Solved! Mains conditioner to fix humming from PC audio

Desolator69

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Oct 23, 2014
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Hey hey everyone,

So about a year ago I bought an M-Audio AV32.1 speaker system to replace my Trust Tytan 2.1 system. They sounded much nicer however I returned them due to ground loop humming that wouldn't go away. It wasn't too loud but it was still very noticeable and annoyed the heck out of me.

My signal chain was: PC -> Behringer UMC22 audio interface (1/4" TRS output on the back) -> M-Audio AV32.1.

I placed a Behringer HD400 isolator between my UMC22 audio interface 1/4" TRS output and the M-Audio system input. The hum was still there so it wasn't hum from my PC USB. I plugged the AV32.1 into the back of my PC (direct into the speaker out port) and it still hummed. I'm pretty certain the hum came from the mains power going to the speaker since it has a metal ground pin (unlike my Trust Tytan 2.1 system which has no ground pin).

TL;DR, My question is this: would a mains power conditioner help remove this kind of hum? Such as this unit here:

https://www.amazon.co.uk/gp/product/B00UB0G4DQ/ref=ox_sc_act_title_1?smid=A3P5ROKL5A1OLE&psc=1

It has great reviews but I'm wary about spending just under £35 on a thing that may not work. If it works I may get one and give the speakers another try.

Thanks for any feedback :)
 

milktea

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Dec 16, 2009
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Your PC sound card shouldn't be that bad, even though it's not a high quality audio device. There shouldn't be any hums, even when your PC is plugged-in directly to the wall. Sounds like you have quite a bit of experiments to run to find out the source of the problem. Start with the most basic setup, PC and headphone and no surge protect. And move the PC/headphone setup to different locations in your house. Piece by piece add more components to your setup until the hum comes back.

Also, try checking the connectivity of electrical outlets, such as the 3-Wire Receptacle Tester.

I would also suggest bring your setup to another house to double check if any issues.

Also, it would help if you have a known good setup, such as borrow from another that is known to be hum-free.
 

justin.m.beauvais

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Dec 15, 2017
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That most likely do the trick, but before that you should try something a bit cheaper to see if it works. Magnetic EMI line filters might be just what you are looking for. They are basically magnets that either clip onto the power cable or that you wrap the cables around. They work surprisingly well and are a cheap test, $10-ish. I've used them for both my PC power input and for TVs. They are pretty darn good at removing interference caused by dirty power.

I have a feeling that they should at least minimize the noise, if not remove it completely, for your setup. They sell them in packs as well, so you could filter both your audio and input power.

Best of luck to you.
 

Desolator69

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Oct 23, 2014
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Hmm, thanks for the suggestion. I forgot about those clip-on ferrite cores. I'll give them a go first, if it helps then great! May be a short while before I buy the speakers again though.
 

Desolator69

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Oct 23, 2014
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They were all connected to the same 4 socket, surge protected power adapter/extension.




I don't remember the HD400 affecting hum at all, pretty sure it was still there and wasn't reduced. And the hum was still there even when connecting the speakers with an RCA to 3.5mm jack to the PC's rear port (the green one normally used for speakers).
 

milktea

Distinguished
Dec 16, 2009
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Your PC sound card shouldn't be that bad, even though it's not a high quality audio device. There shouldn't be any hums, even when your PC is plugged-in directly to the wall. Sounds like you have quite a bit of experiments to run to find out the source of the problem. Start with the most basic setup, PC and headphone and no surge protect. And move the PC/headphone setup to different locations in your house. Piece by piece add more components to your setup until the hum comes back.

Also, try checking the connectivity of electrical outlets, such as the 3-Wire Receptacle Tester.

I would also suggest bring your setup to another house to double check if any issues.

Also, it would help if you have a known good setup, such as borrow from another that is known to be hum-free.
 

Desolator69

Estimable
Oct 23, 2014
12
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4,560
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Oh man, I mean I can I can remove all other devices from the plug and reinstall one by one, but I can't move my setup really, it's a full-size desktop PC and monitor on a desk-clamp stand. Once I get back home next week I'll do as good a check as I can do in terms of where it's plugged in currently. It's a good idea so it's worth a shot :)
 
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