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1kHz + Harmonics Noise during playback via USB

P

Plompudu

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I've got the Issue that when i try to play audio via USB I'm getting a annoying noise that i can't seem to fully fix.

From what i found out could it be caused by the USBs "Framerate", which is 1kHz, but how can i stop it?
The only Idea i got is getting a powered USB-Hub, but i wanted to ask if this makes sense in my case before buying anything.


My previous Audio-Chain, which results in the green measurement, is:
Wall-Outlet -> PC -> USB -> Qudelix 5K DAC -> 3.5mm to 2x Clinch -> SVS SB1000 -> 2x Clinch to 2x Clinch -> 2x Swissonic A306
With 2 separate Outlets powering the Sub and Speakers to stop another ground loop issue.

A Ground Loop between the A306 and the PC seems to cause for the massive Hiss I get.
That's why i bought a IFI Defender+, which results in the orange measurement when audio is send via USB. When i don't playback anything I'm getting the red measurement (perfect other then the slight Hiss from the active speakers)


My current Audio-Chain (orange, red measurement) is:
Wall-Outlet -> PC -> USB -> IFI Defender+ -> Qudelix 5K DAC -> 3.5mm to 2x Clinch -> SVS SB1000 -> 2x Clinch to 2x Clinch -> 2x Swissonic A306
I tried all outlets available in my Room for the IFI Defender+, but they all have the same result.


All measurements are 5 averages of the Spectrum in the RTA section with my UMIK being ~15cm in front of the Right Speaker.
(1/48 smoothing applied afterwards , 32k FFT Length, Averages Forever stop at 5, Window Hann)

1727943915030.png


I'll try to provide additional needed Infos as soon as possible.

Thanks in Advance for the Help! :)
 
Last edited:
staticV3 said:
Try an actual USB isolator, instead of iFi's overpriced junk.

https://a.aliexpress.com/_opZRTJ5
https://aliexpress.com/item/1005001927948863.html
https://www.toppingaudio.com/product-item/hs01
https://hifimediy.com/product/hifime-high-speed-usb-isolator-v2/
https://hifimediy.com/product/usb-isolator/
Click to expand...
Thanks for the Links.

What do they do different to reduce the 1kHz noise as well as the broader noise caused by a ground Loop?
The IFI works great to reduce the Broad Noise (green vs orange/red measurement), so it seems to me like it might be a different problem but they might be worth a try once i understand how they work.
 
Plompudu said:
What do they do different to reduce the 1kHz noise as well as the broader noise caused by a ground Loop?
Click to expand...
The iDefender only protects against noisy USB VBUS.

Proper isolators protect against noise on VBUS (broad noise) and USB data lines (1kHz+harmonics).
 
Interesting, how does the protection of the Data Lines work?
How can i find a proper isolator on Amazon(DE) (below ~60€ if possible)? Do you have any links by chance?

Is it also possible to buy a cheap isolator (<20€) that only works for the Data lines (without a external power supply) that i can put in front of the IFI?
 
Plompudu said:
Interesting, how does the protection of the Data Lines work?
Click to expand...
Galvanic isolation via transformers:
ADuM3165-fbl (1).png

Plompudu said:
How can i find a proper isolator on Amazon(DE) (below ~60€ if possible)? Do you have any links by chance?
Click to expand...

Other isolators are available elsewhere.

Plompudu said:
Is it also possible to buy a cheap isolator (<20€) that only works for the Data lines (without a external power supply) that i can put in front of the IFI?
Click to expand...
There are cheap isolators <20€, but they don't support USB 2.0 speeds.
 
staticV3 said:
Galvanic isolation via transformers:
View attachment 396303



Other isolators are available elsewhere.


There are cheap isolators <20€, but they don't support USB 2.0 speeds.
Click to expand...
I'll read up on the Topic, thanks!

I'll buy the DSD one and will report back if it helped :)
How do you identify which are good/bad ones?
 
Plompudu said:
I'll read up on the Topic, thanks!

I'll buy the DSD one and will report back if it helped :)
How do you identify which are good/bad ones?
Click to expand...
Does the Qudelix power up without an external power supply, and with the internal battery disconnected?

And most importantly, do you get clean playback without spurious tones or wideband noise?

Then it's a good isolator.

Or did you mean before purchase?
 
The Q5K has a internal battery, but I like to use it connected since then i won't wear out the battery as quick.

What i meant was before purchasing it so that i know what to look out for when i ever need another one.
 
Plompudu said:
The Q5K has a internal battery, but I like to use it connected since then i won't wear out the battery as quick.

What i meant was before purchasing it so that i know what to look out for when i ever need another one.
Click to expand...
Many isolators will list the amount of current that they can supply to USB accessories.

You can use a USB Power Meter to measure how much current your Qudelix draws during playback, then double-check that the isolator in question can supply at least as much.
 
staticV3 said:
Many isolators will list the amount of current that they can supply to USB accessories.

You can use a USB Power Meter to measure how much current your Qudelix draws during playback, then double-check that the isolator in question can supply at least as much.
Click to expand...
Here is what i found online since I don't have a Power USB Meter.
Could you please check if you find anything that conflicts with buying this Item:
https://www.deshide.com/product-details.html?pid=619323

I couldn't find anything but i just want to make sure that i don't run too much into the Dac or Isolator when connecting it to the USB of my PC.

1727963807622.png

1727964179798.png

1727963859821.png
 
Plompudu said:
Here is what i found online since I don't have a Power USB Meter.
Could you please check if you find anything that conflicts with buying this Item:
https://www.deshide.com/product-details.html?pid=619323
https://www.amazon.de/-/en/gp/product/B0CSYNSZ3K/ref=ox_sc_act_title_3?smid=A1SUSVKN2N7NX6&th=1
Click to expand...
Neither do your images list the Qudelix's current draw during playback, nor does that specific isolator's product page list the maximum output current.

Plompudu said:
I couldn't find anything but i just want to make sure that i don't run too much into the Dac or Isolator when connecting it to the USB of my PC.
Click to expand...
You cannot "run too much" into anything.

The only possible issue is that your power supply may not be able to supply enough current, in which case the Qudelix may not work correctly, or not work at all.

If your power supply's current capabilities exceed what the Qudelix needs, then it will simply provide as much as the Qudelix needs and nothing more.

This is how all common power supplies work BTW.
Voltage is dictated by the source, current is dictated by the sink.
 
staticV3 said:
Galvanic isolation via transformers:
View attachment 396303

(...)

https://www.amazon.de/DSD-TECH-SH-G01L-USB-Isolator-High-Speed-Isolierung-480-Mbit-s/dp/B0CSYNSZ3K
Click to expand...
Thanks for the explanation, that makes sense after thinking about it for a bit.

The DSD Tech SH-G01L fixed all my issues.
Thanks a lot!

1728301357386.png



Now I've only got the background noise from my active speakers, which is totally fine with me since it's only at ~5-10phon at my nearfield listening position and only slightly audible.
100x average and peak compared to 0Phon, "10Phon" (0Phon+10dB) and 20Phon I'm getting the following background noise compared to speakers fully turned off:
1728302413994.png
 
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