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Answered How to eliminate PC static noise?

bandyka

Well-known Member
Hello All,

I am having a rather annoying problem with static noise through headphones. Please see my signature for setup. The PC supposed to be some of the best money can buy running i7 6700K 16GB RAM Gygabyte mobo and a brand new 750 watt Corsair bronze PSU.

I've just picked up a rather high end Stax SRS-3170 electrostatic headphones which comes with its own amp, all is well except I am hearing huge amounts of static coming from the PC. The headphone amp is connected via analogue high quality cables which are hooked up to my main Onkyo receiver via Zone 2 pre out.

The noise is like having an ancient dial up modem squeaking in my ears constantly and the tone and intensity changes depending on what I do on the PC, it seems to be the worst when browsing the web and have a white background displayed.

I am going away for a couple of days so apologies for not replying but hoping I'll have some good suggestions here by the time I get back as its rather annoying having top of the line equipment and having such a problem.

Thanks
 

bandyka

Well-known Member
Forgot to say the audio is hooked up to the receiver via HDMI bitstream from the video card GTX 970. When the PC is off no noise so its not the amp, cables or the receiver.
 

alphaomega16

Distinguished Member
Can you not hook the headphones into the PC by any other means whilst its connected via HDMI such as the output on the motherboard and see if it still does it ?

Do you have another set of headphones you can try ?
 

bandyka

Well-known Member
Its definitely the PC as when the PC is off there is no noise and when I switch to other sources also fine.
 

bandyka

Well-known Member
..and no cannot hook them up via other means unfortunately but its confirmed the PC is the issue.
 

Stuartj1

Active Member
What kind of noise are you hearing. Is it complete white noise or a particular pulse?
 

bandyka

Well-known Member
"The noise is like having an ancient dial up modem squeaking in my ears constantly and the tone and intensity changes depending on what I do on the PC, it seems to be the worst when browsing the web and have a white background displayed."
 

bandyka

Well-known Member
OK so on more critical listening I was able to make out that its most likely the PSU leaking through. When I turn on the PC and is running idle its coming through as fan humming in a digital form and when doing something else it changes to a a coil whine type but comes through distorted as a sort of dial up noise.

I am quite certain now its the PSU leaking into the system.
The question is would a 1st class Gold/platinum PSU do the trick or are there other ways to reduce/eliminate this leakage?

Keep in mind it only comes through the headphones as they are extremely high output and are capable of playing back every and any detail in the source which is why I suspect they pick up this noise. I used to hear the same on speakers on lower end PCs too.
 

Stuartj1

Active Member
It could be a peripheral connected to the PSU. If you can try a disconnect none essential hardware one at a time and monitor the noise.

Otherwise same as Chuck Norris said.
 

steveo67

Active Member
Does the noise stay there when you output via your speakers?
If not then the coupling is likley taking place between your receiver and headphone amp. Are you using well screened cable to do this? There's a lot of opportunity for EMI from the PC in general to end up on low level, low impedance analogue inputs.
Try disconnecting the wire at the amp but dont move it too much and see if it still remains. Also try doing it with just one wire and check for the same.
 
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GMC79

Distinguished Member
Given the rest of your system being high end and that they are £1200 headphones if it were me id have a quality external USB DAC feeding the amp part of the headphones directly with analogue phono. Could also feed Onkyo amp at same time via optical.

Arcam irDAC, Meridian Director etc.


could get a cheaper one to test like a CYP AUD 3 but id be confident it'd fix the problem, Surprised if it didn't tbh. them electrostatic headphones must be too sensitive.
 

bandyka

Well-known Member
Given the rest of your system being high end and that they are £1200 headphones if it were me id have a quality external USB DAC feeding the amp part of the headphones directly with analogue phono. Could also feed Onkyo amp at same time via optical.

Arcam irDAC, Meridian Director etc.


could get a cheaper one to test like a CYP AUD 3 but id be confident it'd fix the problem, Surprised if it didn't tbh. them electrostatic headphones must be too sensitive.

Well the problem is I feed direct bitstream which needs to go through via HDMi so not sure how I could go about this?
 

bandyka

Well-known Member
Does the noise stay there when you output via your speakers?
If not then the coupling is likley taking place between your receiver and headphone amp. Are you using well screened cable to do this? There's a lot of opportunity for EMI from the PC in general to end up on low level, low impedance analogue inputs.
Try disconnecting the wire at the amp but dont move it too much and see if it still remains. Also try doing it with just one wire and check for the same.

I can barely hear it via the main speakers but its there however not noticeable the headphone amp seems to amplify it big time. The cables are some of the best I could find. When I switch to another source on the amp the noise goes away and when I disconnect the cables too.
 

bandyka

Well-known Member
turn up the volume

Actually this is a part solution as if I turn up the volume high on the main amp it gets better as it only starts makingasking the noise at about 20-25% volume on the headphone amp but its still not good enough.
 

bandyka

Well-known Member
probably the bronze psu, swap for a platinum or gold, see if that solves it.

We don't know if this is the solution yet but it well could be.
 

steveo67

Active Member
The signals pretty much in the digital domain until it's converted in the receiver so the opportunity to pick up the PC noise is minimal aside from the analogue stage. I'm pretty sure the amp will be well designed on an EMC/EMI front but it doesn't rule out a bad section slipping through testing. Having said that my gut feel is that this is pick up in you cable and headphone amp.
Can you drive anything else from the pre-amp outputs to see if it is still present?
It's also worth trying to move the headphone amp further away from the PC to help determine if its radiated noise or conducted. Also rotating the cable run to other orientations to see if it changes is useful info.
Silly question perhaps but does the pre-amp out have a volume control? If that's very low and your headphone amp is set high you'll get this effect. Obviously turn the headphone amp down before you fiddle with this!
 

steveo67

Active Member
OK - Given your recent reply on the volume then that's probably the issue. Adjusting the Zone 2 volume raises the input signal up above the noise floor. Assuming you have this output at a reasonable level and the headphone amp not too far up the dial, the next likely factor stopping you getting good signal to noise ratio is probably an impedance mismatch. It's worth checking the Onkyo drive to the pre-amp out - It's likely to be nominally 1V into 470 Ohms but worth checking it is. Then compare that to the headphone amp which will be probably be looking for around that voltage range into, typically a much higher input impedance. These need to be compatible otherwise you get too quiet/noisy or too loud/distorted.
If they are miles out you may be looking at getting a cable to try driving from the headphone outputs which should have a bit more headroom.
 

bandyka

Well-known Member
Steve I think you are onto something.
Also one thing worth noting is that during testing I found that I cannot crank Zone 2 volume up above 75 as it will start getting into serious distortion and weirdly if the main output sound mode selected on the onkyo is Dolby Surround I get some hugely distorted faint sound leaking via the front left Atmos speaker this only happens past Zone 2 volume level 75. Another things worth mentioning is that the headphone also gets the noise if Zone 2 is disabled but as soon as I change source (anything other than PC) the noise dies so it also raises questions about the Onkyo's source isolation.
What do you exactly mean by? "If they are miles out you may be looking at getting a cable to try driving from the headphone outputs which should have a bit more headroom." To get a converter?

This is what I found in the specs for the Onkyo:

Rated RCA Output Level and Impedance 200 mV/470 Ω (Pre Out) Maximum RCA Output Level and Impedance 4.6 V/470 Ω (Pre Out)

...and for hte Stax amp: STAX SRS-3170
 

steveo67

Active Member
OK - Sounds like the Zone 2 output can go between 200mV and 4.6V. A quick look at the spec of the headphone amp suggest it's looking for 100mV in, possibly up to 100V but that seems odd (not the best spec sheet I've seen!).
What might be worth a try is connecting to the L/R preamp outputs which should be fixed (or at least controlled off a different circuit) but at around the same nominal level. Try driving the headphone amp with those and see what comes out. If that's fine then Zone 2 on amp has issues.
The bit earlier about the headphones was just a test mode to feed something with more level. It's slightly dodgy and you need to be careful with the volume to avoid overloading the input but I'd park that in favour of the above (safer) test. It was really just a quick test before suggesting an impedance matching device.
 
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bandyka

Well-known Member
So should I use the Pre/Out front left and right speakers output?
 

bandyka

Well-known Member
OK tested zone 3 and main pre out not a sound coming through at all. ( I mean no content whatsoever)
 

steveo67

Active Member
So should I use the Pre/Out front left and right speakers output?
Use the Pre-out Front phono sockets (not speaker terminals) - that would be bad.
 

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