Sign in with
Sign up | Sign in

Reply to this thread

Discussion

Started by LoonyLinee | | 29 answers
Laptop power cable causing weird noise through speakers
Hi, I have a strange problem. it's similar to some I've read about only I have a strange static/feed back/white noise type of noise which comes through my speakers when my laptop is connected to my stereo (from the headphone socket in the laptop to the phono sockets in the stereo) or tv (from headphone socket to jack input on tv), only when the laptop is plugged into the power.

I've had this set-up for sometime now though, and I can't figure out why it's suddenly causing this problem. I'm wondering if there's a problem with the actual power cable/charger thing for my Acer Aspire 5735. I've tried plugging it into different sockets and that makes no difference either. There are also no other cables near it... :( 
  • By posting on this site, I confirm I am over 13 years of age and agree to abide by the site’s rules.

October 14, 2014 6:51:29 AM

I'm an idiot. I get the same problem with white noise and humming, but only when the AC adapter is connected. I get it out the 3.5 mm audio plug as well as through the USB and an external sound card. toldyouso, what ground loop solution do you recommend.

June 30, 2014 3:17:04 AM

I have found it very amusing reading about ground loop noise on the web - people blaming capacitors, power supplies, mobile phones, mismatched impedance, people suggesting low pass filters, adapters and ground loop isolators, yadda yadda, sometimes I do wonder how people can be so daft. This is not ASIC design we're talking about here, this is a ground loop. This is really not difficult. It's a ground loop. Think about the problem for a second. Stop panicking, stop trying to fight fire with fire, stop what you're doing and just think about the problem for a moment. The solution is staring you in the face. If you can't work out what it is then shame on you, you are an idiot.
April 17, 2014 10:58:57 AM

I had a similar problem to LoonyLinee (noisy laptop when power cord plugged in). I am using USB "line" output from laptop to pro audio equipment ... After reading the posted solutions I thought some of you might be interested in a solution that worked for me.

Using a standard Toshiba computer and power supply (this should be irrelevant) -- I plugged the power supply into a simple three prong input and two prong output "cheater" AC adapter -- and then plugged the "two" prong side into my wall socket (therefore removing ground connection).

This simple adapter can be purchased from eBay for a couple of bucks (if you don't have one handy already). -- Or you might find one at your local hardware store :-)
March 6, 2014 1:35:26 PM

It is a ground loop problem. The cheapest easiest way to correct the problem is to plug your laptop in using one of the adapters you use if your plugs in the house don't have a ground prong. This isolates the ground from your laptop. Worked GREAT for me!!!
January 15, 2014 7:40:10 AM

LoonyLinee said:
Hi, I have a strange problem. it's similar to some I've read about only I have a strange static/feed back/white noise type of noise which comes through my speakers when my laptop is connected to my stereo (from the headphone socket in the laptop to the phono sockets in the stereo) or tv (from headphone socket to jack input on tv), only when the laptop is plugged into the power.

I've had this set-up for sometime now though, and I can't figure out why it's suddenly causing this problem. I'm wondering if there's a problem with the actual power cable/charger thing for my Acer Aspire 5735. I've tried plugging it into different sockets and that makes no difference either. There are also no other cables near it... :( 



Use the line out instead of the headphones and the tape in instead of the phono. Much of your issue has more to do with level and impedance matching. Turn up the output volume from the laptop to feed as much "clean" signal to the stereo as possible before turning up the stereo. There is a small level of noise from the laptop and the greater signal to noise ratio you can give the stereo the better. If you turn the level down on the laptop and then turn up the stereo the noise will be worse because the signal to noise ratio is worse.

Other issues might include cable quality and electrical grounding issues.
January 10, 2014 2:11:52 PM

I have a Samsung New Series 9 laptop that has a loud static sound only when the power cable is plugged in. This is true even when I set the speaker to "mute." The static is not 60 Hz (which is what I would expect to hear with a ground loop). In my case, my stereo system is not on and nothing else using that electrical circuit produces any suspicious behavior when in operation. The circuit does serve a stereo system and separate television speakers; but as I said, those systems/speakers are off when I have the noise. The problem is intermittent. It was bad about 30 days after I bought the laptop and the Samsung customer service guy said I'd have to send in the laptop. Then the problem went away before I packed up the laptop. It's back now, much worse in terms of loudness and consistency of the problem when the power cord is plugged in. I see some advice for shielding the power supply, but I'm not sure what I'm shielding it from unless the large stereo speaker's magnets are having an effect. (My memory of EMI diagnostics is shaky, but if the speaker is not actively being driven by the stereo system is it even possible for the magnets to cause EMI?) Next steps: (1) Use on another circuit, which will be away from the stereo and television speakers. If that doesn't work, (2) replace the power cable. Thanks for the various recommendations.
September 9, 2013 3:46:46 AM

ctini said:
I had the same problem when connecting my laptop (via headphone jack) to my Denon home theater 11.2 system. The laptop cord was plugged in to one power strip and the Denon a different one, so its not this loop thing they are talking about. I was trying to use my laptop and XMradio, online access to play music thru my Denon system. I had the same whining noise coming through my "Definitive" speakers (good speakers!) - so it's not the speakers. I went searching online for an answer that would not cost me a thing. I discovered, on my own, that if i turn up the volume on the laptop (and even on the XM radio website's) AND turn down the Denon - guess what ? ? THE WHINING NOISE WAS DRASTICLLY REDUCED! I think the Denon was trying to overcompensate for the low volume on the laptop, when it was turned up....almost like turning up the speakers too loud that the speakers can't take the power, therefore they distort. Ok, back to listening to Jimmy Buffet in concert tonight....

Girl Power :kaola: 


It works! Thank you Ctini!
June 1, 2013 11:48:21 AM

Javier Castro said:
Thanks a lot ! I will try that ! By the way there are two types of ground loop isolators, the one that will be used between the laptop power supply cable and the ac outlet and the one between the 3.5mm stereo jack of the laptop and the mixer/amplified speaker. Which one should I get ? Thanks

This one:
http://www.amazon.com/Ebtech-Hum-Voltage-Filter/dp/B000...

Or this kind:
http://www.amazon.com/PAC-Ground-Isolator-3-5-Applicati...

Even if the AC adapter has a filter problem with the voltage, a ground loop isolator is still going to have significant help. While both will help, Generally you want an inline isolator directly on your audio line. The one that plugs into the wall just cuts the loop at a different area. You'd generally want that style if you get a hum on your amplified speakers and you haven't plugged anything into the receiver or amplifier. In the image, you can see the one I suggested is the audio line between your computer and amp/receiver.

Always try the inexpensive solution first (inline). If you still have an issue, you can then get the more expensive power line filter.
June 1, 2013 2:59:48 AM

it could be on the power supply itself. Bad capacitors inside could result in bad filtering of rf signals and most of the power supply design is SMPS meaning it generates high freq in the audio range and if not filtere well will somehow creeps and outs in audio circuitry in laptop. try change power supply. try to plug the speaker if it has amplifier inside to other source of audio (ex. ipod etc.) and see if it is normal.

See all answers