Douk Audio U2 Pro DDC - Poorman DDC for an affordable & clean digital signal

[Mr BubbaHyde]

is this worth buying for an ARES2?

I don't know if this helps you out, but I enjoyed it when I used Coaxial with my Denafrips. At its price point, it's a good starting point to see if DDCs can improve your listening. I have since moved on to a Singxer DDC, but only after I decided I heard an improvement, to me anyway, lol.

Cheers!!

 

[Ghoostknight]

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:

this graph has nothing todo with jitter, its purely phase noise and since the low frequency stuff isn near the clock frequency it also shouldnt affect jitter performance
but i get it, many report phase noise also matters but calling it jitter is wrong!

 

[sajunky]

this graph has nothing todo with jitter, its purely phase noise and since the low frequency stuff isn near the clock frequency it also shouldnt affect jitter performance
but i get it, many report phase noise also matters but calling it jitter is wrong!

From Wikipedia on jitter:

Jitter can be quantified in the same terms as all time-varying signals, e.g., root mean square (RMS), or peak-to-peak displacement. Also, like other time-varying signals, jitter can be expressed in terms of spectral density.

The last jitter representation "spectral density" is on the graph I posted. The other term used simultaneously for the same things is a "phase noise".

If you have other definition for "a pure phase noise", then please enlight us. Without sorting out this matter we cannot really deal with your claim that only phase noise near base frequency affect jitter performance. Thank you, I am sure we will hear from you soon.

 

[Ghoostknight]

The last jitter representation "spectral density" is on the graph I posted. The other term used simultaneously for the same things is a "phase noise".

If you have other definition for "a pure phase noise", then please enlight us. Without sorting out this matter we cannot really deal with your claim that only phase noise near base frequency affect jitter performance. Thank you, I am sure we will hear from you soon.

ah nevermind, i guess you are right on this: https://www.digikey.de/de/articles/converting-oscillator-phase-noise-to-time-jitter
seems like i missunderstood the whole phase noise thing

 

[sajunky]

ah nevermind, i guess you are right on this: https://www.digikey.de/de/articles/converting-oscillator-phase-noise-to-time-jitter
seems like i missunderstood the whole phase noise thing

Sure. The whole things needs explanation. Those who test DACs focus on jitter introduced by a DAC in the process of conversion, (not a clock quality). The area is displayed where the biggest interferences of a test signal occour. A narrow band help it look it cleaner as well.

If a quality of a clock is a concern, full spectrum is evaluated.

 

[utneo]

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.

R2R is relatively immune to jitter DS. Oversampling decreases jitter. The period reduces.

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.

Thank you.

I agree R2R is less sensitive to jitter than DS. But isn't that because DS has a higher frequency (period reduces) than R2R?
I think because higher frequency is more sensitive to jitter, all DS DACs need to filter. Same is true for R2R over sampling. It isn't over samping decreases jitter, the filter does.

For SPDIF, isn't it one stream with both data and clock information? Jitter would affect data quality inevitably. I am not sure how "The DAC will buffer and reclock" help in this regard.

But I think "The DAC will buffer and reclock" helps if one bypasses DDC and directly uses DAC's USB input, because asyncrounous USB only sends data, and DAC will use its internal clock. Another "BUT", this is exactly why DDC with a better clock than the DAC's internal clock can improve sound quality. We want to connect to the DDC's USB input, and let the DDC output better clocked spdif, and use the spdif as input to the DAC. This will let the DAC work better than using its internal clock.
I think your point is valid if the DAC already has very good clock, then there will be less room for DDC to improve.

Again please correct me if I am wrong.

 

[pokrog]

Another "BUT", this is exactly why DDC with a better clock than the DAC's internal clock can improve sound quality.

I think a big part of it is having the DDC power noise isolated completely from both your source and the DAC are likely one of the biggest contributing factors to why a DDC can be such a big improvement. Recently I've been eying the S.M.S.L. PO100 Pro. They advertise 72ps jitter and that's lower than a Singxer SU-6 and basically on par with a Wavedream NET. If their bold claims are true or are even remotely close to reality, it could completely displace basically all other DDCs out there and it's only $70 but my main worry is that it wont have good power isolation because it takes both its power and signal from USB but proper filtering could make it a non issue, though I have SERIOUS doubts.

 

[sajunky]

but my main worry is that it wont have good power isolation because it takes both its power and signal from USB but proper filtering could make it a non issue, though I have SERIOUS doubts.

Correct. U2Pro has no isolation, it is a poorman DDC. If you use it with external power supply, it will redirect ground loops and protect from entering a DAC. Can be used with other redirectors like iDefender.

When talking about a real DDC, all will outperform U2Pro. Audio DG DI-20 and a version with regenerative power supply don't need a recommendation (especially HE version). All these DDC's mentioned in your post use similar fem-to-second clocks, differences in specs are minimal. A difference is in marketing. A real difference is in implementation.

 

[utneo]

Correct. U2Pro has no isolation, it is a poorman DDC. If you use it with external power supply, it will redirect ground loops and protect from entering a DAC. Can be used with other redirectors like iDefender.

Would toslink help?

 

[sajunky]

Would toslink help?

Tried both. Coax gives better SQ in most cases and optical is limited to 96kHz. I use optical to feed from a TV set which is on a different power extension.

 

[utneo]

Tried both. Coax gives better SQ in most cases and optical is limited to 96kHz. I use optical to feed from a TV set which is on a different power extension.

Does coax sound better than toslink when coax plays at a higher resolution or when both play at the same resolution (say 24/96)?

 

[sajunky]

Does coax sound better than toslink when coax plays at a higher resolution or when both play at the same resolution (say 24/96)?

Even at the same sampling rate coax sounds better. At least on my system, where I take care of ground loops.

 

[utneo]

Even at the same sampling rate coax sounds better. At least on my system, where I take care of ground loops.

Interesting. Maybe different cable quality?
I slightly prefers toslink, because it has slightly cleaner background, but I doubt I can pass a blind test.

 

[sajunky]

Interesting. Maybe different cable quality?
I slightly prefers toslink, because it has slightly cleaner background, but I doubt I can pass a blind test.

Did you try iDefender before U2Pro?

 

[emilsoft]

U2Pro has me interested for the Mojo 2 using toslink. I have m2tech hiface 2 but thats coax only, and I feel Mojo 2 does better with optical.. I just can't believe this u2pro brings such substantial improvements for the price, thats great.