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Old 26th July 2014, 11:06 PM   #161
soekris is online now soekris  Denmark
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Quote:
Originally Posted by livingstone View Post
soekris,

Very interesting, subscribed.
Didn't find any information on listening tests in the thread. What would you say about the sound quality if to compare with top delta-sigma? Is there any fundamental audible differences?
Thanks.
Not far enough to do listening tests. The goal is to do the absolute best sounding DAC on earth, but then, people have different preferences, or have access to tech from other planets....
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Old 27th July 2014, 12:31 AM   #162
soekris is online now soekris  Denmark
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About the FFT plots:

I did some googling and at some point stumbled over a company called Metrum Acoustic making a series of Audio DACs, apparently using an obscure industrial DAC chip, the DAC8580.

They have great reviews, one of the with FFT plots:

http://www.metrum-acoustics.nl/octavehificritic.pdf

Looks like my -1 db plot, except my DAC have about 20 db less harmonics....

Also, a review of the MSB Platinum with FFT plots, again like mine, just a little lower, probably like my 0.01% version will look like:

MSB Technology Platinum Data CD IV transport & Diamond DAC IV & D/A converter Measurements | Stereophile.com

Seems like those kind of harmonics by them self is not a problem :-)
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Old 27th July 2014, 05:03 AM   #163
Calvin is offline Calvin  Germany
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Hi,

Quote:
We need a ABX blind test
Sorry, but how do You think could it be possible to gain ain insight about the sonic quality of R2R Core vs. SigmaDelta Core, if almost everything that could possibly be different is different?
The whole digital Frontend differs, the supplies differ, the PCB Layout differs, the output stage differs, etc. etc. ...... heck, even the taste of the Listener differs.
If You change a thousand parameters at the same how could You possibly tell that parameter 269 is the one that decides?
Its my impression that Súren has put in much sensible thinking and has provided his DAC with good genes.
That alone will make it the best DAC for some people

@Súren
You said You kill capapacitive glitches theat occur inside the R2R network with a single 470p cap at the output, as the single switches are not compensated individually.
That hides the inherent problem of very fast switching of (stray) capacitive loads, but doesn't cure it.
Could You measure the bandidth limit of the DAC yet?
Is 384kHz clock possible at full bandwidth?
Hows about higher clock rates?

jauu
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Old 27th July 2014, 06:51 AM   #164
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A listening test is the only way to decide if you like it, no matter what techniques are used and how good specs are.
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Old 27th July 2014, 08:30 AM   #165
EUVL is offline EUVL  Europe
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For those who might wish to understand some basics and the challenges of a discrete R2R DAC, here are a couple of useful links :

Discrete DAC
Discrete R2R DAC
DIY Discrete R-2R Ladder DAC: Serial Data Demultiplexing

The fundamentals are still more or less the same.
It is still using 74xx595 to switch, and uses the power supply of the 595 as output voltage reference.
So all the challenges remain.

http://liu.diva-portal.org/smash/get...FULLTEXT01.pdf
NerdKits - R-2R ladder using random crap resistors (Basic Electronics)

In the end the measurement capability limits the performance, even if you are prepared to go to all extremes.


Patrick
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Old 27th July 2014, 08:42 AM   #166
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Originally Posted by soekris View Post
With a typical PSRR of 125 db I didn't worry much about 100/120 hz ripple, only worried about higher frequency noise on the power rails....
How good your power circuit's are, will tell you the freq. spectrum in the 200Hz to 10Hz region...

Hp
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Old 27th July 2014, 08:47 AM   #167
Calvin is offline Calvin  Germany
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Hi,

so Yes the listening will be a personal opinion.
Some will vote in favour of one device, some will favour a different device.
You could as well make a ABX on the DAC vers. some analog vinyl stuff or any other source. The outcome of the ABX would be similar.
In which way does Your ABX tell anything about which technology of the DAC core maybe superior -in what respect/parameter anyway?
All this is known even before a single note is played through the DAC and listened to.
In #56 I reported that our own tests -which very much more looked at the differences of the DAC cores than a ill defined ABX test- resulted in a small majority of listeners preferring the Sigma Delta Core, but admittedly not truely distinguishable but on the most capable stereo setups.

SŲren has done a marvellous job so far and I'm sure that in the end the DAC will be good enough that any decision for better, more musical or whatever is solely a matter of personal taste or preference.

SŲren, I assume You measured the waveforms without the 470pF Lowpass and can tell that no glitches or even faulty switching bits occur (i.e. that glitches may occasionally and by accident trigger the wrong Bits)?

jauu
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Old 27th July 2014, 11:21 AM   #168
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Calvin,

ABX testing can cause a sensory null effect, where our perception tells us two devices are the same during the ABX, when they are different when listened to alone, this is due to pre-attentive processing.

See this paper for some testing in that direction ----- http://www.partsconnexion.com/t/clar...ch_Summary.pdf

See you
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Old 27th July 2014, 12:39 PM   #169
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Quote:
Originally Posted by Kastor L View Post
Calvin,

ABX testing can cause a sensory null effect, where our perception tells us two devices are the same during the ABX, when they are different when listened to alone, this is due to pre-attentive processing.

See this paper for some testing in that direction ----- http://www.partsconnexion.com/t/clar...ch_Summary.pdf

See you
Remember all blind listening is not = ABX.
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Old 27th July 2014, 12:44 PM   #170
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Quote:
Originally Posted by soekris View Post
About the FFT plots:
Sign magnitude only addresses the major carry. Find one of the carry glitches that are still there and do your -60dB tone with that point as the center. Or surprise your self with the noise floor of a mutitone FFT.
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