xyrium Posted January 25, 2017 Share Posted January 25, 2017 So, I have a Focusrite 2i2 that I use for connecting a Mic and Guitar and producing through simulators, and I have a Teac UD-301 strictly for listening to WAVs. Both of them are dead silent, no buzzing, hissing, or any other annoyances. I then purchase a Nuprime DAC-9, thinking I would improve on the excellent performance of the Teac (regardless of its digital volume). Unfortunately, I've been through hell and back trying to eliminate the buzz that the new unit exhibits once a USB cable is connected. I've gone through isolation transformers on the power cord, I purchased a standalone PCIE USB card, tried a new Pangea CU USB cable, updated drivers where possible, disconnected fans within the PC chassis, unplugged all drives but the OS (Win 10), and I pulled out my video card and ran off of built in video on the MB. Then I connected the unit to a laptop running on battery. That last step eliminated the noise. Plugged in the power supply and the noise returned. So, I decided to reconnect it to my PC once again, but I plug it's (the DAC) power cord into a cheater plug (removes ground), and the noise disappeared. So, sorry this was long, but no other device needed a ground lift, so I'm of the opinion that there's an issue with the new DAC. Does this sound about right? Thanks! Link to comment
Middy Posted January 27, 2017 Share Posted January 27, 2017 Ground loop? Sent from my SM-G900F using Computer Audiophile mobile app Link to comment
wgscott Posted January 27, 2017 Share Posted January 27, 2017 Sounds like the Teac has (better) galvanic isolation. Or does the new dac have a ground plug but the teac does not? Nope. Teac is grounded: Link to comment
xyrium Posted January 27, 2017 Author Share Posted January 27, 2017 Ground loop?Sent from my SM-G900F using Computer Audiophile mobile app Yep, that's what I'm assuming, but only happens on one device and goes away with a ground lift. Sounds like the Teac has (better) galvanic isolation. Or does the new dac have a ground plug but the teac does not?Nope. Teac is grounded: Exactly right, and thus why I'm baffled by the problem, unless there's something going on inside that new DAC. Link to comment
mmerrill99 Posted January 27, 2017 Share Posted January 27, 2017 Does the ground lift change the sound of the Teac in any way? Link to comment
xyrium Posted January 27, 2017 Author Share Posted January 27, 2017 Hmm, hadn't tried that. Link to comment
mmerrill99 Posted January 27, 2017 Share Posted January 27, 2017 Let us know if it had an effect or not if you do try the ground lift on the Teac? Link to comment
One and a half Posted January 27, 2017 Share Posted January 27, 2017 The photos for the Nuprime don't quite reveal the type of the USB B connector. It 'looks' as though the shell connector is crimped onto the frame of the DAC, which is grounded to safety earth. That's where the ground loop comes from. The Teac uses a plastic shell, which insulates the USB cable shell from the frame and safety ground. This is also the practice for Grace Design m920 USB connector, and just looked at Yggdrasil, hard to tell, but looks like a layer of plastic around metal too. From here? Return the Nuprime as unsuitable or buy an Intona or just keep using the Teac. AS Profile Equipment List Say NO to MQA Link to comment
mmerrill99 Posted January 27, 2017 Share Posted January 27, 2017 The photos for the Nuprime don't quite reveal the type of the USB B connector. It 'looks' as though the shell connector is crimped onto the frame of the DAC, which is grounded to safety earth. That's where the ground loop comes from. The Teac uses a plastic shell, which insulates the USB cable shell from the frame and safety ground. This is also the practice for Grace Design m920 USB connector, and just looked at Yggdrasil, hard to tell, but looks like a layer of plastic around metal too. From here? Return the Nuprime as unsuitable or buy an Intona or just keep using the Teac. Good sleuthing. Still interested in whether the ground loop expresses itself with the Teac in other ways - like a flatness in soundstage & reduction in dynamics Link to comment
Middy Posted January 27, 2017 Share Posted January 27, 2017 wrap a bit of electrical tape on the end of the of the usb cable see what happens... Sent from my SM-G900F using Computer Audiophile mobile app Link to comment
mmerrill99 Posted January 30, 2017 Share Posted January 30, 2017 Hmm, hadn't tried that. Still haven't tried it? Link to comment
xyrium Posted February 5, 2017 Author Share Posted February 5, 2017 Holy moly, I'll try this today. I've been allowing this to slide this week since I put a HumX inline with it's power cord. Edit: I couldn't wait to try this, so I tried electrical tape, just 1 wrap of Scotch Super 33+ and it wouldn't fit. Then I tried Teflon tape, but the noise still existed. It's not overbearing, but it's clearly audible. Reinsert the HumX and it goes away. Everything is plugged into the same out via a power strip, Tripplite Isobar. ype of the USB B connector. It 'looks' as though the shell connector is crimped onto the frame of the DAC, which is grounded to safety earth. That's where the ground loop comes from. The Teac uses a plastic shell, which insulates the USB cable shell from the frame and safety ground. This is also the practice for Grace Design m920 USB connector, and just looked at Yggdrasil, hard to tell, but looks like a layer of plastic around metal too. From here? Return the Nuprime as unsuitable or buy an Intona or just keep using the Teac. Link to comment
Middy Posted February 5, 2017 Share Posted February 5, 2017 https://pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html If your US based I use this This is cheap and we'll made http://www.atlhifi.com/shop/fully-assembled-devices/dc-blocker-trap-filter-assembled-in-case/ Intona is nice... Sent from my SM-G900F using Computer Audiophile mobile app Link to comment
xyrium Posted February 5, 2017 Author Share Posted February 5, 2017 Thanks Middy. I think the HumX is getting the job done, and I'd rather not mess with the USB signal. I've read up on the CMX though, and it does seem nice if I needed multiple device filtering. My Fluke is a fairly new 87 model, and it's measuring 0 to negative values on DC on the outlets, so I doubt offset is a problem. While not the top of the line, the 87 is still a fairly decent unit. So, it looks like I need to suck it up and keep the HumX in line, or swap the DAC9 for a new one (as they've offered, unless is a design defect). Thanks for everyone's help! I'll keep the thread updated if there's a change! https://pooraudiophile.com/2015/03/how-to-fix-dc-offset-and-transformer.html If your US based I use this This is cheap and we'll made DC Blocker Trap Filter – Assembled in Case | ATL Hi-Fi Audio Company Intona is nice... Sent from my SM-G900F using Computer Audiophile mobile app Link to comment
Middy Posted February 5, 2017 Share Posted February 5, 2017 Your very welcome. Good luck Dave Sent from my SM-G900F using Computer Audiophile mobile app Link to comment
xyrium Posted February 7, 2017 Author Share Posted February 7, 2017 Ok, update. I opened the case on the DAC9 and started poking around with my MM for continuity to ground. The chassis ground lug and the unit's receptacle ground are intact. However, using either the receptacle ground or the chassis ground, I do not obtain continuity to the USB port shell, which is metal. More oddly, I DO obtain continuity between the chassis ground or receptacle ground and the positive lugs on the XLR and RCA outputs. Why would the hots be grounded? Does any of this sound odd to folks here as well? Thanks! Link to comment
comedus06 Posted February 7, 2017 Share Posted February 7, 2017 I have a similar USB buzzing issue though in a different part of the chain. I recently purchased an Minix NEO Fanless PC (MINIX NEO Z83-4) to use as a HQ Player NAA. It comes with a 12v 3A switching power supply (planning to purchase a LPS later). When I connect the USB to the DAC, immediately a ground loop type buzz comes on. I've tried both a powered and a non-powered USB cable since my DAC has the Amanero board that doesn't need power from the USB. I also tried plugging the adapter into the HumX (which I had lying around from before) and the buzzing still shows up. Any suggestions on how to fix this (or if it's worth fixing) or should I just return the Minix and find a similar alternative? Oh - my DAC has no hum/buzzing issues when a different PC, Mac or the Sonore Microrendu is connected. Link to comment
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