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Power supply whine

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Power supply whine

Postby yaire » Mon Jul 08, 2019 12:16 pm

Hello people,

I have an older DIY PC with a BeQuiet power supply (I believe 850 W).
It is about 10 years old.

I love using my P90 equipped guitar and this picks up a lot of whine from the power supply. I deduced that from moving the pickup around the PC with the lid off, all other components seem quiet.

Also everything that is connected via USB to audio gives a lot of whine (electribe sampler, Behringer Neutron, Yamaha DTX-450). This is the same whiney noise.
Removing the USB connection makes everything dead quiet. (connected to a RME babyface or Behringer ADA8200 via optical ADAT to the babyface).

The whole rig is chained to one wall socket without ground (Netherlands).

Would it make sense to look out for a new power supply?

I read that Seasonic powersupplies are pretty susceptible to whine and Corsair has a marketing blurb about having power supplies that hardly whine.
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Re: Power supply whine

Postby Hugh Robjohns » Mon Jul 08, 2019 12:37 pm

I was going to say that your description of the whine going away when you disconnect the USB cable is pretty classic of a ground loop... but it appears you have no ground via the mains so it can't be a traditional ground loop.

However, very similar problems with unwanted ground noise can occur precisely because the system lacks a solid ground. So before swapping out power supplies in the computer, I think the first thing I'd try is actually providing a solid reference ground to the PC, just to see if that helps.

Not only is that likely to minimise the whine heard via your external hardware, it may also improve the shielding of the PC itself which may well reduce the radiated interference being picked up by your guitar.

If you don't have a ground terminal at the wall socket, you may be able to find a solid ground from a water pipe or similar... I don't know the arrangements in the Netherlands, but a local electrician should be able to help.

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Re: Power supply whine

Postby Pete Kaine » Mon Jul 08, 2019 5:09 pm

yaire wrote:I read that Seasonic power supplies are pretty susceptible to whine and Corsair has a marketing blurb about having power supplies that hardly whine.

Hugh's already said the important stuff above.

I'm just going to mention that Corsair is largely a marketing company who farm our their hardware construction, so you can take that with a pinch of sodium. Seasonic makes the best PSU's they have in the Corsair range (AX series) for them, so I don't see how the budget models would fare any better.

When I was still doing system support, the Corsair was normally very reliable as far as life expectancy goes, but the number of cheaper models we had coming back for coil whine was certainly higher ratio wise than budget Bequiet or Seasonic.
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Re: Power supply whine

Postby yaire » Tue Jul 09, 2019 8:52 pm

Thank you Hugh and Pete for your replies.

I connected my rig to an outlet in the kitchen which does have ground.
And I have hardly any whiney noise.

And then I reconnected to my standard non-ground socket and I still have hardly any noise :roll:

Is there any way that connecting the ground discharged some load to ground which results in the disappearance of the whine? Seems very unlikely to me.

So basically there is no problem now...



A few other observations I made:

With the ground connected in the kitchen I do have some of the whine noise over my guitar speaker when turning the clean channel fully up, but this is not a level I generally use it on. And it seems a lot less than that it generally was.

When recording the guitar noise via DI on my H&K tubemeister 18 the noise floor is nice and even over all frequencies when recorded and no whiney spike on a spectrum analyser (with and without ground).

So I do get a little whine over the speaker (unbalanced) but not over DI (balanced).

without ground:
There already was no problem with balanced connections.
There was also no problem when I connect any of the unbalanced audio sources via MIDI (and no usb connection).

The noise occurred with No MIDI connection but with usb connection.

Are MIDI connections always isolated in some way? I use the RME babyface MIDI and a midisport 2x2.
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Re: Power supply whine

Postby Hugh Robjohns » Tue Jul 09, 2019 9:17 pm

Yes, MIDI uses onto-couplers, so,there is no direct connection and thus no possibility of ground-loop noise.

It is encouraging that the system became whine-free when powered from a grounded socket, but I'm as confused as you over why it remains noise-free when powered from an ungrounded socket.

Something to keep an eye (ear) on...

Did you just move the mains cable, or did your test involve disconnecting, moving and reconnecting the whole system?
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Re: Power supply whine

Postby hobbyist » Tue Jul 09, 2019 10:20 pm

yaire wrote:Hello people,

I have an older DIY PC with a BeQuiet power supply (I believe 850 W).
It is about 10 years old.

I love using my P90 equipped guitar and this picks up a lot of whine from the power supply. I deduced that from moving the pickup around the PC with the lid off, all other components seem quiet.

Also everything that is connected via USB to audio gives a lot of whine (electribe sampler, Behringer Neutron, Yamaha DTX-450). This is the same whiney noise.
Removing the USB connection makes everything dead quiet. (connected to a RME babyface or Behringer ADA8200 via optical ADAT to the babyface).

The whole rig is chained to one wall socket without ground (Netherlands).

Would it make sense to look out for a new power supply?

I read that Seasonic powersupplies are pretty susceptible to whine and Corsair has a marketing blurb about having power supplies that hardly whine.


I have heard lots of power supplies whine. Typically it is loose windings in a coil. If yours is intermittent it may be due to heat and when it is cool it stops.

Try leaving it on for a while and see if the whine comes back.

I hated those IBM 2260s and 3270s. The whine drove my ears crazy. Other people claimed they could not hear it.
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Re: Power supply whine

Postby yaire » Fri Jul 12, 2019 12:34 pm

Thanks hobbyist,

I did some more experiments.
Had the PC on for an hour. Whine was very present.
Left th PC of for 10 minutes (longer than I did before).
Switched on and same whine was there. So I can not reproduce the quieting of whine due to temperature difference.

Connected to grounded socket in the kitchen.
Whine was less but still present.

Reconnected to normal ungrounded socket.
Whine was very present again (where last time it was quiet for a while but returned after some time).

So conclusion for me:
Use grounded socket (will be doing that next year, in the room where my music stuff is going to be).

Not convinced that swapping out power supplies will be a good investment at this moment. It would not guarantee a whine free life.
If I would swap it then the 'be quiet! Dark Power Pro 11 1000W' would be on my radar.

Thank you all for thinking with me.
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Re: Power supply whine

Postby Hugh Robjohns » Fri Jul 12, 2019 1:05 pm

I'm assuming the whine is heard via the speakers, rather than an acoustic noise from the PC power supply...

But from your update, it looks like the lack of a ground is a factor in the noise problem.

The fact that the whine is reduced is obviously good... but the reason it doesn't go completely could well be down to ground-loops in your newly grounded system. So the next stage would be to work through the rest of your system, item by item, to see if one of those external units is creating a loop... and if it is we can work out a way to break it.

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Re: Power supply whine

Postby yaire » Sat Jul 20, 2019 6:59 pm

Hi Hugh,
The whine is heard through the speakers and not from the power supply itself. Correct.

My biggest issue is the whine through the guitar. Where the whine is caught through the EM field. It does change with orientation and distance of the guitar to the PC/ power supply.
This is the major concern I want to fix.

Then:
All equipment with:
a: wall warts (so no ground pin)
b: unbalanced connections
whine through the audio interface / speakers when USB is attached
(no problem when no USB is attached)

A little test with my electronic drums (Yamaha DTX450k) with a USB connection
Noise occurs when I playback the drums through:
a RME Babyface (connected to the PC)
b ADA 8200 (optical to babyface, shares grounded socket with PC)
c mixer(XENYX 502, wallwart, no ground pin, with KRK V4 monitors ( shares grounded socket with PC)

BUT;
Most of the noise is gone when sending the drums audio to:
mixer(XENYX 502, wallwart, headphones (monitors disconnected)
When I plug in a monitor (in one of the mixer's outputs) then the noise returns.

So in this case the KRK monitors, connected to the mixer create the ground loop to the PC.
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Re: Power supply whine

Postby Hugh Robjohns » Sat Jul 20, 2019 7:14 pm

yaire wrote:So in this case the KRK monitors, connected to the mixer create the ground loop to the PC.

This is quite common, sadly. The solution is to break the ground connection in the audio cables feeding the monitors. If you're handy with a pair of cutters and some insulating tape, the snip the cable screens inside the plugs at the speaker end (pin 1 if XLR, or the sleeve on TRS) and insulate.

Alternatively, invest in a transformer isolator box like the ART DTI which electrically isolates the input connections from the output connections, while passing the signal magnetically through the transformer.
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