The weirdest behavior with Topping DACs and USB audio, please help!

[Hiilari]

Hello, greetings from Finland! I presume there's a ton of knowledge here on this forum, perhaps you can help me out.

I have a nice mid-fi home office setup with a laptop, some DACs, Musical Paradise small tube amp, good 2-way speakers and HiFiMan planars. Running Tidal in exclusive mode I really like the sound. I have a few DACs around including Topping D30 and D10, Dragonly Red, an older Campbridge Audio and some Focusrite audio interfaces in the basement studio.

Now, the trouble started when I got a docking station for my laptop so I could run a dual display setup. For some reason when the laptop is in the docking station both Topping DACs start creating loud humm or static. In fact, the loud hum comes from my speakers even with amp volume off! It plays music, but the loud hum is there too. With Dragonfly this does not happen, only with Toppings. I assumed this would some weird ground loop thing so I thought switching from Topping D30 to D10 might help since D10 has no power supply but uses USB power. But the hum was there sill, only quieter - but very audible. When I remove the laptop from the docking station and connect DAC directly to laptop, everything is fine. In the docking station things go haywire even if I'm actually using a USB port on my laptop for the DAC.

So somehow the Lenovo docking station + Topping DACs + Musical Paradise MP-301 is a nightmare combo. But I have no clue why. Any good tips from you guys?

 

[majingotan]

Here's your solution: https://www.audiosciencereview.com/...best-solution-for-me.10930/page-2#post-311321

Use D10 as a transport to D30

 

[Hiilari]

Here's your solution: https://www.audiosciencereview.com/...best-solution-for-me.10930/page-2#post-311321

Use D10 as a transport to D30

Ok, gotta try that one.... Back soon.

 

[Hiilari]

Here's your solution: https://www.audiosciencereview.com/...best-solution-for-me.10930/page-2#post-311321

Use D10 as a transport to D30

And it worked! Laptop -> USB cable -> D10 -> Optical SPDIF -> D30 -> RCA cables -> Amp combo makes the noize go away. One good DAC is now reduced to USB- to-SPDIF converted/re-clocker, but cutting the copper wire loop with optics did the trick. It's still kinda odd WHY this helped - what originally made the MP301 tube amp sound like broken radio even when volume completely off. Too much cable spaghetti + cheapo equipment I presume.

Thank you so much - this forum rules!

 

[Hiilari]

...and need to bring up this discussion again - the strange snap & crackle & pop has returned, as long as my Lenovo laptop is in its docking station. If I connect directly to laptop and use an USB hub then all is fine. What might cause this? One sympton is that an AudioQuest dragonfly connected to the USB post of the docking station got fried. Now, even with having an optical connection between two Topping DACs (first doing only USB to Toslink) the snap & crackle & pop are back. every 10 seconds or so, and loud enough to hear through music.

Should I replace the docking station? Or is this bad design? Any ideas?

 

[JustAnandaDourEyedDude]

...and need to bring up this discussion again - the strange snap & crackle & pop has returned, as long as my Lenovo laptop is in its docking station. If I connect directly to laptop and use an USB hub then all is fine. What might cause this? One sympton is that an AudioQuest dragonfly connected to the USB post of the docking station got fried. Now, even with having an optical connection between two Topping DACs (first doing only USB to Toslink) the snap & crackle & pop are back. every 10 seconds or so, and loud enough to hear through music.

Should I replace the docking station? Or is this bad design? Any ideas?

When did the previously mentioned (continuous?) hum switch to a periodic snap & crackle & pop?

The laptop is physically engaged with the docking station for all the independent tests suggested below for the presence of the noise. Everything is connected and powered on, except where specifically mentioned otherwise for the individual test. Needless to say, in every test the amp is powered on and connected to speakers at a volume at which you can clearly hear the noise. I do not think you need for music to play in many of the tests. Also, I think the tests are best when the D10 is plugged into a USB port in the laptop (or into a USB hub plugged into a port in the laptop), bypassing the dock entirely, since in a previous post you mentioned that the noise occurs even in this case.

(1) Is the noise present when only the amp is powered on and is disconnected from the D30?

(2) When everything is powered on and connected, but the amp is disconnected from the D30?

(3) As in (2) but the D30 is connected to the amp and is disconnected from the D10?

(4) When only your second (external) monitor is powered off (or better, its power cord unplugged)? With and without music playing.

(5) When the external monitor is powered on but unplugged from the docking station? With and without music playing.

(6) When the laptop is engaged with the docking station, but the docking station is unplugged from the wall power or surge protector?

 

[Hiilari]

Thanks for thorough questions! Lemme try to answer:

When did the previously mentioned (continuous?) hum switch to a periodic snap & crackle & pop?

When I replaced the Topping D30 DAC with D10 + D30 combo where D10 only provides USB-to-Toslink conversion. I previously thought this trick fixed the problem but I initially wasn't listening well enough. The continuous buzz was gone but during quiet passages the snap & crackle was there. Take out the docking station and all is well (except missing the second display....)


The laptop is physically engaged with the docking station for all the independent tests suggested below for the presence of the noise. Everything is connected and powered on, except where specifically mentioned otherwise for the individual test.

(1) Is the noise present when only the amp is powered on and is disconnected from the D30?

Nope. The amp itself is quiet. Well, to the extent of a small class-A tube amp is (Musical Paradise MP-301 with Russian 6L6's - have experimented with different tubes and god slightly different sound but no effect on the actual issue)


(2) When everything is powered on and connected, but the amp is disconnected from the D30?

No noise present. The snap & cracle comes only when music plays - as if the polluted electrics or ground loops or something messes up the DAC itself.


(3) As in (2) but the D30 is connected to the amp and is disconnected from the D10?

No noise present as in this scenario no music is playing.


(4) When only your second (external) monitor is powered off (or better, its power cord unplugged)?

Monitors seem to have no effect. Even if I physically disconnect BOTH monitors form both HDMI and mains, and leave music playing, the sound is c


(5) When the external monitor is powered on but unplugged from the docking station?

Same as above.


(6) When the laptop is engaged with the docking station, but the docking station is unplugged from the wall power or surge protector?

With this connection no noise is present. So the power supply of the docking station might be the culprit? I do have a surge protector but when connecting laptop's own power supply to the laptop form the surge protector, sound is clean.

 

[Berwhale]

Make and model of docking station?

I think a docking station (as opposed to a USB dock) is going to be the worst case scenario when it comes to cross talk and noise. Routing power, PCI-e, video, usb, etc. signals through a single connector is a recipe for disaster. Just getting all these signals to a single connector on the motherboard is a massive design challenge and will inevitably lead to compromises with trace length and signal isolation.

 

[Hiilari]

Make and model of docking station?

I think a docking station (as opposed to a USB dock) is going to be the worst case scenario when it comes to cross talk and noise. Routing power, PCI-e, video, usb, etc. signals through a single connector is a recipe for disaster. Just getting all these signals to a single connector on the motherboard is a massive design challenge and will inevitably lead to compromises with trace length and signal isolation.

I have a Lenovo ThinkPad Pro, here's a picture (sorry, the page is in Finnish ) https://www.verkkokauppa.com/fi/pro...-ThinkPad-Pro-Docking-Station-telakointiasema

Docking stations are IMHO quite essential for home office use (we all do home office over here as well...) and I couldn't have thought they mess up DIGITAL audio. I assumed, perhaps incorrectly, that USB bus buffers audio, and if it fails to do so, you simply have no audio. I use Tidal and exclusive mode and bit perfect and all. Or is the good-but-kinda-cheapo Topping and its wall wart PSU showing its limitations here? Interesting stuff...

 

[majingotan]

Make and model of docking station?

I think a docking station (as opposed to a USB dock) is going to be the worst case scenario when it comes to cross talk and noise. Routing power, PCI-e, video, usb, etc. signals through a single connector is a recipe for disaster. Just getting all these signals to a single connector on the motherboard is a massive design challenge and will inevitably lead to compromises with trace length and signal isolation.

Not necessarily that a docking station can cause those issues. Badly designed one like from OP can. I use docking station 24/7 with my laptop and my DAC have ZERO noise ZERO pops and clicks and a perfect DSD512 playback or DXD playback over USB.

 

[Berwhale]

Indeed, I have a Lenovo USB Pro Dock at home (which is no longer made)...

https://support.lenovo.com/gb/en/solutions/acc100184

And USB Hybrid Dock on my desk at work...

https://www.lenovo.com/gb/en/access...ocks-usb/TP-Hybrid-USB-C-Dock-UK/p/40AF0135UK

I think your 'docking station' is basically the same as my USB docks, it just has the additional connector for power. It's not like the old docks where multiple signal types were routed through a single multipin connector on the bottom of the laptop.

 

[Berwhale]

Not necessarily that a docking station can cause those issues. Badly designed one like from OP can. I use docking station 24/7 with my laptop and my DAC have ZERO noise ZERO pops and clicks and a perfect DSD512 playback or DXD playback over USB.

I am reminded of a discussion I once had with a laptop design engineer from Dell. This would have been well over 10 years ago when Dell transitioned from their D to their E Series laptops. The E Series required a completely different docking station which meant that my company had to replace several thousand of them at considerable expense. So I asked then Engineer about the reasons behind the change.

I was told that the primary driver for the change of dock design was the introduction of PCI-Express. PCI-Express runs at a much higher frequency than PCI and therefore required shorter trace lengths on the motherboard. In order to minimise trace lengths, the docking connector was moved to the centre of the motherboard. Previously, power and IO would have been routed to the outside edge of the motherboard, so this was a massive change in design philosophy and caused quite a few headaches for the engineers (a quite a bit of unreliability in the early models).

 

[JustAnandaDourEyedDude]

Thanks for thorough questions! Lemme try to answer:

Sorry, did not notice that you had replied with answers, because the reply is minimized along with my original post in your displayed post and I needed to expand it with a mouse click.

So, from your test outcomes it seems that the fault does not lie with RFI/EMI from the external monitors, nor with your MP tube amp, nor with either of the Topping DACs, nor with your laptop or its USB. Also, the outcome of the last test narrows the fault to the chain: power supply of dock -> dock -> dock connection to laptop -> dock connection processing on motherboard. Something in this chain (when it is powered up) is corrupting the USB audio processing and routing on your laptop motherboard. The signal is being corrupted upstream of the D10, because it is already present when transmitted through the optical interconnect. You might try plugging the dock into a surge protector and a different mains outlet using a long mains extension cord. You can try replacing the dock's power supply, then the dock with a new unit or preferably a new unit of a different dock model that is compatible with your laptop. Also, cleaning the physical connection between laptop and dock and checking for crimped wires or loose/broken/exposed connections or other physical deterioration in the part of that chain exterior to the motherboard. If the problem lies in the way the dock connection is processed and routed on the motherboard, then likely you would always have the noise if using a dock and playing music from that laptop. Upgrading the D10 to a D10S might conceivably help if the D10S has a better USB receiver/bridge (if the problem is USB jitter (timing), and not other bit corruption). If you take out the optical connection (in order to upgrade the D10 to a better DAC with a better USB receiver but with no optical out), you might get the hum back, which is probably a symptom of a ground loop. And your MP amp alas probably does not accept XLR input to eliminate ground loop issues.

Question: when everything is connected and powered up and the amp at the right volume, but you do not play any music, is the noise still present? I expect that the answer is that the noise is not present, because the DACs should anyway power down their outputs when they do not sense any USB bitstream, but I would just like to get your confirmation.

 

[Hiilari]

Sorry, did not notice that you had replied with answers, because the reply is minimized along with my original post in your displayed post and I needed to expand it with a mouse click.

So, from your test outcomes it seems that the fault does not lie with RFI/EMI from the external monitors, nor with your MP tube amp, nor with either of the Topping DACs, nor with your laptop or its USB. Also, the outcome of the last test narrows the fault to the chain: power supply of dock -> dock -> dock connection to laptop -> dock connection processing on motherboard. Something in this chain (when it is powered up) is corrupting the USB audio processing and routing on your laptop motherboard. The signal is being corrupted upstream of the D10, because it is already present when transmitted through the optical interconnect. You might try plugging the dock into a surge protector and a different mains outlet using a long mains extension cord. You can try replacing the dock's power supply, then the dock with a new unit or preferably a new unit of a different dock model that is compatible with your laptop. Also, cleaning the physical connection between laptop and dock and checking for crimped wires or loose/broken/exposed connections or other physical deterioration in the part of that chain exterior to the motherboard. If the problem lies in the way the dock connection is processed and routed on the motherboard, then likely you would always have the noise if using a dock and playing music from that laptop. Upgrading the D10 to a D10S might conceivably help if the D10S has a better USB receiver/bridge (if the problem is USB jitter (timing), and not other bit corruption). If you take out the optical connection (in order to upgrade the D10 to a better DAC with a better USB receiver but with no optical out), you might get the hum back, which is probably a symptom of a ground loop. And your MP amp alas probably does not accept XLR input to eliminate ground loop issues.

Question: when everything is connected and powered up and the amp at the right volume, but you do not play any music, is the noise still present? I expect that the answer is that the noise is not present, because the DACs should anyway power down their outputs when they do not sense any USB bitstream, but I would just like to get your confirmation.

Thank you so much, this is good info! In my current setup I never any get any snap & crackle with no music playing. So, could it be that it's the analog side of the Topping DAC that suffers from either ground loops or gets f*#d by the electric noise pollution from the docking station's broken/bad 135W power supply? I think I'll start by, as you suggest, by replacing the power supply, and play with surge protector on/off. Next would be to replace the wall-wart of the Topping with something sturdied and better regulated one.

 

[Mutias]

Hi

I had the same problem, but it got solved with the USB isolator, no need to fiddle with power.

https://www.starelec.fi/product_info.php?products_id=26217

BR
Matias