Douk Audio U2 Pro DDC - Poorman DDC for an affordable & clean digital signal
Dec 14, 2022 at 11:50 PM Post #406 of 589
Thanks. Very informative.
I am just curious what better clocks could do to SPDIF, and I am fine with the antipated disappointment of no audible difference.
Don't give up, let it burn. :)

While it is true that PLL in S/PDIF receivers is following source clock filtering high frequency changes, I don't agree to the conclusion. PLL filtration is weak in the acoustic range, quality of the source clock is extremely important in the low frequency range, where PLL just follow source clock with minimal filtering effect. It is most noticed in the bass and middle range, but harmonics of the basic tones spread to the high range, so sound becomes more coherent in the entire spectrum.
 
Dec 15, 2022 at 2:18 AM Post #407 of 589
Don't give up, let it burn. :)

While it is true that PLL in S/PDIF receivers is following source clock filtering high frequency changes, I don't agree to the conclusion. PLL filtration is weak in the acoustic range, quality of the source clock is extremely important in the low frequency range, where PLL just follow source clock with minimal filtering effect. It is most noticed in the bass and middle range, but harmonics of the basic tones spread to the high range, so sound becomes more coherent in the entire spectrum.
:dt880smile: Actually, I was waiting for you to do the clock upgrade, so I can decide if it is worth it. Now you are asking me to do it. :beerchug:
I haven't solder anything in the last two decades, but I will try to solder in the NZ2520SDA. Do you think I am too optimistic?
 
Dec 15, 2022 at 5:20 AM Post #408 of 589
:dt880smile: Actually, I was waiting for you to do the clock upgrade, so I can decide if it is worth it. Now you are asking me to do it. :beerchug:
I haven't solder anything in the last two decades, but I will try to solder in the NZ2520SDA. Do you think I am too optimistic?
Not my fault, didn't want waste Crysteks on the unit that is only partially working. I changed one oscilator (standard type) just to see whether it would fix a problem, but no changes, I cant play DSD or 176k PCM, while I can play 192k and other sampling rates.

What I remember there are no pads on the PCB for NDK size, so you would have to extend contact points with a piece of wire to get job done, not a nice job. Better get Crystek from Mouser or Digikey.
 
Dec 15, 2022 at 5:37 AM Post #409 of 589
Dec 15, 2022 at 8:07 AM Post #410 of 589
I ordered a Douk Audio U2 PRO from Amazon and it arrived yesterday. Set up was easy. I've got it set up as follows: PC > USB > U2 Pro > Coax > DAC > Pre-Amp > Amp > Speakers. I haven't spent enough time with it to determine if it is better than the USB implementation on my Gungnir MB (Gen 5, not Unison). I don't think it is as good as listening to the same files ripped to a CD and played using my SACD player as transport via Coax into the DAC. I'll need to make sure volume is leveled before I can make that determination. It sounds good, though.
 
Dec 15, 2022 at 8:22 AM Post #411 of 589
While it is true that PLL in S/PDIF receivers is following source clock filtering high frequency changes, I don't agree to the conclusion. PLL filtration is weak in the acoustic range, quality of the source clock is extremely important in the low frequency range, where PLL just follow source clock with minimal filtering effect. It is most noticed in the bass and middle range, but harmonics of the basic tones spread to the high range, so sound becomes more coherent in the entire spectrum.
Wheres your data to back all those words up?

There are plenty of J-test data with DACs that have PLL that effectively strip jitter out of SPDIF; even with TOSLINK in that usually has very high jitter, far exceeding even the worst coaxial SPDIF.

How about the humble Ares:
1671110266978.png


Its nice when one measurement destroys all kinds of speculation.

With any decent DAC investing money in very high performing clocks for SPDIF DDC is a poor allocation of limited audio budgets.

Much better to put the $ towards better headphones.
 
Dec 15, 2022 at 8:26 AM Post #412 of 589
I ordered a Douk Audio U2 PRO from Amazon and it arrived yesterday. Set up was easy. I've got it set up as follows: PC > USB > U2 Pro > Coax > DAC > Pre-Amp > Amp > Speakers. I haven't spent enough time with it to determine if it is better than the USB implementation on my Gungnir MB (Gen 5, not Unison). I don't think it is as good as listening to the same files ripped to a CD and played using my SACD player as transport via Coax into the DAC. I'll need to make sure volume is leveled before I can make that determination. It sounds good, though.

The issue may be the USB quality out of the PC. A disc spinner is electrically quiet in comparison. . Try TOSLINK from the DDC to isolate the PC hash. If TOSLINK is lacking look at the Intona USB filter for coaxial. Or get a better DAC :)
 
Dec 15, 2022 at 1:30 PM Post #413 of 589
The issue may be the USB quality out of the PC. A disc spinner is electrically quiet in comparison. . Try TOSLINK from the DDC to isolate the PC hash. If TOSLINK is lacking look at the Intona USB filter for coaxial. Or get a better DAC :)
Thanks for the tips! DAC is fine - Gungnir MB, but USB is not the best part of the DAC.
 
Dec 15, 2022 at 2:56 PM Post #414 of 589
Wheres your data to back all those words up?

There are plenty of J-test data with DACs that have PLL that effectively strip jitter out of SPDIF; even with TOSLINK in that usually has very high jitter, far exceeding even the worst coaxial SPDIF.

How about the humble Ares:


Its nice when one measurement destroys all kinds of speculation.

With any decent DAC investing money in very high performing clocks for SPDIF DDC is a poor allocation of limited audio budgets.

Much better to put the $ towards better headphones.
.LOL. Your ignorance bring you wings! :)

First at all, did you notice that I was talking about jitter in a low frequency acoustic range and your graph contains very narrow window around 12kHz? There is also a different measuring method, purpose and equipment, no matter for this discussion.

A point I am going to make is not about your arrogance, you were so close, so close to become a successful bully, but you will find yourself, that it was complete rubbish. That's my point.

There is a high performance Crystek CCHD-575 oscilator with specs 82fs (fem-to-second) phase noise jitter in the frequency range 12kHz-80MHz. Note that it is a total (RMS) value of jitter, but your graph shows distribution of jitter vs. frequency. So take a look at this:

Crystek_CCHD-575jpg.jpg

Do it look completely different? Not, it is measuring even better, below -160dB at 10kHz, roughly the same, but what happen at lower frequencies? A complete disaster! This is the area I am interested, as -160dB is extraordinary low, undetectable by our ears. The best oscilators show figure at 1Hz, this one below 10Hz is unspecified.

And now a little secret. This oscilator is built with use a specialized PLL to achieve fem-to-second specs. Why PLL is not able to filter phase noise in the range 10Hz? Answer yourself, I just supplied an evidence
 
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Dec 16, 2022 at 3:38 AM Post #415 of 589
I really don't know how one digital to digital converter can be louder than another. Honestly, no way. I think something has changed by mistake in your player.

EDIT: I see post from @Nada , i agree, but it is unlikely that these guys have a knowledge and invested in development system from XMOS. They will rather buy pre-programmed chips from bigger guys.

Give both more time to burn leaving it powered in the USB port and report back after a week. TCXO takes more time to achieve optimum performance. But in a Chineese product TCXO can be fake, be prepared for that.
The Aliexpress product is manufactured by Breeze Audio. There are some review of breeze audio products (not the same one). For example,
https://www.audiosciencereview.com/...ments-of-breeze-audio-es9018-dac-hp-amp.8818/

Although not the same product, I would think they are built with similar quality.
I am thinking maybe the harmonic distortions make me think it is louder. Is it possible for DDC to create harmonic distortions?

From my listening experience, I can hear more resonance sound in the breeze audio product. It is like pedal is pressed when playing piano.
 
Dec 16, 2022 at 6:15 AM Post #416 of 589
I am thinking maybe the harmonic distortions make me think it is louder. Is it possible for DDC to create harmonic distortions?
Of course, not, unless data is processed, but it was just discussed that it is possible but unlikely.

It could be a case that your analogue stage works on the border distorting data. The link you provided bring suggestion for such case. It is what happens: Jitter in the D/A converter means that digital samples are converted to the analog in the wrong time. In result analogue values after reconstruction can excess a maximum value that corresponds to the digital maximum it would be generated without jitter. Then in a combination with distortion level of the amp, it would be heard. I see, Amir made (again) an extraordinary claim without verification. He should know how to deal with this problem. It is sufficient to lower volume of the digital sample by 3 dB and retest.

There is a similar mechanism generating extraordinary values during oversampling, called intersample overs. And dealing with this issue is the same. Reduce volume before oversampling. You can try yourself. Reduce volume in your player and retest both converters using the same (reduced) volume.
 
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Dec 16, 2022 at 4:39 PM Post #417 of 589
Of course, not, unless data is processed, but it was just discussed that it is possible but unlikely.

It could be a case that your analogue stage works on the border distorting data. The link you provided bring suggestion for such case. It is what happens: Jitter in the D/A converter means that digital samples are converted to the analog in the wrong time. In result analogue values after reconstruction can excess a maximum value that corresponds to the digital maximum it would be generated without jitter. Then in a combination with distortion level of the amp, it would be heard. I see, Amir made (again) an extraordinary claim without verification. He should know how to deal with this problem. It is sufficient to lower volume of the digital sample by 3 dB and retest.

There is a similar mechanism generating extraordinary values during oversampling, called intersample overs. And dealing with this issue is the same. Reduce volume before oversampling. You can try yourself. Reduce volume in your player and retest both converters using the same (reduced) volume.
Thanks. So it is not directly, but jitter out of DDC could make it harder for DAC to work.
I am using a R2R DAC with over sampling. Correct me if I am wrong, I think over sampling is more sensitive to jitters.

I am not sure jitter only affects the maximum value. At least for R2R, I think it can affect the shape of the wave anywhere.

PS - I did a little search and found Breeze audio seems to be affiliated with Weiliang audio.
Here is another review (not by Amir) of a DAC
https://www.audiosciencereview.com/...ments-of-weiliang-audio-2019-dc300-dac.10094/
 
Dec 19, 2022 at 10:14 AM Post #419 of 589
but jitter out of DDC could make it harder for DAC to work.
If you are using SPDIF and a well-designed DAC the jitter out of the DDC is irrelevant. The DAC will buffer and reclock. You would be well advised to check the credibility of other posters. Just cause someone can use techinal terms doesnt mean they know what they mean.
If you use I2S and the DAC runs on the DDC clock then jitter might matter but it's very hard to hear in music.
I am using a R2R DAC with over sampling. Correct me if I am wrong, I think over sampling is more sensitive to jitters.
R2R is relatively immune to jitter DS. Oversampling decreases jitter. The period reduces.
is this worth buying for an ARES2?
Depends on your USB quality and if you like oversampling. Some USB sources sound really bad. Buy an Intona and the USB usually sounds excellent. USB allows x32 upsampling if you are into that. SPDIF maxes out at x4. But if you use TOSLINK you get complete isolation. The Ares is imune to the really bad jitter in TOSLINK.
 
Dec 19, 2022 at 10:23 AM Post #420 of 589
.LOL. Your ignorance bring you wings! :)
...............
A point I am going to make is not about your arrogance, you were so close, so close to become a successful bully, but you will find yourself, that it was complete rubbish. That's my point.
This post needs to be called out.

You have achieved the heights of hypocrisy. Anyone looking at this can see my post discussed just the technical matters and did not target you. Your response is too arrogantly denigrate on a personal level.

You are an arrogant bully.

You are also technically ignorant and cant follow a basic logical thread.

But what's worse is you encourage members to waste their money.

The odd thing is you do this in writing for everyone to see your true worth. Good luck.
 

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