Any solution to avoid PC interferance?

[Nobunaga]

Hey guys

After switching from my PCI-E soundcard into external usb powered DAC (Khadas Toneboard) and headphone amp, i am getting weird noises through my headphones.

I recorded them and uploaded it to youtube, i plugged my LAV mic in to my mobile phone and put it in to the headphone cuffs i also did it using just my mobile phone as mic.

Note that, this was recorded when i didn't have my Khadas Tone Board yet, i was using my soundcard as DAC. At first i thought the issue was simply the soundcard, but upon recieving the Khadas Tone Board i came to discover that it wasn't the case, the noise remained.

By now you might think that, it might be the amp. But it's isn't the amp either, when i plug the Khadas + AMP combo in to my laptop (battery powered - removing the psu) using the same USB and RCA cables it works perfectly, 0 noise. Same goes when i tested it with my mobile phone, plugged directly in to the amp also no noise.

There is one weird thing tho, that is worth mentioning, the first time i encountered this noise, the noise was different that the noise that i recorded. I made the recording a day later or so, and in the meantime i was using my Soundcard.

Also when i plug the DAC usb cable in the rear of my pc and not in the front, the noise gets much louder, aprox as loud as listening to music with the amp volume set to 40% and all other digital volume controls set to max.

Also after moving the amp and putting it somewhere else on my desk, the noise again got different, much louder and much more persistant.

At the very beginning after recieving the Tone Board, the noise sometimes would disappear, mostly re-appear when opening programs in windows or alt+tab to dektop, then the noise would disappear after 10 sec, and then after a few min reemerge.

When listening to music through Audirvana (program which bypasses windows upsampling etc) the noise wan't there. But when the noise got much louder and persistant, it wouldn't disappear in audirvana anymore.

Any suggestions what to do?

Maybe something like an Uptone USB regen or Intona USB 2.0 Hi-Speed Isolator could solve it?

Best regards

Yoshi

 

[DKT88]

10 yrs ago, I had the same intermittent noise on Windows 7 PCs with mechanical HDDs. I thought it sounded like the HDD head moving but that was only speculation. Around that time I switched to SSD and haven't heard that noise again. However this is just anecdotal.

 

[Blumlein 88]

Patient: Dr. it hurts when I do this.
Dr: Don't do that.

Or don't use that computer for audio.

If it did this with a PCI-e soundcard, then it isn't directly a USB problem. So would a USB isolation box help? I don't know. Could it be proximity, as in if you move the Tone board further away the effects are less or gone?

If you have a powered USB hub, even an old one, you could try it between USB plug and the Khadas Tone board to see if it helps.

The sounds are what you get with spinning HD's and mouse movements and interference from the monitor screen. Question is whether it all is getting into your gear via the USB plug or not I suppose.

It might help to know what amp you have and if it is plugged into the same outlet as your computer.

 

[Nobunaga]

I am just gonna make a list to answer it, so i don*t get lost in text

1. The amp is a Decware Taboo MKIII, it's not an original one tho, it is built with the original component list and drawings.

2. I never had any problems, with the PCI-E soundcard, the problems araised when using an external amplifier regardless if using external DAC or PCI-E as dac. This could mean that the RCA cables in proximity of the PC pick up the noise, because the only difference between external amp and allinone pci-e solutions are the rca cables (except circuitry and so on). In fact i was using el-cheapo RCA cables, the only ones i have, i have 2 different pairs but problem stayed the same.

However a small theory of mine is that the amp is more "transparent" and sensitive so it picks up and amplifies more subtle sounds/audio signal than the soundcard. Or the soundcard has an almost perfectly isolated analog section. They must have taken in to account the noisy enviroment of a PC when designing the soundcard and put measurements against it in place. Especially considering that Asus manufactures a lot of gaming hardware, and gaming rigs are much more powerful and noisier.

Which obviously the Khadas toneboard and/or the amp might not have payed so much attention to.

3. I need to use PC as audio, no other way.

4. I don't have a USB hub but i have these sort of hubs, more like extensions, didn't change anything.

5. I have 3 outlets in the bottom right corner of my room, the PC isn't plugged directly into the wall, but in to a hub where also other stuff like monitor etc is plugged in. I tried to plug the amp directly in to the wall, didn't change anything however i will try to plug it in a completly different outlet. I don't think that should matter all too much, because when i tested DAC+AMP with notebook, the amp was plugged in to the same outlet as before, in the same proximity to the PC as before, same with the DAC. I only moved the notebook didn't move anything else.

6. Proximity shouldn't be an issue either, after i moved the amp and the noise got worse, i unplugged everything and moved the amp+dac again where it was before it got worse, and it didn't get better. Also when testing the notebook the PC was running and like previously mentioned the amp+dac were in the same place, so it can't be the amp picking up room noise and neither the DAC.

7. It could also be a shared ground loop, most likely actually, there is an interesting video concerning this

. I remember that i had a similar problem once with my previous gen motherboard, at some point i started hearing buzzing noise using onboard audio. Because i thought that the motherboard was the problem i brought my PC to a local repair shop (where i bought the board). They said it was my power supply, they tried it with a different PSU, a much more powerful one (Corsair 1000Watt - platinum) and the noise was gone.
Then i ordered my own new Powersupply from Coolermaster, only gold rated but still very efficient and i would hear the same noise. That's why i bought the dedicated soundcard and solved the problem that way.

It could be that the PSU in the repair shop had a much better / different grounding and multiple rails, while both my PSU's were single rail (one current channel instead of multiple channels within the PSU), That makes me think that every single rail within the PSU has it's own seperate grounding, while single rail has only one grouning for all components. Just a theory tho.

 

[DKT88]

Or the soundcard has an almost perfectly isolated analog section. They must have taken in to account the noisy enviroment of a PC when designing the soundcard and put measurements against it in place. Especially considering that Asus manufactures a lot of gaming hardware, and gaming rigs are much more powerful and noisier.

I had exactly the same noise from several Asus sound cards which included the cheap models to the Essence STX. I got the noise right off the headphone output from the cards. Do you have a mechanical HDD?

 

[Nobunaga]

I had exactly the same noise from several Asus sound cards which included the cheap models to the Essence STX. I got the noise right off the headphone output from the cards. Do you have a mechanical HDD?

Yes, i have 2 mechanical HDD's, very old aswell, using one Samsung HD for 10 years or more now. But i need mechanical HDD's for storage, i have 4.5 TB of disk space with 2 mechanical HDD's and they are pretty much full.

I find it hard to believe that it's the mechanical hdds, the soundcard is positioned right infront of a 1080 GTX soundcard spinning at 75% fan speed and in front of the soundcard there are 2 more case fans.

What PSU do you have? Maybe your PSU is much noisier than mine.

Not getting any noise when using the headphone output of the card.

 

[bennetng]

May be relevant, may be not, I don't know.
https://blog.jdslabs.com/2018/11/jds-labs-atom-amp-official-release-benchmarks/#comment-22949
https://www.audiosciencereview.com/...audio-devices-discuss.5899/page-3#post-136615
http://archimago.blogspot.com/2013/02/measurement-asus-xonar-essence-one.html

 

[DKT88]

Yes, i have 2 mechanical HDD's, very old aswell, using one Samsung HD for 10 years or more now. But i need mechanical HDD's for storage, i have 4.5 TB of disk space with 2 mechanical HDD's and they are pretty much full.

I find it hard to believe that it's the mechanical hdds, the soundcard is positioned right infront of a 1080 GTX soundcard spinning at 75% fan speed and in front of the soundcard there are 2 more case fans.

What PSU do you have? Maybe your PSU is much noisier than mine.

Not getting any noise when using the headphone output of the card.

I had the problem 10 years ago. Haven't had the problem with recent computer builds which still use HDDs for storage. I play the music files from HDDs. You could try hooking up the DAC/amp with an optical cable and see what that does. Or shut down internal hardware on the computer like the GPU or fans for a test.

 

[March Audio]

I am just gonna make a list to answer it, so i don*t get lost in text

1. The amp is a Decware Taboo MKIII, it's not an original one tho, it is built with the original component list and drawings.

2. I never had any problems, with the PCI-E soundcard, the problems araised when using an external amplifier regardless if using external DAC or PCI-E as dac. This could mean that the RCA cables in proximity of the PC pick up the noise, because the only difference between external amp and allinone pci-e solutions are the rca cables (except circuitry and so on). In fact i was using el-cheapo RCA cables, the only ones i have, i have 2 different pairs but problem stayed the same.

However a small theory of mine is that the amp is more "transparent" and sensitive so it picks up and amplifies more subtle sounds/audio signal than the soundcard. Or the soundcard has an almost perfectly isolated analog section. They must have taken in to account the noisy enviroment of a PC when designing the soundcard and put measurements against it in place. Especially considering that Asus manufactures a lot of gaming hardware, and gaming rigs are much more powerful and noisier.

Which obviously the Khadas toneboard and/or the amp might not have payed so much attention to.

3. I need to use PC as audio, no other way.

4. I don't have a USB hub but i have these sort of hubs, more like extensions, didn't change anything.

5. I have 3 outlets in the bottom right corner of my room, the PC isn't plugged directly into the wall, but in to a hub where also other stuff like monitor etc is plugged in. I tried to plug the amp directly in to the wall, didn't change anything however i will try to plug it in a completly different outlet. I don't think that should matter all too much, because when i tested DAC+AMP with notebook, the amp was plugged in to the same outlet as before, in the same proximity to the PC as before, same with the DAC. I only moved the notebook didn't move anything else.

6. Proximity shouldn't be an issue either, after i moved the amp and the noise got worse, i unplugged everything and moved the amp+dac again where it was before it got worse, and it didn't get better. Also when testing the notebook the PC was running and like previously mentioned the amp+dac were in the same place, so it can't be the amp picking up room noise and neither the DAC.

7. It could also be a shared ground loop, most likely actually, there is an interesting video concerning this

. I remember that i had a similar problem once with my previous gen motherboard, at some point i started hearing buzzing noise using onboard audio. Because i thought that the motherboard was the problem i brought my PC to a local repair shop (where i bought the board). They said it was my power supply, they tried it with a different PSU, a much more powerful one (Corsair 1000Watt - platinum) and the noise was gone.
Then i ordered my own new Powersupply from Coolermaster, only gold rated but still very efficient and i would hear the same noise. That's why i bought the dedicated soundcard and solved the problem that way.

It could be that the PSU in the repair shop had a much better / different grounding and multiple rails, while both my PSU's were single rail (one current channel instead of multiple channels within the PSU), That makes me think that every single rail within the PSU has it's own seperate grounding, while single rail has only one grouning for all components. Just a theory tho.

Sounds like a simple ground loop. The folly of unbalanced rca connections I'm afraid.

Your amp probably has the RCA shell connected to mains earth and leakage currents are circulating from the PC.

Get an amp that's double insulated or a galvanic isolator such as the Intona.

 

[Blumlein 88]

Tube gear usually has much higher impedances in circuit. And this makes them more likely to pick up such stuff. You might alter the input impedance to something lower if it is a very high value. You might shield some parts of it. I've seen such things like this where putting a grounded piece of thick aluminum foil between tube and PC blocked lots of noise. Obviously not all computers are the problem as your laptop was okay.

 

[Nobunaga]

Tube gear usually has much higher impedances in circuit. And this makes them more likely to pick up such stuff. You might alter the input impedance to something lower if it is a very high value. You might shield some parts of it. I've seen such things like this where putting a grounded piece of thick aluminum foil between tube and PC blocked lots of noise. Obviously not all computers are the problem as your laptop was okay.

How to alter the impedance? It's transformer coupled

 

[Blumlein 88]

How to alter the impedance? It's transformer coupled

You can put a resistor across the input leads. If typical tube gear, it may have 100kohms or 200 kohms input impedance. You can solder across the input leads maybe 20 kohms which might help if that is the problem.

Again without knowing the circuit, this is maybe not optimum advice, but it won't damage anything.

And try some good shielded RCA connectors. You appear to have very cheap RCA interconnects. We aren't talking anything expensive. If you can put hands on some RGB video connectors that would do. Those are typically made from RG6 coax and well shielded.

https://www.amazon.com/Cmple-3-RCA-...8662&s=gateway&sprefix=RGB+rca,aps,227&sr=8-6

One example that uses RG59.

Or these:
https://www.amazon.com/Monoprice-10...d=1561358682&s=gateway&sr=8-3#customerReviews

 

[Nobunaga]

You can put a resistor across the input leads. If typical tube gear, it may have 100kohms or 200 kohms input impedance. You can solder across the input leads maybe 20 kohms which might help if that is the problem.

Again without knowing the circuit, this is maybe not optimum advice, but it won't damage anything.

And try some good shielded RCA connectors. You appear to have very cheap RCA interconnects. We aren't talking anything expensive. If you can put hands on some RGB video connectors that would do. Those are typically made from RG6 coax and well shielded.

https://www.amazon.com/Cmple-3-RCA-...8662&s=gateway&sprefix=RGB+rca,aps,227&sr=8-6

One example that uses RG59.

Or these:
https://www.amazon.com/Monoprice-10...d=1561358682&s=gateway&sr=8-3#customerReviews

And what if i would use SPDIF instead of USB wouldnt that solve problem?

 

[March Audio]

And what if i would use SPDIF instead of USB wouldnt that solve problem?

Quite likely, although you need to power the toneboard from a different USB supply (try just a phone charger) than the PC

 

[Nobunaga]

Sounds like a simple ground loop. The folly of unbalanced rca connections I'm afraid.

Your amp probably has the RCA shell connected to mains earth and leakage currents are circulating from the PC.

Get an amp that's double insulated or a galvanic isolator such as the Intona.

@March Audio

And are you sure an USB isolator would solve my problem? I just contacted Ciúnas Audio about their USB isolator (assuming it's an USB isolator like the Intona) and his answer was:

"No it won't solve your ground loop problem - I don't isolate the ground, I isolate the USB data lines themselves as this is how excellence in sound is achieved. You should solve the ground loop separately. Sorry, I can't be of much help but I have struggled with ground loop issues in Italy before & am afraid it was a nightmare"

I am not sure about what he means by that and if it would apply to all USB isolators.

What do you think?​

 

[pozz]

It sounds like intermittent EMI. Probably from the CPU.

I think March Audio is right about the solution. If youre interested in getting a balanced setup, proper AES/EBU ins/outs are transformer isolated.

 

[Nobunaga]

It sounds like intermittent EMI. Probably from the CPU.

I think March Audio is right about the solution. If youre interested in getting a balanced setup, proper AES/EBU ins/outs are transformer isolated.

I cant buy a new amp and a new balanced dac, impossible. My amp doesnt have balanced inputs only rcas.

I need to get rid of the noise

 

[pozz]

Quite likely, although you need to power the toneboard from a different USB supply (try just a phone charger) than the PC

Have you (@Nobunaga) tried this?

 

[Nobunaga]

Not yet, but not an ideal solution either considering that spdif adds jitter. I need to go and buy a SPDIF cable.

 

[KSTR]

Looks like a classic "ground loop" issue to me. The PC is earth-grounded which means USB gound is at earth potential, and your tube amp also is earthed which means audio ground is earth ground, therfore theses grounds are connected two-fold, one time via the RCA cable shield and one time via the protective earth connections. These earth grounds are not clean, notably the PC one. Thats why you have a circulating balancing current on the RCA shield which causes a voltage drop along it as it is not zero Ohms. That's where the noise comes from.
Intona USB isolator is the solution, or audio transformers after the DAC. USB isolation preferred.
EDIT: Or optical SPDIF aka TOSLINK