View Full Version : Speaker Hum From Powered Speakers when Plugged In

May 22nd, 2017, 06:58 AM
I am getting a hum (different volume levels) in three different sets of powered speakers I am trying to setup my retro lab with. On all 3, the hum is coming when they are plugged in. Plugging in the audio cable to the computer or leaving it disconnected makes no difference.

The speakers work fine in Windows on several different computers.

I have plugged them into several power strips I have setup behind the computers as well with the same issues each time.

Anything I can do / try / move to try and alleviate or quiet the hum? I have a pair of Harmon Kardon's I really want to use but the hum seems to be the worst on them...the hum isnt so bad that it drowns out sound on the speakers when used in Windows or DOS (the sound is pretty good), but you can audibly hear it when you turn the speakers on or when they are idle and not playing anything and its just annoying!...hard to tell if its affecting the overall sound as well. The other two sets I tested on are older speakers with the hum being about 20 - 25% quieter.

The Harmon Kardon's have a removeable Power Supply cable, where the other two sets have power cable directly wired into the speakers...I have a pair of JBL's that I havent tested yet as I need to find power brick for them, but figuring its gonna happen there to.

May 22nd, 2017, 07:32 AM
Humming speakers usually has to do with some sort of ground look, usually from the source, but could be from the speaker power supply, You have the hum on multiple speaker sets, so I am going to guess it's the source.

Get yourself one of these: https://www.amazon.com/BOSS-Audio-B25N-Ground-Isolator/dp/B000LP4RMG

May 22nd, 2017, 07:45 AM
I plugged them all into a couple different power supplies and same issue each time...

The audio cable is never plugged into the source as the hum happens just with the power plugged in. Plugging in or removing the audio cable connection makes no difference...

For the ground loop...is there anything I can try or test to find out where its coming from?

May 22nd, 2017, 07:51 AM
Speakers being analog devices are quite susceptible to power supply (ripple) hum. I've got a set of Jensens that I purchased new that exhibited hum. Replacing the on-board large electrolytics cured the problem.

May 22nd, 2017, 09:21 AM
Your outlets might not be properly grounded. However try plugging everything into the same outlet. My other hobby (other than computers and gaming) is music production so have a studio setup with a bunch of music hardware and have no ground loop hum currently, but I did at my old place.

One thing I did at my old place that helped was plugging into a GFCI outlet... the hum was still there but it was only noticeable when turned up too loud. The other thing might be improper gain staging. Like the speakers themselves turned up too loud when the computer is a low volume.