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Audio-GD Reference 5.2 (New Balanced 4x PCM1704UK DAC)
Feb 3, 2013 at 11:01 AM Post #241 of 300
Help! I'm having a problem with hum/buzz from my Reference 5.2
 
I don't hear it when using balance XLR connections, only RCA. It's audible (just) when connected to my Violectric v200 with the volume cranked right up, but much more noticeable with my tube amp. At beyond normal listening levels it's actually pretty loud.
 
I've checked my other two DACs and both are completely silent, so it only happens with the 5.2. My impression is that it gets gradually worse the longer the unit is running. I assumed at first that I had a faulty tube but after checking I've concluded that it's definitely the DAC and I can even hear the hum through headphones when the amp is powered down. The hum is much more noticeable when the DAC is set to the high output setting - it becomes quite an angry buzz at full volume (with no music playing). It is loud enough that I can just hear it during quiet passages of music, although the sound is otherwise good. It's sufficiently annoying that I don't really want to use it with my tube amp.
 
Any thoughts? Has anyone else experienced this problem? The DAC is connected to my Mac Power Book via USB.
 
Feb 4, 2013 at 3:11 PM Post #242 of 300
Does the DAC still make a buzzing sound if there are no inputs feeding it?
 
Feb 5, 2013 at 6:49 AM Post #244 of 300
Quote:
painterspal said:
Yes it does. By contrast, my cheap and cheerful Audio GD 15.1 is completely silent.
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Sounds like a ground loop.  Try an audio isolation transformer in series with the RCA audio lines from DAC to AMP if you have one on hand.  I keep one around for a troubleshooting tool.
 
You can get an audio isolation transformer for about $10 or even as low as $5 on eBay, incl. shipping-  they also sell them at car stereo places, though the price may be higher.  Radio Shack used to have some too, not sure if they still do.
 
If the transformer eliminates the hum, that confirms there's a ground loop.  You probably don't want to leave it in the circuit, these transformers do degreade the sound a little, although they are actually pretty clean considering their low price.
 
There's various ways to get rid of ground loops-  SEE http://passlabs.com/articles/ground-loops
 
And for more info see  http://www.epanorama.net/documents/groundloop/
 
What may be happening is both amp and DAC are grounded to the third pin AC ground as well as signal ground between the amp and DAC; this is a ground loop and can induce a hum.  You don't hear it on the balanced XLR lines because the signal in a balanced circuit is not referenced to chassis ground like it is in an unbalanced RCA cable type of circuit.
 
Feb 5, 2013 at 4:55 PM Post #245 of 300
Many thanks for the suggestion. I had wondered about whether it might be a ground loop, but I'd discounted it because the other DAC worked fine. Is it possible for one component to exhibit a ground loop buzz/hum, but not another, even though they're connected in the same way?
 
It would certainly be good to know that the 5.2 wasn't faulty and that something else was to blame, although I remember reading somewhere that ground loops can be troublesome to cure. Anyway, I'll try and find an isolation transformer and will report back.
 
Feb 6, 2013 at 5:45 AM Post #246 of 300
Quote:
painterspal said:
 Is it possible for one component to exhibit a ground loop buzz/hum, but not another, even though they're connected in the same way?
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Sure.  All depends on how things are wired up INSIDE the component.
 
Feb 16, 2013 at 9:59 PM Post #248 of 300
Further troubleshooting revealed that the 'Soundstage shift' issue which occurs on the TENOR 8802 USB does not occur with 16bit/44 files or MP3's.  Issue does occur with 24bit/96 and 24/192 files. Can anyone shed some light as to why this would be the case?
 
Anyone who has a USB32 chip currently in any of the Audio-gd DAC's, can you confirm whether the issue is resolved?  The USB32 w/ TCXO upgrade is something I am leaning towards purchasing once Kingwa returns from his Chinese New Year stooper but confirming that the issue is resolved would be comforting.  Thanks.
 
Apr 8, 2013 at 6:41 AM Post #249 of 300
Hey rezolver, I know your last post was a couple of months ago, but I had the same 'soundstage shift' issue with my SA-1 DAC. In my case the intermittent channel imbalance almost drove me insane. Troubleshooting was a nightmare of switching amps, tubes, cables, headphones, DAC's, media players and any other variables in the chain. The common denominator was always the SA-1. I was finally able to swap my SA-1 for an SA-1.32 and I have not experienced the issue since changing. I had a feeling the whole time that the TE8022 was to blame, convincing Kingwa and the retailer was another matter though. It was ultimately rewarding to resolve this issue with an otherwise fine sounding DAC.
 
Apr 8, 2013 at 7:21 AM Post #250 of 300
Quote:
carlchip78 said:
Hey rezolver, I know your last post was a couple of months ago, but I had the same 'soundstage shift' issue with my SA-1 DAC. In my case the intermittent channel imbalance almost drove me insane. Troubleshooting was a nightmare of switching amps, tubes, cables, headphones, DAC's, media players and any other variables in the chain. The common denominator was always the SA-1. I was finally able to swap my SA-1 for an SA-1.32 and I have not experienced the issue since changing. I had a feeling the whole time that the TE8022 was to blame, convincing Kingwa and the retailer was another matter though. It was ultimately rewarding to resolve this issue with an otherwise fine sounding DAC.
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Could you post some comments on the SA-1 compared to your other DACs?
I cannot really get a proper idea of its voicing...
 
Apr 8, 2013 at 2:17 PM Post #251 of 300
Hi carl.  That is great to hear about USB32 solving the 'stage shift' issue.  It is frustrating when time and energy is put into troubleshooting and replicating the issue and the manufacture does not want to listen :|. 
Did you end up purchasing a USB32 board to replace your Tenor?  Did Kinga provide any sort of discount?
 
I find the TENOR 8802 implementation to be abysmal at best. HA.  To add fuel to the fire, when the DAC was turned on and connected via USB and my PC was rebooted, it would prevent the system from posting.  More headaches to deal with.  By that point I had enough. 
 
Does the USB32 exhibit the same reboot issue by chance?  I read somewhere that Kingwa recommends the DAC be turned off prior to a system restart.  I am sure the suggestion was made to prevent a 'no post' issue or other such occurrences.

Because of my experience with TENOR 8802 implementation, I decided against going with the USB32 implementation from Audio-gd.  Instead, based on a recommendation, I purchased a V-Link 192 which I am really happy with.  All I need now is a DIR9001 board :)
 
Does your SA-1.32 include the WM8805 or DIR9001 digital board?  I also see that it is a Diamond Diff. design.  My ROC SA is also a Diamond Diff. design and I really enjoy its sound.  I am sure the pairing would sound fantastic.
 
Cheers!
 
Apr 8, 2013 at 10:31 PM Post #252 of 300
Quote:
rezolver said:
 
Does the USB32 exhibit the same reboot issue by chance?  I read somewhere that Kingwa recommends the DAC be turned off prior to a system restart.  I am sure the suggestion was made to prevent a 'no post' issue or other such occurrences.

 
Cheers!
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I advice restart the USB device, because in our most USB32 device have not connect the +5V from computer for less disturb ,  the best operate is the USB device power on after the computer .
 
Apr 9, 2013 at 9:05 AM Post #253 of 300
Rezolver, I was lucky enough to purchase my DAC through a retailer in Australia and they were great throughout the whole process, actually so was Kingwa. Eventually I was able to do a straight swap for the revised unit.
In answer to your other questions, I never did experience the 'no post' issue. I think my DAC came with the DIR9001 board.
 
Sep 2, 2013 at 12:24 PM Post #255 of 300
PCM1704UK you mean 
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