Recommendations for USB noise filtering product

[someAudioDude]

Without knowing the internals of the Questyle it's impossible to say exactly what's going on. The Khadas Tone Board has published schematics so I can use it as an example of the sort of thing that can happen - it can be powered by a separate 5V supply so doesn't necessarily need 5V as power from the USB. However it uses the 5V on the USB cable to flip the internal 'switch' that selects the USB input so, even though it isn't needed for power, the USB input won't operate without it. Questyle may be doing something similar.

Proper isolation devices comply with the USB standards, so should Just Work(tm) with any DAC - unless the DAC itself isn't actually compliant. The iDefender and various y-cables etc. break the standards in ways that often work, but sometimes don't. In the past this at least hasn't been damaging...usually...but with USB Power Delivery it can break devices and in extreme cases cause fires.

Hmm thanks for taking the time to elaborate. So, you're saying that using the idefender with an external 5v power supply isn't safe and can cause fire? Wow
Not sure what to do then i already bought the idefender. Shall I throw the questyle into the garbage

 

[mansr]

However it uses the 5V on the USB cable to flip the internal 'switch' that selects the USB input so, even though it isn't needed for power, the USB input won't operate without it.

This is actually a requirement in the USB spec.

 

[somebodyelse]

Hmm thanks for taking the time to elaborate. So, you're saying that using the idefender with an external 5v power supply isn't safe and can cause fire? Wow
Not sure what to do then i already bought the idefender. Shall I throw the questyle into the garbage

That's not quite what I'm saying. If you use a USB2 port on the PC and an ordinary 5V supply like the Raspberry Pi micro-USB one then there's no USB Power Delivery involved. It may or may not actually do what you want, but it shouldn't be damaging or dangerous.

USB Power Delivery arrived with one of the USB3 revisions (3.1?) and the USB C connector. Between them they're considerably more complex than USB2, and offer some exciting new failure modes if manufacturers get something wrong, even with something as 'simple' as a cable. Fire is a possible, if unlikely, outcome when people start creatively abusing the standard.

 

[someAudioDude]

I see, I've tried usb2 and usb3 ports and it works everywhere. Without the additional power supply it does nothing. Weird but then again it says "usb3" on the idefender so I guess and hope they knew what they were doing unlike questyle who made a killer device that sound exemplary well and musical but failed to "isolate"the usb or whatever. The same applies to MSI that is the manufacturer of the mainboard I'm using that failed to create a clean usb output (there is no issue at all when I use my mac notebook).

 

[zalan.reilly]

I'm having issues connecting my USB dac to my computer as I get random hissing and popping noises due to noise from my motherboard's USB.

I'm currently using a TOSLINK cable to connect to my DAC and the Nox Vidmate VLC issue seems to have disappeared but I'd rather use USB as I can play higher bitrate and sample rates as well as DSD through that which can sometimes be useful.

Unfortunately, my desktop has a mini-ITX board (never again) so I have no pci-e slots to put in an "audiophile grade" USB card so I'm not sure what product I would need to get rid of my issue.

iFi audio makes a lot of USB noise filtering products but what if I have a ground loop instead of a noise issue or vice versa? Not sure how to diagnose the problem I'm having.

Would be great if someone could put me on the right track thanks!

ATX is a large motherboard size. A pooder is slang for computer.

 

[MichaelP]

What happens when you disconnect all USB peripherals except the DAC?

 

[Mindcool]

So, the ifi idefender+ removes the noise entirely however, contrary to what they write on their website, I need to also connect the idefender to an external power supply. It's strange cause they say it's only necessary if your DAC is USB powered and the questyle is clearly not usb powered as it has a dedicated power supply. If I just plug it in there is no effect. This is confusing, I wish I could understand what the hell is happening on the physical level.

I needed to do the same thing to break a ground loop issue with my Topping E30.

 

[tar]

I don't believe it means your desktop is to blame. Based on your testing I believe your DAC is to blame. Break the ground ANYWHERE in the entire loop and your problem will disappear.

I guarantee if you purchased something like this:

https://www.amazon.com/Hosa-GLT-255-Female-Ground-Stopper/dp/B00FC4YPL4

It would also stop your problem. Does that mean it's your Monitors since this is where you implemented the fix? I would put the Hosa in before I would defeat the safety ground on your PC. I believe the Hosa keeps you safe.

It seems you are onto something here.

I have the same AMP/DAC Questyle CMA400i and am using the optical connection since 4 years(!) due to the interference on the speakers output when I use the USB connection.

After reading your post, I immediately tested the USB connection again and recognized that the issue only occurs on one monitor. I looked at the cables and remembered that I ordered 2 different lengths but of the same kind:
- Sommer Cable Galileo 238, 2.5 m
- Sommer Cable Galileo 238, 5.0 m

As you can see the connection is different, the 2.5m variant is metallic while the 5.0 m variant is isolated.

Guess what? The interference only occured on the monitor which is connected via the metallic variant. I then switched the cables between the monitors for verification by which the interference switched to the other monitor and I thought: "Oh, it is the metallic connection of the cable!" - Nope... after switching the cables on the CMA400i, it switched again to the other monitor.

That means, that one of the XLR connections of the CMA400i (here: the one to the right monitor) is somehow defect or incorrectly grounded.

Now, however, I am quite unversed in electrical engineering and am wondering whether it might not be a safety risk if I buy these HOSA plugs. Then there are so-called DI boxes (e.g. the ART Dual X Direct), which are actually used for balancing, but probably also dissolve ground loops (although I do not know here whether one should ground or lift). With those, there's also all the tangled cables and they can be quite expensive.

So right now I'm quite undecided whether I really want to test out these possibilities or just leave it at the optical connection with max. 96 kHz and no further stress.

 

[tar]

Another thing I just recognized: if you switch the output mode on the back of the CMA400i from "ADJ" to "FIX" the ground noise issue completely went away but the output level to the monitors becomes fixed and maximized(!) - balanced: 6.8 Vrms, unbalanced: 3.4 Vrms.

So, the USB issue is gone but you run into other issues:
- your monitors volume is not adjustable via the volume knob of the CMA400i anymore (but your headphones volume still is)
- your monitors are activating and deactivating themselves whenever an audiosignal starts/ends with a slight "plop" (they are not really switched on/off but you recognize that some circuits are activated/disabled)

If you have another hardware volume control (e.g. directly on your monitors) and are not often starting/ending any audio media that may be not much of an issue but otherwise you would need to take some measurments to be able to adjust the monitors volume (even in ASIO mode) within Windows (e.g. via Volume²) and to prevent constantly overdriving your monitors (e.g. by setting a negative PreAmp via Equalizer APO). Unfortunately, I have no idea how to solve the plopping and I guess, this is due to the high voltage output which could only be solved via another hardware PreAmp between the CMA400i and your monitors.

In my opinion, the fixed mode and ASIO (and WASAPI Exclusive and WDM-KS) makes things much worse in the everyday PC routine as you usually switch between different media files (the plopping is really annoying) and listen to multiple outputs simultaneously (a video in your browser, a song in the background, MS Teams, getting notifications etc.). Furthermore, most of the media files one consumes are within the 44.1/48 kHz range which would result in a constant upsampling to 48+ kHz when using anything above 48 kHz.

Thereby I conclude that on the PC the usage of the "ADJ" mode with an optical input and a sample rate of 48 kHz would be sufficient for 95+ % of the time. By that, the CMA400i is a bit of a overkill for PC.