Ground loop elimination and PC usb noise

[Lavawood]

Try this before you go for anything more expensive
I asked the same question recently and this was the advice I got:

https://www.ebay.com/itm/1500V-USB-...lation-ADUM4160-ADUM3160-Module-/201771509748

 

[olinko]

Try this before you go for anything more expensive
I asked the same question recently and this was the advice I got:

https://www.ebay.com/itm/1500V-USB-...lation-ADUM4160-ADUM3160-Module-/201771509748

I've seen those and they're an option too, but someone in another thread that "everything but" the ifi iDefender also limits the frequency (it think it was down to 48 kHz) so I first wanna try with the ferrites I already have at home

 

[solderdude]

sorry to jump in, but I didn't wanna make a new thread on what seems to be a recurring topic.
I'm waiting for my SMSL M300 MkII + SP200 stack to arrive and I'm pretty sure I'm going to have USB ground loop issues (pretty unavoidable dirty power at my place). I intend to connect the M300 balanced with XLR to the SP200
Now, I'm used to TOSLINK optical and actually prefer it, but in this case I don't wanna limit any of the DAC's capabilities (like DSD playback for example).

Now I know they're not THAT effective, but what's the best way to place ferrites on the USB cable? Should I put one on both ends? Put ferrites all over the cable in the hopes that it'd be more effective? (I'm gonna have five ferrites available)

Ferrites only help with HF common mode nasties, they do nothing when it is in the audible range.
When you have clamp-on ferrites (the ones that open up) or ring ferrites you can get the most out of them (if possible) by making 3 to 5 windings around it.
More does not help much.

Different ferrite types exist that are effective in different freq. ranges.

The only way to cure a ground loop in the audible range is to break it with a balanced connection or a audio transformer or optical connection or USB cleaner. (not all are equally effective/easy to use)

 

[olinko]

Ferrites only help with HF common mode nasties, they do nothing when it is in the audible range.
When you have clamp-on ferrites (the ones that open up) or ring ferrites you can get the most out of them (if possible) by making 3 to 5 windings around it.
More does not help much.

Different ferrite types exist that are effective in different freq. ranges.

The only way to cure a ground loop in the audible range is to break it with a balanced connection or a audio transformer or optical connection or USB cleaner. (not all are equally effective/easy to use)

Do you know of any USB isolator/cleaner that wouldn't limit the signal in any way?

 

[solderdude]

There are quite a few that can do upto 480 Mb but they are expensive.

I suggest to wait with any purchases till the gear comes in and you used it.
All gear should work properly even with 'dirty mains'.
Only when you are experiencing problems or are hearing sounds that should not be there I would look into a remedy.
Not all equipment has (audible) common mode issues.

 

[Veri]

Do you know of any USB isolator/cleaner that wouldn't limit the signal in any way?

The Intona is basically just an USB hub, the device itself sees only the computer, not the isolator. No effect on PC-Device interaction.
But like solderdude says. expensive. got mine used for under 150eur. still a lot of money.

 

[olinko]

I guess I'll have to cross my fingers, there's still a chance I won't get any noise, right?
The SMSL stack hasn't arrived yet, I'm just preparing for potential problems

 

[madugo]

So I got the same problem with usb noise from my PC to topping E30 dac, and my PC don't have any optical outputs.

What's the best solution for me?

I am actually going to upgrade the Dac to a balance dac, such as the new Su-9, to feed to my balanced amp.

Does balanced dac reduce/cure the noise issue?

Thanks.

 

[dachiznitt]

So I got the same problem with usb noise from my PC to topping E30 dac, and my PC don't have any optical outputs.

What's the best solution for me?

I am actually going to upgrade the Dac to a balance dac, such as the new Su-9, to feed to my balanced amp.

Does balanced dac reduce/cure the noise issue?

Thanks.

I had the same problem. Put electrical tape over the ground pin on the usb plug. Problem solved and now silent. No noise.

 

[madugo]

I had the same problem. Put electrical tape over the ground pin on the usb plug. Problem solved and now silent. No noise.

Just tried that, it took some of the noise away, but added a higher pitched hump...

 

[wwenze]

I had the same problem. Put electrical tape over the ground pin on the usb plug. Problem solved and now silent. No noise.

I should warn that even though USB uses differential signaling, the ground pin is still needed so the common mode voltage does not float too far away until both pins of the differential pair are seen as both high or both low. This may be an issue with some class II appliances, you know, those that measure 50V when you poke the chassis with a multimeter.

 

[wwenze]

So I got the same problem with usb noise from my PC to topping E30 dac, and my PC don't have any optical outputs.

What's the best solution for me?

I am actually going to upgrade the Dac to a balance dac, such as the new Su-9, to feed to my balanced amp.

Does balanced dac reduce/cure the noise issue?

Thanks.

From where does the noise start? If you use headphones with the E30 without connecting the E30 to another amp, do you hear the noise?

 

[madugo]

From where does the noise start? If you use headphones with the E30 without connecting the E30 to another amp, do you hear the noise?

The noise is from the PC I guess.

I tried disconnected the usb from the PC, and use my cd player as source, feeding with optical to the E30 dac, and same way connecting to the same amp, the noise is gone.

But also this is a new tube amp, I did not have any problem while using E30, feeding with USB from PC to my THX 887, it's dead silence.

So not sure what's the deal, maybe the tube amp is more sensitive to noise?

I guess the next thing for me maybe either try with a balanced dac with XLR or buy a sound far with optical output for the PC?

 

[solderdude]

I assume the PC is not properly grounded (plugged into a 2 prong mains outlet ?

Most likely a USB isolator may be the easiest solution.

 

[madugo]

I assume the PC is not properly grounded (plugged into a 2 prong mains outlet ?

Most likely a USB isolator may be the easiest solution.

My house have all three prong outlets.

What would be a recommendation on usb isolator? some say they are snake oils?

 

[solderdude]

When you have a groundloop from the PC they are anything but snake oil.
Do note that a reclocker or USB+ injectors are NOT galvanic separators/isolators even though some claim to be.
Also note that most have a limited bandwidth.

 

[AnalogSteph]

But also this is a new tube amp, I did not have any problem while using E30, feeding with USB from PC to my THX 887, it's dead silence.

So not sure what's the deal, maybe the tube amp is more sensitive to noise?

There was a guy with a Woo Audio something or other (WA2SE?) here recently with much the same problem. Let me guess - amplifier is IEC Class I as the case for most tube gear, audio ground is referred to mains protective earth, and no input transformer that could provide galvanic isolation. Let's just say the designers of these things aren't always the most competent, or at least didn't envision use with anything but floating hi-fi sources. If you connect a PC (another Class I device), it's instant ground loop time.

So galvanic isolation time it is. Either via USB, or a line-level isolator, the quality of which can be quite variable (though a tube amp may not be all that critical in this regard, they often have plenty of distortion themselves).

 

[madugo]

When you have a groundloop from the PC they are anything but snake oil.
Do note that a reclocker or USB+ injectors are NOT galvanic separators/isolators even though some claim to be.
Also note that most have a limited bandwidth.

Thank you for the comment, is there any product that you recommend? Don't want to buy something ended up not really working.

 

[madugo]

There was a guy with a Woo Audio something or other (WA2SE?) here recently with much the same problem. Let me guess - amplifier is IEC Class I as the case for most tube gear, audio ground is referred to mains protective earth, and no input transformer that could provide galvanic isolation. Let's just say the designers of these things aren't always the most competent, or at least didn't envision use with anything but floating hi-fi sources. If you connect a PC (another Class I device), it's instant ground loop time.

So galvanic isolation time it is. Either via USB, or a line-level isolator, the quality of which can be quite variable (though a tube amp may not be all that critical in this regard, they often have plenty of distortion themselves).

Any product to recommend?

Also if optical output is suppose to end the problem, what's the reason not for me to buy a sound card with optical output? it's not that expensive I suppose.

 

[Rantenti]

I assume the PC is not properly grounded (plugged into a 2 prong mains outlet ?

Most likely a USB isolator may be the easiest solution.

Can I still get a ground loop if my USB cable from PC to DAC is data only and no power goes through the USB cable? I suppose the data wires are still "electrically conductive" could still contribute to a ground loop, is this correct?