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A comparison between two DACs, one R-2R, the other ES 9038-based.

This is an item from the FWIW Department, I guess.

Recently I set up an A/B comparison between a Denafrips Pontus and an OPPO Sonica…. Both DACs fed from a Nuprime CDT-8, via the XLR inputs on the same preamp, and everything else constant through the two signal paths to the speakers.

The result when I repeatedly toggled back and forth from the preamp’s input one [Denafrips] to its input two [OPPO]?---- To my surprise [and disappointment], the sounds from the two DACs were utterly indistinguishable, across all kinds of music, after repeated trials … impossible to tell apart… impossible.

The moral of the story? I don’t really know, but it does suggest to me that those who say that DACs of comparable quality cannot be told apart just might have a point.

I bought both the Pontus and the Sonica because I thought that it would be nice to have on hand DACs of “different flavours,” one based on an R-2R ladder, the other based on a delta-sigma chip. 

I did want the expected difference to be real… just for the fun of it… else why spend the extra money? So, my “confirmation bias” was, if anything, stacked in favour of there being a detectable difference.  

However, the results of a reasonably well controlled comparison [sadly?] did not bear out that expectation. Differently based DACs, 2-R2 vs delta-sigma, may not offer such different flavours as many suggest. Is that claim all much ado about nothing?

Thoughts from members of the Forum?

 

 

 


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celander's avatar
celander
1,503 posts
 
The NuPrime CDT-8 Pro transport has a high jitter output (190 psec), which was far higher than my 1996 CAL Delta transport (<50 psec). The CDT-8 transport sounded unremarkable—clearly not superior to the Delta transport—when fed to my Theta DSPro Basic 3A R2R 20-bit, 8x oversampling DAC. 

I then aquired a Jay’s Audio CDT2 MK2 transport. Superb top-loader with ultra low jitter. Result when connected to the Theta DAC? Best Redbook CD playback ever from my system. Micro and macro dynamics, imaging, resolution and soundstage extended well beyond the offerings of the other two digital transports when combined with the same DAC. 

My take-home message is that the jitter-encoded signal from the transport likely contributes significantly to how well one can distinguish playback differences in the DAC, as well as whether the full potential of the DAC can be realized.

In my case, the transport made a huge difference. I suspect the same effect is taking place with your system, where a jittery transport over-rides any benefit afforded by the downstream DACs. 

I have heard a lot of good things about the Denafrips Pontus. I don’t know if it has the reclocking hardware of the more expensive Venus or Terminator. 
celander's avatar
celander
1,503 posts
 
Folks sell digital data stream reclockers to reduce or remove jitter. Try one for the digital stream output from your NuPrime CDT-8 Pro transport. That might help clarify how well the two DACs perform when compared.

Try shooting a pm to Steve Nugent of Emperical Audio. His member name here is audioengr. 

https://www.empiricalaudio.com
jond's avatar
jond
5,916 posts
 
zimmerma regarding having the volumes match its not just about having the volume know in the same setting. Dacs can have different outputs one Dac say an 2v output another a 3v in that case the 3v output will sound louder at the same volume setting. You really need a db meter to verify the loudness match.

Also I personally would suggest, if you can, changing up your methodology. What is often more helpful for me is putting a component in my system and listening to it at length weeks or even months. Then switching components listening some more at length and finally going back again. More subtle differences often become more apparent over time. As always just my opinion YMMV.
zimmerma's avatar
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zimmerma OP
102 posts
 
To celander:
  • Thank you for the datum on the Supreme CDT-8 jitter. I'll look into this aspect of my signal chain. 
  • Possibly changing transports or adding re-clocking would be in order. 

To jond:
  • Both DACs in the comparison have the same output voltage, 4v for the XLR outputs, 2v for the RCA. I controlled for that.
  • As for your interesting version of the earlier poster's "leisurely listening" approach, I tried to address that above, by noting that human "auditory memory" is probably not retentive enough to enable a very meaningful A/B comparison of components in a signal path. In my earlier response I referred to my own weak auditory memory, but is was just a weak attempt at false modesty; I really meant all human beings. Psychodynamic studies show that we just cannot remember enough about a sound series we heard as little as a few minutes ago to make accurate comparisons with one we are hearing now. [I'll dig out a study if I can. It's been awhile.]
Again, a general note a thanks to responders. I am finding these comments on my OP very useful.
zimmerma's avatar
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zimmerma OP
102 posts
 
A question for celander:
Where can I find the jitter rate of 190 psec that you quoted for the Nuprime CDT-8?
Thanks....
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