Douk Audio U2Pro Digital Interface Upgrade is Being Planned and Waiting for Your Advice!

[Douk Audio]

Bump @Douk Audio

Hi, thank you so much for your attention! Today I can finally happily reply to all of you, U2pro is finally released (some descriptions will be modified next Monday.) ! It will be released on all platforms next week! More information please click: https://www.ebay.com/itm/267297001829

 

[Douk Audio]

Any news on the release @Douk Audio ?

Yeah! Now I can finally happily reply to you, U2pro is finally released (some descriptions will be modified next Monday.) ! It will be released on all platforms next week! More information please click: https://www.ebay.com/itm/267297001829

 

[L-Train]

Hi, thanks for your attention and so sorry for the delay! Today I can finally happily reply to all of you, U2pro is finally released (some descriptions will be modified next Monday.) ! It will be released on all platforms next week! More information please click: https://www.ebay.com/itm/267297001829

This is great, thanks! I really appreciate the addition of the isolation transformer for the coaxial output.

I noticed that this new model doesn't have separate clocks for 44.1/48 kHz (and their multiples), so I'm assuming it uses the XU316's secondary PLL to generate those clocks. Would you happen to have more in-depth measurements of the toslink and coaxial output jitter that you can share? The 75ps typical jitter stated is great and about the same as Topping's U90, but seeing the measurements would make this an immediate buy for me.

 

[hobbitz]

Is there a way to use external LPS on U2 Pro XU316 ?

 

[Douk Audio]

This is great, thanks! I really appreciate the addition of the isolation transformer for the coaxial output.

I noticed that this new model doesn't have separate clocks for 44.1/48 kHz (and their multiples), so I'm assuming it uses the XU316's secondary PLL to generate those clocks. Would you happen to have more in-depth measurements of the toslink and coaxial output jitter that you can share? The 75ps typical jitter stated is great and about the same as Topping's U90, but seeing the measurements would make this an immediate buy for me.

Hi, thank you for your attention and questions. Last month, I emailed Amir requesting a review, and with his approval, I've sent him a sample. Let's look forward to his test.

 

[Roland68]

Is there a way to use external LPS on U2 Pro XU316 ?

You simply connect the two data lines and the power supply's negative terminal from the source to the U2Pro USB port. From the LPS, connect the power supply's positive and negative terminals to the U2Pro USB port.
If you can't find a ready-made cable, you'll have to make one yourself.

 

[hobbitz]

You simply connect the two data lines and the power supply's negative terminal from the source to the U2Pro USB port. From the LPS, connect the power supply's positive and negative terminals to the U2Pro USB port.
If you can't find a ready-made cable, you'll have to make one yourself.

Thanks for the suggestion. I have done it using a cheap USB C splitter and blocking the +5V in USB cable as suggested in 6moons audio in this link
https://6moons.com/audioreviews/elijah/2.html

 

[danadam]

Douk Audio U2 PRO XMOS XU316

Chain: USB -> Douk Audio U2 Pro -> optical -> RME Adi-2 Pro -> USB

RME's bittest files pass (44.1k, 96k, 192k at 16-bit and 24-bit).

Here's 1000.07 Hz tone (it is self-dithering) at different sampling rates:


Here's SMPTE 60 Hz +7 kHz with dither at 44.1k and 48k:

 

[gino1961]

Douk Audio U2 PRO XMOS XU316

Chain: USB -> Douk Audio U2 Pro -> optical -> RME Adi-2 Pro -> USB

RME's bittest files pass (44.1k, 96k, 192k at 16-bit and 24-bit).

Here's 1000.07 Hz tone (it is self-dithering) at different sampling rates:
View attachment 486972 View attachment 486973 View attachment 486974 View attachment 486975

Here's SMPTE 60 Hz +7 kHz with dither at 44.1k and 48k:
View attachment 486976 View attachment 486977

Hi very interesting and impressive Which usb source are you using ? Thank you

 

[danadam]

Hi very interesting and impressive Which usb source are you using ? Thank you

It was desktop PC with Linux, the test signals were generated with SoX and played through aplay (ALSA command line player). I didn't use REW's generator because then it produces even harmonics for some reason:

 

[gino1961]

It was desktop PC with Linux, the test signals were generated with SoX and played through aplay (ALSA command line player). I didn't use REW's generator because then it produces even harmonics for some reason:
View attachment 487113

Hi thank you very much for your kind reply
Is SoX this one ? https://sourceforge.net/projects/sox/
the results are really impressive

 

[danadam]

Is SoX this one ? https://sourceforge.net/projects/sox/

Yes.
The files were generated like this:

sox -r44.1k -c2 -n -b24 test1.wav synth 60 sin 1000.07 norm -.0004 fade h .2 0 .2
sox -r44.1k -c2 -n -b24 test2.wav synth 60 sin 60 sin 7k norm -2 remix 1v1,2v.25 remix 1 1 norm -.0004 fade h .2 0 .2 dither

 

[gino1961]

Yes.
The files were generated like this:

sox -r44.1k -c2 -n -b24 test1.wav synth 60 sin 1000.07 norm -.0004 fade h .2 0 .2
sox -r44.1k -c2 -n -b24 test2.wav synth 60 sin 60 sin 7k norm -2 remix 1v1,2v.25 remix 1 1 norm -.0004 fade h .2 0 .2 dither

Hi thank you very much again ... this is beyond my skills
i would like to start some measurements mainly on power supplies and line preamps/buffer but it is not that easy when the ripple and noise and THD are very low

 

[Schlippwhip68]

I have Douk Audio U2 Pro 2025 on the way and am looking upgrading the ocilator clock. There are a number of choices but the most recommended seems to be the Crystek 957. There are a few different variations of this clock with difference in the MHZ. 12 being the lowest rising to 49 mhz.
Can someone enlighten me as to the best choice ie circuit match within this range from Crystek?
I can see the original clock is 24mhz. Would going with an higher clock speed be of any improvement or would it be a strain on the surrounding circuits which I suspect it might.

I have this one in mind as well as the standard XO and VCXO 957 depending on which is more system matched.

22.5792MHz 24.576Mhz MUSETEC custom clock upgrade Crystek 957

https://a.aliexpress.com/_Eu2qtcG

Perhaps Douk Audio could confirm?

If the U2 Pro DDC needs to be synchronized via a PLL, a VCXO is the necessary choice. If it operates independently, a standard XO may suffice….apparently but I am not sure if the the Douk Audio is as such for VCXO.
Again, confirmation would be great here.

 

[Roland68]

I have Douk Audio U2 Pro 2025 on the way and am looking upgrading the ocilator clock. There are a number of choices but the most recommended seems to be the Crystek 957. There are a few different variations of this clock with difference in the MHZ. 12 being the lowest rising to 49 mhz.
Can someone enlighten me as to the best choice ie circuit match within this range from Crystek?
I can see the original clock is 24mhz. Would going with an higher clock speed be of any improvement or would it be a strain on the surrounding circuits which I suspect it might.

I have this one in mind as well as the standard XO and VCXO 957 depending on which is more system matched.

22.5792MHz 24.576Mhz MUSETEC custom clock upgrade Crystek 957

https://a.aliexpress.com/_Eu2qtcG

Perhaps Douk Audio could confirm?

If the U2 Pro DDC needs to be synchronized via a PLL, a VCXO is the necessary choice. If it operates independently, a standard XO may suffice….apparently but I am not sure if the the Douk Audio is as such for VCXO.
Again, confirmation would be great here.

It would have been better if they had supported a standard 10 MHz clock.

If you really want an upgrade, you should probably order the crystal from an official distributor, or be able to measure whether it has the necessary technical specifications/accuracy; otherwise, it will be a downgrade.

 

[Schlippwhip68]

It would have been better if they had supported a standard 10 MHz clock.

If you really want an upgrade, you should probably order the crystal from an official distributor, or be able to measure whether it has the necessary technical specifications/accuracy; otherwise, it will be a downgrade.

Reading up now on this. Thanks

 

[Perpetual Novice]

Hello! I'm new here and a complete noob. I came across this thread looking for info around upgrading the clock. I had an online chat with Douk Audio Customer Service a few days ago. I thought it could be possibly be helpful, apologies if it isn't.

"Hi, to replace the original crystal oscillator, the specifications must be 24MHz/1.8V. The parameters of the oscillator from the link you shared differ too significantly from the original, so we do not recommend using it...We will soon be launching new versions of the U2 PRO: a TCXO version and a Femto-second version. You may want to consider these for a future upgrade...If you decide to replace it yourself, we suggest you choose a high-precision, temperature-compensated crystal oscillator."

That's all I've got, sadly i don't have any further info and I'm unqualified suggest any potential replacements. Hope this helps a little in any case.

Perhaps @Douk Audio can expand further?

 

[gino1961]

Good morning, and excuse me if I ask an ignorant question.
I see an effort to get the most accurate clock possible within the DDC interface.
But if the following DAC uses its own internal clock, does it make sense to seek maximum clock precision in the interface ?
And how can i know if a DAC uses its own internal clock ?
The good thing is that if it does, the quality of the source should matter less, right ?

 

[Roland68]

Good morning, and excuse me if I ask an ignorant question.
I see an effort to get the most accurate clock possible within the DDC interface.
But if the following DAC uses its own internal clock, does it make sense to seek maximum clock precision in the interface ?
And how can i know if a DAC uses its own internal clock ?
The good thing is that if it does, the quality of the source should matter less, right ?

Every decent DAC has its own crystal oscillator, regardless of whether it costs €70 or €1000.

To put it simply, it's important to preserve the signal as much as possible during transmission and to minimize any interference, including the clock signal.
Imagine it like a game of telephone. Imagine two lines of 10 people each. In one line, you put cotton wool in the ears of the people and a large portion of mashed potatoes in their mouths. What do you think the result would be?

 

[gino1961]

Every decent DAC has its own crystal oscillator, regardless of whether it costs €70 or €1000.

To put it simply, it's important to preserve the signal as much as possible during transmission and to minimize any interference, including the clock signal.
Imagine it like a game of telephone. Imagine two lines of 10 people each. In one line, you put cotton wool in the ears of the people and a large portion of mashed potatoes in their mouths. What do you think the result would be?

Hi thank you very much for your kind and valuable advice.
I had to ask because some time ago I read a review of a USB to SPDIF/AES_EBU converter that, according to the experts, was pretty much the best for its time... from Berkeley Audiodesign Company, shown below.

Alpha USB Series 2 — Berkeley Audio Design

www.berkeleyaudiodesign.com

Obviously, among other things, it also reclocked the input signal and output it very precisely.
Well, at a certain point, the reviewer said he'd tried the unit with different sources like a PC, CD player, DVD player, etc., of different prices and therefore quality.
And he claimed that the differences in sound were so small they were difficult to perceive.
This has always fascinated me.
And I wonder if such performance is now offered at lower prices. I certainly don't have a system that justifies spending so much on a component. I'm not a purist who thinks it's DSD or nothing. i like just decent sound.
Thanks again and best regards, Gino