[Khragon]

Have you try contacting yulong directly?
http://www.yulongaudio.com/en/contact.asp

 

[blackie333]

Thank you for the suggestion. I have sent an e-mail message to the 3 addresses (wsz0304@vip.163.com, yulongaudio@foxmail.com, yulongaudio@qq.com) with request for help and link to my head-fi post containing problem description.
I am interested into whether someone will actually reply.

 

[Khragon]

I would also contact Grant Fidelity, even if you didn't buy from them, I think they are the official US rep for Yulong.
 
This is one of the reason I sold my DA8, Yulong isn't very good at customer service.

 

[infinity88]

  I would also contact Grant Fidelity, even if you didn't buy from them, I think they are the official US rep for Yulong.
 
This is one of the reason I sold my DA8, Yulong isn't very good at customer service.

No way. Unless the product was bought through them, they have no obligation.  The following is from their website: 
 
Note that your product must have been purchased from Grant Fidelity and we require dated proof of purchase before we can assist you with any warranty service.
Grant Fidelity doesn't service or provide advice to any products purchased from other vendors. Please do NOT contact us if your case falls into this category as we do not have resources to provide such free services. 
 
Best thing to do is what he's already done and provide links to this forum. It will affect sales if warranty on Yulong products isn't honored. I personally will not support Yulong any further if it turns out he's skimping on warranty. However, I'm confident he's going to help blacki333 out. I have corresponded with Rachel myself and it takes a few business days to get a reply most times. 
 
I myself don't even qualify for warranty from GF as I bought the item on sale/clearance:
 
1. Above Grant Fidelity warranty policy is only applicable to the purchase of brand new products directly from Grant Fidelity. Demos, clearance or on-sale item do not qualify for the above warranty.
 
Pretty useless coverage from GF if you ask me. But they are a small business and competition is tight.
 
 

 

[Aleksandr-Rus]

  Hello again,
I want to report that the sound quality of my DA8 unit has finaly improved, yet it took very long time (nearly a year) until it finally bested my internal soundcard in SQ. It remains a mystery to me how it's possible that it needed so much time to break-in.
Unfortunately it's not yet the happy ending of my DA8 story.
 
During the break-in period the noise floor became much lower and sound cleaner, which revealed other problem.
Now I can clearly hear high pitched background noise in headphones connected to internal headamp every time USB input is receiving signal(48kHz and higher) from PC.
My only choice for now is to use Optical SPDIF input, it produces clear sound without the background noise(up to 192kHz).
USB input is producing noise when it's receiving data via USB connection, even after I switch the input to some inactive(AES/EBU or coax) input, the noise can still be clearly heard in headphones connected to internal headamp.
 
To stop the noise, I have to stop/pause playback on the PC, use resampling to 44.1KHz or SPDIF optical input.
I have tested 3 different USB cables (pins 1&4 covered, separated power) with no success on 4 different PCs, so I'm quite sure it's DAC/Int.headamp related problem. The balanced output doesn't seem to be affected by the problem, only internal headamp.
The background noise can be clearly heard when playing PCM signal 48Khz and above, DSD128 DoP and all DSD native modes. The higher the PCM frequency or DSD mode, the more apparent the noise is. So DSD is useless, as is USB input (except signal 44.1 Khz).
 
I have started to consider buying external headamp, but I think it's not fair I have to buy other expensive device to fix a problem.
Wanted to use my DA8 as 2in1 solution via USB which is not possible
 
I have contacted my seller (Kidultdiagnostic.com) for help twice, after few messages they promissed to contact Yulong and organize my unit inspection and repair, but then they suddenly stopped responding.
 
 
 

I also found a trace of a review on the forum Rus:
Interference from a computer course. The different modes are different. Most likely the video card. I have everything exactly the same. The headphones hear digital interference from a computer via the built-in amp. Not much, but in total silence heard clearly. From different laptops no interference. With an external amplifier either. From the different components is, only different in nature and volume. For example minimize a window - the silence, turns around and go digital noise. Sometimes when you move the mouse heard. That is how all the symptoms you have.

 

[b0bb]

   
During the break-in period the noise floor became much lower and sound cleaner, which revealed other problem.
Now I can clearly hear high pitched background noise in headphones connected to internal headamp every time USB input is receiving signal(48kHz and higher) from PC.
My only choice for now is to use Optical SPDIF input, it produces clear sound without the background noise(up to 192kHz).
USB input is producing noise when it's receiving data via USB connection, even after I switch the input to some inactive(AES/EBU or coax) input, the noise can still be clearly heard in headphones connected to internal headamp.
 
To stop the noise, I have to stop/pause playback on the PC, use resampling to 44.1KHz or SPDIF optical input.
I have tested 3 different USB cables (pins 1&4 covered, separated power) with no success on 4 different PCs, so I'm quite sure it's DAC/Int.headamp related problem. The balanced output doesn't seem to be affected by the problem, only internal headamp.
The background noise can be clearly heard when playing PCM signal 48Khz and above, DSD128 DoP and all DSD native modes. The higher the PCM frequency or DSD mode, the more apparent the noise is. So DSD is useless, as is USB input (except signal 44.1 Khz).
 

 

 
You may have a noisy USB port on your computer.
 
Try plugging a hub into the usb port of your computer and connect the Yulong's usb port to the hub.
 
A self powered USB hub is recommended for this effort.
 
Put the computer and Yulong on separate powerstrips, the powerstrip should preferaby have some sort of noise filtering.

 

[wsz0304]

The problem is that the ground loop noise, good ground, or you can disconnect the ground.
And the product does not matter, he speaks, there is no fiber, because fiber can disconnect the ground wire.

 

[blackie333]

Thank you for your advices guys. I have received several replies from Yulong support, all are directed towards idea I am facing grounding loop issue.
So today I have tried to test whether the noise issue can be caused by the grounding loop.
For now I'm not so sure it is the problem reason, I will try to explain why.
 
SETUP:
I don't have any external headamp, so my whole setup is PC(or notebook) + DAC + headphones.
I don't have any special USB card in PC, so I have to use standard USB3.0 ports(PC) or USB 2.0 (notebook).
PC power supply is Seasonic Platinum 660 (quite good).
 
TEST:
1. If I use normal generic USB cable I can hear usual humming noise(more bass/medium freq. based with occational cracks) in headphones ALL THE TIME the cable is connected to DAC. It's apparent, but quite tolerable.
 
2. If I use special USB cable with 5V power pin disabled(have 2 of them), the noise is totally different.
I can hear much stronger background HIGH FREQUENCY noise like OSCILLATOR generated, it's constant without any cracks like with normal generic USB cable.
This noise is also louder and not tolerable to my ears. And can ONLY be heard when PC(or notebook) is sending data via USB cable to the DAC. If I stop/pause music in foobar the noise stops too.
Maybe interesting note is if I use signal frequency 44.1 the noise disappears.
 
THINGS I HAVE TRIED AND PLAN TO TEST:
I have tested my PC connected to the same, or different power outlet from DAC without any positive effect.
My notebook(ON BATTERY) connected to DAC via special cable is causing the same issue.
Tested connection via USB 2.0 hub powered from the same outlet as DAC without success, will test more combinations later.
 
Tomorrow I plan to borrow SPDIF coaxial cable for test, if the issue is really a grounding loop I presume the noise should also affect this connection between PC and DAC too, or?

 

[earfonia]

Just posted my Yulong DA8II review:
http://www.head-fi.org/t/779702/yulong-da8ii-in-depth-review

 

[infinity88]

DA8 review:
 
For the past few weeks, I've had the experience of using a da8 in my chain of components. My chain goes from laptop to da8 via usb, then to a tube amp (integrated), and off to a very good pair of speakers. Originally, it was a cheap usb/spdif converter, to a digital preamp, and then to the same tube amp and speakers.
 
Out of shear intrigue, I sat positing the question of whether or not the system (as it was) could be improved. It already sounded amazing, quite balanced and fairly neutral throughout the frequency range, a tad on the dark side, which is the way I prefer it. Well, since money wasn't a concern at the time, I let curiosity get the best of me and I ordered a da8, one of the last few they claim they have in stock since the da8 ii was released. 
 
My first thoughts were that it's a well built unit, with a nice design and quality feel. I wasn't thrilled about the lack of remote control but sound quality is the forefront of my priority list and these things can be worked around in any case. 
Here are my thoughts on the sound:
 
Pros:
 
The sound itself is quite full, it has a good balance of frequencies, detail, music sounds alive and crisp, great bottom end, the output of the dac has plenty of gain (I don't have to turn up my amp as high as I did when using the digital preamp). 
This dac supports DSD, but since the industry doesn't...this isn't much of a consolation. Just try finding a DSD file online :/  
 
Cons:
 
The first thing I noticed when I fired up the da8 is my soundstage morphed from amazing 3D in my previous setup, to a unison kind of soundstage. The difference is astonishing, literally night and day. I did A/B comparisons on multiple music sources switching from the da8 to the onboard burr brown dac on my preamp. Where the vocals would previously be directly in front of me, or to the left or right (depending on the source) and slightly behind the speakers, and the acoustic guitar slightly to her right with the old dac, with the da8, the vocals and guitar now come from the left and right speakers only. The 3D imaging has been completely obliterated. 
 
 
It seems people here have had good experiences with this dac. I wonder though if anyone else has experienced the break up of 3D imaging, or if the imaging could possibly fix itself over time. Someone posted that it took nearly a year for their da8 to break in and sound better than the sound card in their computer. It's not worth it to wait for the sound to magically acquire sonic benefits that my system already has, and without the convenience of a remote. 
 
Summary: The sound, for whatever reason is better on my old preamp, and I see no reason to keep this dac. The da8 will be heading off to classified heaven to recoup some costs, fortunately, I got it on sale and will therefore lose a bit less than if I paid full price.

 

[earfonia]

  DA8 review:
 
.....
 
Cons:
 
The first thing I noticed when I fired up the da8 is my soundstage morphed from amazing 3D in my previous setup, to a unison kind of soundstage. The difference is astonishing, literally night and day. I did A/B comparisons on multiple music sources switching from the da8 to the onboard burr brown dac on my preamp. Where the vocals would previously be directly in front of me, or to the left or right (depending on the source) and slightly behind the speakers, and the acoustic guitar slightly to her right with the old dac, with the da8, the vocals and guitar now come from the left and right speakers only. The 3D imaging has been completely obliterated. 
 
 
It seems people here have had good experiences with this dac. I wonder though if anyone else has experienced the break up of 3D imaging, or if the imaging could possibly fix itself over time. Someone posted that it took nearly a year for their da8 to break in and sound better than the sound card in their computer. It's not worth it to wait for the sound to magically acquire sonic benefits that my system already has, and without the convenience of a remote. 
 
Summary: The sound, for whatever reason is better on my old preamp, and I see no reason to keep this dac. The da8 will be heading off to classified heaven to recoup some costs, fortunately, I got it on sale and will therefore lose a bit less than if I paid full price.

 
Wow, that's doesn't sound good. I've compared some desktop DACs around DA8 category, but never noticed the 3D holographic imaging destroyed when switching to DA8.  Yes, it is not the best DAC for holographic imaging, but it is not that bad either. And yes, imaging improved on DA8 II, but it is not that bad on DA8.
Personally I don't believe those 1 year break-in. 1 day usually enough for DAC.
 
Could it be there is something wrong with your DA8?

 

[tolik212]

The channel crosstalk of DA8 ll is about 130dB, THD =0.0002% - well below the threshold level of some audio analysers. I`m just can't to imagine how it can to destroy or to alter the stereo image.
That DAC will benefit from usage with the dual mono amp, or 2 separate mono blocks.

 

[infinity88]

   
Wow, that's doesn't sound good. I've compared some desktop DACs around DA8 category, but never noticed the 3D holographic imaging destroyed when switching to DA8.  Yes, it is not the best DAC for holographic imaging, but it is not that bad either. And yes, imaging improved on DA8 II, but it is not that bad on DA8.
Personally I don't believe those 1 year break-in. 1 day usually enough for DAC.
 
Could it be there is something wrong with your DA8?

 
I wouldn't think there's something wrong with the dac. And really, it does sound good, regardless of the mono biased sound signature. But if the 3d imaging goes, so does the dac.
 
I believe in "burn in" because I experienced it when I replaced capacitors in my tube amp and noticed a massive change after a couple hundred hours. There are a lot of capacitors in the da8, so possibly it needs more time to burn in.
 
I've put the dac up for sale, but in the meantime, I'll feed it music 24/7 on my second system, and see if there is any change in a week or two. 

 

[Priidik]

 I did A/B comparisons on multiple music sources switching from the da8 to the onboard burr brown dac on my preamp. Where the vocals would previously be directly in front of me, or to the left or right (depending on the source) and slightly behind the speakers, and the acoustic guitar slightly to her right with the old dac, with the da8, the vocals and guitar now come from the left and right speakers only. The 3D imaging has been completely obliterated. 

Which Burr Brown dac is it?
 

  The channel crosstalk of DA8 ll is about 130dB, THD =0.0002% - well below the threshold level of some audio analysers. I`m just can't to imagine how it can to destroy or to alter the stereo image.
That DAC will benefit from usage with the dual mono amp, or 2 separate mono blocks.

 
In my experience these numbers are mostly good for bragging rights. The crosstalk is not the only parameter to alter soundstage.
DA8 was the best dac in my possession at quoted specs, but one of the worst sounding in 500€+ range.

 

[infinity88]

  Which Burr Brown dac is it?
 
 
In my experience these numbers are mostly good for bragging rights. The crosstalk is not the only parameter to alter soundstage.
DA8 was the best dac in my possession at quoted specs, but one of the worst sounding in 500€+ range.

I'm running an old avm 20. It has audiophile grade burr brown op-amps and dacs throughout. The system was well designed in layout and components which is why it received many awards and steep price of over $3000 back in 2002. 
 
For the money I would think there are a lot of better dacs out there. It seems this one has received a bit of hype.