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Old 13th February 2004, 02:26 AM   #11
ojg is offline ojg
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Since there have been some interest in how I did the jitter measurements I updated my webpage. You can also download the wav-file I made for the test.

I calculated the numerical results from the plots and:
SAA7220-TDA1541-NE5532: ~480ps
DF1704-PCM1704-OPA627: ~183ps
AD1896-DF1704-PCM1704-OPA627: ~58ps

Thanks again for your comments!
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Old 14th February 2004, 06:50 PM   #12
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Quote:
Originally posted by ojg
Since there have been some interest in how I did the jitter measurements I updated my webpage. You can also download the wav-file I made for the test.

I calculated the numerical results from the plots and:
SAA7220-TDA1541-NE5532: ~480ps
DF1704-PCM1704-OPA627: ~183ps
AD1896-DF1704-PCM1704-OPA627: ~58ps

Thanks again for your comments!
Hi,

Most interesting web page and measurements

With the 1896 the masterclock is important. Also consider jitter ripple through by the data

You may look at

http://members.chello.nl/~m.heijlige...tml/dactop.htm

for reclocking and low jitter, typically 8ps (measured at DAC clock)

best regards
-
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Old 14th February 2004, 11:40 PM   #13
ojg is offline ojg
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Quote:
Originally posted by Guido Tent
Also consider jitter ripple through by the data
I am not quite sure what you mean by this, could you please explain?

I have visited your webpage in the past and I am most impressed by your PLL-VCXO design. I think this is better than an ASRC, and I will probably put something similar in my next design. I have headers on my DAC-board so that I can easily hook into the signal-path at different places if need be.
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Old 15th February 2004, 05:54 PM   #14
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Quote:
Originally posted by ojg


I am not quite sure what you mean by this, could you please explain?

I have visited your webpage in the past and I am most impressed by your PLL-VCXO design. I think this is better than an ASRC, and I will probably put something similar in my next design. I have headers on my DAC-board so that I can easily hook into the signal-path at different places if need be.
Hi

Thanks for feedback, especially on the PLL. I think the AD1896 is the first decent ASRC, the other ones hurt at least my ears, have to try the 1896.

Data jitter affects on-chip clock hence produces distortion at D to A conversion (because of on-chip crosstalk).

We did the experiments, group of 4 people, ABX testing, data input of PCM63 reclocked or not: 80% score.......

Ciao
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Old 15th February 2004, 08:30 PM   #15
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Quote:
Originally posted by Guido Tent


Hi

Thanks for feedback, especially on the PLL. I think the AD1896 is the first decent ASRC, the other ones hurt at least my ears, have to try the 1896.

Data jitter affects on-chip clock hence produces distortion at D to A conversion (because of on-chip crosstalk).

We did the experiments, group of 4 people, ABX testing, data input of PCM63 reclocked or not: 80% score.......

Ciao
G'day Guido,

TI have new one which looks even better than 1896.
THD=-140dB. Pretty impressive performance. No info
WRT jitter attenuation Vs freq though.

Cheers,
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Old 18th February 2004, 01:51 AM   #16
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OK folks, another update to the project webpage.

I have access to an Audio Precision analyzer through work, so I brought my DAC in to take some more measurements. My PCM1704 DAC got -100dB THD+N while the TDA1541 got a still decent -93dB THD+N.

What is interesting though is how much the numbers changed with measurement bandwidth...
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Old 18th February 2004, 03:23 AM   #17
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Quote:
Originally posted by ojg
OK folks, another update to the project webpage.

I have access to an Audio Precision analyzer through work, so I brought my DAC in to take some more measurements. My PCM1704 DAC got -100dB THD+N while the TDA1541 got a still decent -93dB THD+N.

What is interesting though is how much the numbers changed with measurement bandwidth...
It might be worth trying 1crown (s1) or 2 crown (s2)
versions of TDA1541A. These have guaranteed THD
figures.

Cheers,

Terry
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Old 18th February 2004, 07:07 PM   #18
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OK we have all got caught up with numbers here. How does the thing sound!!
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Old 18th February 2004, 08:04 PM   #19
ojg is offline ojg
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Quote:
Originally posted by 5th element
OK we have all got caught up with numbers here. How does the thing sound!!
I have been waiting for someone's bubble to burst and finally ask this question!

The short answer is, they sound the same! Now that is obviously not a satisfying answer so here is the long one.

I do believe in double-blind listening tests. I also believe that some people have trained their mind to listen for and discern subtle differences in sound despite less-than-ideal conditions. I do not have the equipment for ABX testing, and I don't trust my brain to be objective, especially since one of the subjects is one that I have invested so much time, effort and money (~$500) into.

But what I did hear is this: On "Great Gig in the Sky" from the CD-layer of the latest reissue of "Dark Side..." there was one point where my DAC produced a shrieking sound that made me switch back-and-forth between the Rotel, and I believe it was less pronounced on the Rotel. You all know how bad the mastering of that CD-layer is, but it was an interesting observation nonetheless. Maybe I am too afraid of being biased toward my own DAC that I am overcompensating and finding faults that aren't really there? Lots of psychology involved here unfortunately

This DAC is still a work in progress, and I started this project not because I thought I could make something that was "night and day" when compared with the Rotel, but because I wanted to prove to myself that I could build a DAC according to engineering principles that I feel are the most important, and still measure as well as the high-end commercial products out there.
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Old 24th February 2004, 12:09 AM   #20
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Hello ojg,

Could you post a schematic?


Thanks
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