Speakers buzz when touching the audio plug. Solution?

[Mugsy]

I upgraded my friend's PC. Everything was just fine before, but when I went to put everything back, his speakers (2.1 config) now make a loud buzzing noise if ANYTHING touches the audio jack/plug... my finger, the computer... doesn't matter. The computer doesn't even have to be on. Simply touching the plug creates a loud "ground loop" hum. The hum does not go away after the computer starts (and continues to buzz when the computer is off.)

We tried replacing the audio cable but it made no difference. Ditto for plugging the speakers into another wall outlet.

It didn't do this before. And it clearly isn't a computer problem. But I'm getting "the look" regardless.

Does anyone know how to fix this? TIA

 

[DelJo63]

The outer cover of the audio connector is not grounded and the "ground loop" is the result.
You might try reversing the connections on the inside of the case.

 

[Mugsy]

The outer cover of the audio connector is not grounded and the "ground loop" is the result.
You might try reversing the connections on the inside of the case.

Thanks for the reply. I'm not clear on what I should do here.

The cable is a standard PC Audio cord with 3.5mm din on each end (Green plug.) The cable plugs into the subwoofer. The other end causes the "ground loop buzz" simply by touching the other plug (no computer needed.)

So the only "case" to open would be the subwoofer. And I'm not sure what I would "reverse" inside of it.

 

[Cycloid Torus]

I'm not as sharp as jobeard, but I think you might want to look carefully at the motherboard to jack connection. I had a similar problem when I failed to properly ground a jack where the snap-in shroud thingy failed to touch (and ground) inside the case.

 

[Mugsy]

I'm not as sharp as jobeard, but I think you might want to look carefully at the motherboard to jack connection. I had a similar problem when I failed to properly ground a jack where the snap-in shroud thingy failed to touch (and ground) inside the case.

Thx for the follow-up. But like I said, the speaker buzzes when I simply touch the speaker plug with my hand, so the problem isn't inside the computer.

It's unquestionably a "Ground Loop" causing the buzz, but the usual fixes of plugging the speakers into another outlet, turning off every other electrical device in the room or replacing the audio cable didn't help.

 

[Cycloid Torus]

Could it be an unshielded magnetic field near loops of wire?

 

[Mugsy]

Could it be an unshielded magnetic field near loops of wire?

I'm not sure. I told my friend to try moving the speakers to another room and plugging them in there to see if the problem goes away. Either he didn't try it yet, or he tried and it didn't work. Either way, he never called back with "good news".

I'm going back over there this morning. We'll find out. Thx.

 

[DelJo63]

The MB connection to the Audio Plug is in question.

The cable outer connection should be making a contact with the MB ground. If this is reversed (inside the PC case) then touching the cable makes a connection to the Audio In or Out as is appropriate.

The order of suspects is:

1. the cable is suspect -- replace it
2. the wiring within the PC case is not correct.

 

[learninmypc]

Thx for the follow-up. But like I said, the speaker buzzes when I simply touch the speaker plug with my hand, so the problem isn't inside the computer.

It's unquestionably a "Ground Loop" causing the buzz, but the usual fixes of plugging the speakers into another outlet, turning off every other electrical device in the room or replacing the audio cable didn't help.

@Mugsy , are you saying touching the metal part causes the buzzing? If so, same happens on mine , an inexpensive set I bought at Target.

 

[DelJo63]

BTW: Make sure you are connecting the AC power line to a 3-pronged wall outlet that has been tested for proper grounding

 

[learninmypc]

Don't know about OP's speakers, but mine don't have a 3rd prong.

 

[Mugsy]

The MB connection to the Audio Plug is in question.

Thanks, but the PC can't possibly be the problem. The PC isn't even connected and the speaker still buzzes when you simply touch the audio plug with your finger.

 

[Mugsy]

@Mugsy , are you saying touching the metal part causes the buzzing? If so, same happens on mine , an inexpensive set I bought at Target.

Thx. I'm now looking at "Group Loop isolators" for the buzz.

But the problem is more complicated. On at least one occasion, I couldn't even boot the computer with the Ethernet cable plugged in (suggesting the computer was grounding through the Ethernet cable.)

I'm thinking now the Electrical Ground in his apartment is bad.

 

[Mugsy]

BTW: Make sure you are connecting the AC power line to a 3-pronged wall outlet that has been tested for proper grounding

The speakers are powered via a 2-pronged plug (not 3).

The Ethernet router uses a two-prong "wall wart" (AC/DC transformer.) Only the PC has a three prong ground plug.

 

[DelJo63]

The speakers are powered via a 2-pronged plug (not 3).

The Ethernet router uses a two-prong "wall wart" (AC/DC transformer.) Only the PC has a three prong ground plug.

Didn't mention speakers - -speakers powered?? really? is this a sound bar or powered woofer? NORMALLY, we speak of speakers being CONNECTED and that's passive audio only w/o AC power

the PC to wall outlet must be grounded.

 

[DelJo63]

Thanks, but the PC can't possibly be the problem. The PC isn't even connected and the speaker still buzzes when you simply touch the audio plug with your finger.

Then you better be precise in describing the wiring connections (both audio and ac) from the PC to the speakers, every box and the service it adds to the audio. We can't guess what sits in front of you and can only assume you're using commonly connected components.

 

[learninmypc]

This is very similiar to mine https://www.target.com/p/logitech-s120-speaker-system-black-980-000309/-/A-14479755

 

[Mugsy]

Didn't mention speakers - -speakers powered?? really? is this a sound bar or powered woofer? NORMALLY, we speak of speakers being CONNECTED and that's passive audio only w/o AC power

the PC to wall outlet must be grounded.

Yep, he's using a 2.1 setup with powered subwoofer.

 

[Mugsy]

Then you better be precise in describing the wiring connections (both audio and ac) from the PC to the speakers, every box and the service it adds to the audio. We can't guess what sits in front of you and can only assume you're using commonly connected components.

Sorry. I did say it was a "2.1" setup, and I've never seen a subwoofer that wasn't A/C powered.

It's an old "Cyber Acoustics A-3640R". The company is no longer in business AFAIK.
https://www.newegg.com/Product/Product.aspx?Item=N82E16836150017

 

[DelJo63]

You should be able to touch any part of the system and even the OUTER shield of the audio cable without any problem - -touching the center point of that lead will always cause issues. I can't be more clear than that.

 

[Mugsy]

You should be able to touch any part of the system and even the OUTER shield of the audio cable without any problem - -touching the center point of that lead will always cause issues. I can't be more clear than that.

"Should be"... but can't.

I'm just going to tell him to buy a "ground loop isolator" and hope he doesn't have more serious grounding issues.

 

[MaikuTech]

So now that I read everything lets back all the way up and do it my way ?
When you say upgraded his pc, what parts and components did you upgrade ?
Also his specs would help out alot so we can know what we're dealing with.
Ask your friend to take his speaker-subwoofer setup with that cord.

Plug it into a smart phone or some other device that will use 3.5mm port and see what happens.
If it buzzes on other devices, its a direct problem with the cord.
If it does not buzz or make any static or crackling noise whatsoever.
The problem will fall back directly to his mobo, you need to buy a new cord and test that out

 

[DelJo63]

Some basics: Does it work well *IF* you keep your hands off it?

 

[learninmypc]

I was going to ask the same thing, if it only buzzes when touched, why touch it? Mine ONLY buzzes (hums) when touched by hand or as I plug it in, otherwise no buzz/hum.

 

[captaincranky]

...[ ]....The cable is a standard PC Audio cord with 3.5mm din on each end (Green plug.) The cable plugs into the subwoofer. The other end causes the "ground loop buzz" simply by touching the other plug (no computer needed.)

If this is an amplified subwoofer, or contains the speaker system's amp, then it's suppose to buzz when you touch the input.

Just like if you put a guitar cable into an amp's input, and touch the center pin on the opposite end of the cable, it will buzz like hell, (and you might break something).