AC hum / ground loop
Posted: Thu May 20, 2021 4:06 pm
I have been dealing with a couple of diff hums coming from my PA gear that is now in service as my home theater.
1. Constant very soft hum, though not low. I tried finding the freq via Youtube sine waves but was unsuccessful.
2. When I turn on the light in the bedroom that shares an adjoining wall, there would be a STRONG and obvious hum, diff tone. I know about LED interference and was ready to explore that.
3 I was installing a new light fixture today in the foyer, adjoining in the other direction, and heard a third sound yet. (Prev owners had "Uncle Louie" do a lot of the home improvement. "Interesting" electrical design commented the electrician who updated my main panel.)
What I did:
Lifted the signal cables up off some extension cords in the corner, which were powering the Crown amp and Ahsley 3102 EQ. Did nothing.
Unplugged the amp and EQ (that share power via a passthrough plug), and plugged them in across the room into the same outlet my PC uses, in an effort to eliminate ground loop hum, either actually or troubleshooting wise. This reduced the #1 hum to very very low.
Unplugged the line in from PC to EQ, did not remove any hum.
Cut to the chase, already.
Removed the Ashley EQ from the signal path and ALL the hums of all stripes are gone. What's up with the EQ? I got it used off Ebay in 2012. It's SEEMED to do a good job at gigs, though the general sound levels may have covered it. Is there any hope for it? As an older model I'm sure it lacks design to resist LED interference.
1. Constant very soft hum, though not low. I tried finding the freq via Youtube sine waves but was unsuccessful.
2. When I turn on the light in the bedroom that shares an adjoining wall, there would be a STRONG and obvious hum, diff tone. I know about LED interference and was ready to explore that.
3 I was installing a new light fixture today in the foyer, adjoining in the other direction, and heard a third sound yet. (Prev owners had "Uncle Louie" do a lot of the home improvement. "Interesting" electrical design commented the electrician who updated my main panel.)
What I did:
Lifted the signal cables up off some extension cords in the corner, which were powering the Crown amp and Ahsley 3102 EQ. Did nothing.
Unplugged the amp and EQ (that share power via a passthrough plug), and plugged them in across the room into the same outlet my PC uses, in an effort to eliminate ground loop hum, either actually or troubleshooting wise. This reduced the #1 hum to very very low.
Unplugged the line in from PC to EQ, did not remove any hum.
Cut to the chase, already.
Removed the Ashley EQ from the signal path and ALL the hums of all stripes are gone. What's up with the EQ? I got it used off Ebay in 2012. It's SEEMED to do a good job at gigs, though the general sound levels may have covered it. Is there any hope for it? As an older model I'm sure it lacks design to resist LED interference.