microRendu has shown me that even small amounts of RF can make a difference.
 
What I have been observing lately is that the people that are now crying foul that the DAVE isn't completely immune to the source are non-DAVE owners.  Once you become a DAVE-owner, such concerns become less relevant and even trivial because all that a DAVE owner knows is that everything he or she listens to sounds terrific and while some sources can sound better, no source ever sounds horrible.  
 
 
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romaz

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  At first we were told that DAVE was immune to any interferences and now   during the past couple of months there have been reports of clear  improvements with different add ons and plugin´s and connections which we were initiallly  told  would not make any audible dfferences at all, to the SQ of DAVE.
And now it seems even Rob Watts himself recommends using a 40 bucks or so,add on, Audioquest Jitterbug with DAVE!  if you run your laptop plugged in.
I believe the audiophile journey is made up of discoveries and even the brightest and most experienced among us are always still discovering and learning new things.  The day that Rob believes he has learned everything possible is the day that we should all start looking elsewhere for our next DAC.
 
 
  Back home in my stereo Hugo  has given me more problems than pleasure and doesn´t even work at all, that way any longer.
All it produces when connected to my stereo amp now is loud, very loud hum!
And more often than not it also sounded thin and sibilant, before shutting down completely.
This is unfortunate.  Hopefully, yours is still under warranty.
 
 
  I am currently using a properly galvanically isolated Benchmark DAC 2HGC in my system and it is good enough SQ wise to let me hear that  problems I have with SQ and certain  recordings are faults of the particular recordings,not the DAC.
And it sounds the same round the clock with no  differences with my macbook pro connected to the wall or running on battery.
It seems immune indeed.
It sounds like you've already found a great DAC.  Congratulations.
 
  I was very  impressed by DAVE via headphones . But not even now with the Pound down would I buy one at such stratospheric pricing and still in need it seems of tweaks and  add ons.
Though I have to admit that I might be tempted to buy a Chord DAC  if they bring on a properly isolated and shielded! portable DAVE SQ  DAC at a price point around Mojo´s.
And of course! A portable DAC that also works equally well connected to a stereo system via speakers.
If you can find a better solution, you should buy it.
 
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Articnoise

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  Leaving tomorrow!
 
But I will be getting hold of a microRendu to try - I am intrigued, particularly as the observation is that it is smoother, which is indicative of lower RF noise. Its a puzzle as battery supply with no earth connection ought to be the lowest way of transmitting RF noise into Dave. But weird things happen with RF, particularly at GHz frequencies. And it still may be nothing to do with Dave, but a symptom of other pick-up in the rest of the system. As I mentioned, YMWV!
 
Rob
 
 
   

The battery only isolate from the noise coming from the mains and a laptop is a computer which generate a ****load of its own noise from graphic cards, switching PSU, motherboard, software apps etc. Also there are more ways for the RF to sneak in than thru the mains, as most are airborne. 
 
 
  Airborne RF is not a problem at all for Dave - that's why it is in a solid block of machined aluminium. No RF can get in or out - except via the mains supply and I/O's. The mains supply is extremely well RF filtered, and all IO's are carefully treated for RF.
 
Note that modern homes are a RF hot spot with all the audio turned off, so its essential for good sound quality that treatments are carefully applied everywhere. Note I said carefully - RF treatment on analogue is very different to digital treatments.
 
Rob
 

Airborne RF is maybe not a problem for Dave, but sure is for a laptop or PC!

 
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rgs9200m

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This thread seems to be turning into an all-things-Chord discussion. Given that, I will say that my Hugo and Hugo TT have worked just fine and sound great and don't seem to need any signal processing add-ons like USB isolators. There is no hum, noise, dropouts or any sort of distortion (all with using just USB input). My TT sounds wonderful and I recommend it to everyone I can. I use a Windows 10 desktop with Jriver, some solid state drives, and Tidal for sources. This has been the case during 2 years of use so far and everything is going strong and I hear no reason to upgrade or improve things.
 
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shuttlepod

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What I have been observing lately is that the people that are now crying foul that the DAVE isn't completely immune to the source are non-DAVE owners.  Once you become a DAVE-owner, such concerns become less relevant and even trivial because all that a DAVE owner knows is that everything he or she listens to sounds terrific and while some sources can sound better, no source ever sounds horrible.  
 
 
Yes. Or, in my experience, no source ever sounds worse than excellent, relative to other dacs.
 
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Jawed

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My TT sounds fabulous driving my HD 800 S headphones off an ordinary high-end PC that I built for myself, using the USB cable that came in the box.

A factor in purchasing the TT was "relative immunity" to the crap that comes with using USB. I don't have a personal scale for this immunity as my previous DAC used a 50MHz bandwidth AT&T optical connection to the CD transport (not TOSLINK), so erm, digital interconnect-bourne RF wasn't in the picture there.

If there's a level of RF immunity above that seen in DAVE's architecture, then in my view that's a problem that should be solved in future DACs. There is no reason, in my view, why DACs can't do this properly. That's the beginning and end of my question: why can't a DAC do this?

I could have waited to buy DAVE last autumn instead of the TT. I chose instead to get "mostly up-to-date" with the best of computer audio, dipping a toe in the water with the TT, and a significant aspect of my purchase is about not messing about with all these stupid things that people obsess over and put between their music files and the DAC.

I post in this thread as a technophile, and a large attraction there is having a conversation with arguably the greatest designer of digital audio playback equipment.
 
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Ampus

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There is no perfect DAC; however, I understand other posters' frustration. It's as if you think that you found a perfect girlfriend to just realize later that she is a guy :). Well, maybe not that extreme.

It is also like having your doctor telling you that your hernia surgery would go perfectly and waking up finding one of your testicles is missing. Well, perhaps it is also not that extreme and no, none of these scenarios has ever happened to me.

Perhaps we should stop hunting for a perfect DAC and just enjoy the music instead. DAVE, while not perfect, is undoubtedly is one of the best DAC's out there.
 
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romaz

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My TT sounds fabulous driving my HD 800 S headphones off an ordinary high-end PC that I built for myself, using the USB cable that came in the box.

A factor in purchasing the TT was "relative immunity" to the crap that comes with using USB. I don't have a personal scale for this immunity as my previous DAC used a 50MHz bandwidth AT&T optical connection to the CD transport (not TOSLINK), so erm, digital interconnect-bourne RF wasn't in the picture there.

If there's a level of RF immunity above that seen in DAVE's architecture, then in my view that's a problem that should be solved in future DACs. There is no reason, in my view, why DACs can't do this properly. That's the beginning and end of my question: why can't a DAC do this?

I could have waited to buy DAVE last autumn instead of the TT. I chose instead to get "mostly up-to-date" with the best of computer audio, dipping a toe in the water with the TT, and a significant aspect of my purchase is about not messing about with all these stupid things that people obsess over and put between their music files and the DAC.

I post in this thread as a technophile, and a large attraction there is having a conversation with arguably the greatest designer of digital audio playback equipment.
Valid points.  Just to be clear, just like your TT, the DAVE doesn't need any of these "stupid things" that you talk about to sound exceptional.  It is, in fact, the least fussy DAC I have ever owned.  Use the 18g mains cable that comes with it along with almost any USB cable or optical cable and paired with even the dirtiest PC, you will still probably be better off than most.  If you choose not to listen to anything else, then you're all set but most technophiles (and especially head-fiers) that I know are tinkerers and trying out new things is part of the fun.  If this wasn't the case, I would still be using the stock earbuds that came with my Sony Walkman years ago.
 
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Thanks Rob, Dave is not using ASRC, right?
Absolutely not when using USB, as the system clock is the source of all data timing - the USB is locked to the FPGA.
 
For asynchronous inputs (all of the others) the digital phase lock loop (DPLL) steps in, and together with a small buffer, re-locks and re-times the data to the FPGA clock. This is how incoming jitter is removed from an asynchronous source.
 
The benefit of my DPLL is it does not have the enormous problems of a conventional PLL as its impossible for an analogue PLL to eliminate incoming jitter, and it always suffers from low frequency jitter problems, which are highly audible. Additionally, PLL suffer from correlated jitter problems that are impossible to eliminate. That's why analogue PLL takes ages for the clocks to settle, but Dave will be perfect within a second. But to make my DPLL work as well as a local clock took a lot of work and six years to optimize the code. In fact, I call it a DPLL but it actually isn't phase locked - its frequency locked and employs a tiny buffer to remove incoming jitter. The phase locking only applies in the first second of acquiring lock; once it has acquired lock, the phase detector is switched off and everything is then controlled via a 10 second frequency measurement. The benefit of this is that its impossible for the jitter of the incoming source to affect the output of the DPLL as data is taken out from the tiny buffer via the local clock.
 
Sorry if I have confused you with my answer as it is a very complex subject and not easy to explain.
 
Rob 
 
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x RELIC x

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Absolutely not when using USB, as the system clock is the source of all data timing - the USB is locked to the FPGA.

For asynchronous inputs (all of the others) the digital phase lock loop (DPLL) steps in, and together with a small buffer, re-locks and re-times the data to the FPGA clock. This is how incoming jitter is removed from an asynchronous source.

The benefit of my DPLL is it does not have the enormous problems of a conventional PLL as its impossible for an analogue PLL to eliminate incoming jitter, and it always suffers from low frequency jitter problems, which are highly audible. Additionally, PLL suffer from correlated jitter problems that are impossible to eliminate. That's why analogue PLL takes ages for the clocks to settle, but Dave will be perfect within a second. But to make my DPLL work as well as a local clock took a lot of work and six years to optimize the code. In fact, I call it a DPLL but it actually isn't phase locked - its frequency locked and employs a tiny buffer to remove incoming jitter. The phase locking only applies in the first second of acquiring lock; once it has acquired lock, the phase detector is switched off and everything is then controlled via a 10 second frequency measurement. The benefit of this is that its impossible for the jitter of the incoming source to affect the output of the DPLL as data is taken out from the tiny buffer via the local clock.

Sorry if I have confused you with my answer as it is a very complex subject and not easy to explain.

Rob 

This is all I read...

Clock lock clock lock clock clock lock clock lock....

Just kidding! :D
 
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Originally Posted by Rob Watts /img/forum/go_quote.gif
 
...Sorry if I have confused you with my answer as it is a very complex subject and not easy to explain.
 
Not confused at all, I've done a lot of research on DACs, been reading many kinds of tech discussions, finally Dave caught my eyes, my friend is now a happy dave user, it's decent. We wanna thanks for your hard work. Personally I'm hoping some super Dave is coming out in the future. Much much more crazy taps, and scary oversampling rate, like 1*10^8FS. (Sorry, I admit i am a nuts...)
 
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I'm flying to New York City in a few days, I would like to be able to listen to DAVE.
 
Does anyone know which dealer in NYC has the Dave for audition?
 
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I'm flying to New York City in a few days, I would like to be able to listen to DAVE.

Does anyone know which dealer in NYC has the Dave for audition?

Sound By Singer. Please do call ahead for an appointment with Andrew Singer.
 
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  The digital power amp is the same except for the power supply.
 
I need to come up with a better name than digital power amp as it sounds like Class D, and the actual output is linear (non switching).
 
Power DAC, a DAC with an output stage powerful enough to drive speakers directly.
 
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