Hum in speakers, and suggestions for stopping it

Well, you could try something as cheap as “cheater plugs” that may solve the problem right from the get go.  Best of luck.

I would get an inexpensive AC line tester (Home Depot/Lowes) and check that the outlet you are using is wired correctly and also ( just for jollies) check the outlet that the PowerPlant is wired correctly as well.  Fix whichever one is the problem should that come up with the tester.  

Are both amps plugged into the same outlet? If so and if you can get an extension cord and plug one amp into another outlet, preferably one on another circuit. See if that cures anything. The outlet tester and cheater plug are also worth looking into for troubleshooting.

Are your amps and other equipment now on different outlets?

Do you have the amps next to the speakers? I had a Velodyne sub next to one speaker and a hum from that speaker even when the system was off. I moved the sub and problem was gone.

Phil

Your best bet is to get plugged back into a PSA PP.  The PP3 is indeed small for 2 x 350W amps.  Try plugging one into the wall and one into the PP3.  One amp should be good in a PP3, if so, you can find another PP3.  Or just upgrade to a PP10 or PP12.  I have the PP10 and swear by it.

Jerry

Have you tried unplugging everything in the shared circuit to see if there is a specific culprit? Put a meter mic on the speaker and walk around unplugging stuff with a stopwatch. If the hum exists in the wall but not through the power plant, my would be there is noise on the neutral or ground and it’s finding the biggest transformer tap in the whole house circuit to land on. The benefit of a dedicated circuit - since all circuit neutrals come together in the panel anyway, is really the ground between the panel neutral/ground and earth / waterline. You need to get that noise to have a preference to go elsewhere. Cheater plugs - and I believe hum eliminators - are basically lifting the ground. If you can find the problem, you could put a cheater plug there and not at your amp. 
 

To me, a cheater plug is a simple test. I’ve been lucky in my house that I haven’t had this issue - but I have chased it through hospital construction sites before. I actually had a project where we solved the problem by installing a large, dummy load transformer in an IT closet. The noise on the line preferred that load to the IT switches. If you have a spare amp lying around that has a larger transformer than your amps - try plugging that into the same circuit. 

Start unplugging components and plug back in one at a time. Coax for cable, hdmi cables, and Ethernet and like mentioned power cords next to speaker cables all can send signal to a power amp to amplify it. It can be irritating until you can identify the source. 

“pureclarity

12-30-2023 at 07:23am

Start unplugging components and plug back in one at a time. Coax for cable, hdmi cables, and Ethernet and like mentioned power cords next to speaker cables all can send signal to a power amp to amplify it. It can be irritating until you can identify the source. “

SOMETIMES it’s this easy. But definitely start there. Ground loops are common.

Sometimes it’s a grounding issue with the house breaker panel. We lost the connection to ours a couple decades ago (in 1972 they used a braided steel connection between ground/neutral on the breaker panel and a copper water pipe) which of course, due to electrolytic corrosion failed and I just last month watched our electrician at our new house in TN connect a braided wire to a copper-plated steel rod with a CLAMP. A STEEL clamp. Iron rust doesn’t conduct electricity - although copper oxides DO.

When I put in my ham radio tower I used thermite gadgets (Erico Cadweld GT1161V One Shot Ceramic disposable body https://a.co/d/jceML9A ) to weld the solid copper wire to the grounding rods and will do this with our new house in Tennessee shortly - right after final inspection - the steel clamps are industry standard (CODE) and are crap (can I say this here?).

Something like THIS is a good investment for starters to make sure your wiring’s right (like HOT black wire to little prong): Klein Tools RT210 Outlet Tester, Receptacle Tester for GFCI / Standard North American AC Electrical Outlets, Detects Common Wiring Problems https://a.co/d/3NI34IS

Good luck, keep us posted.

BTW, anyone looking for the Cadweld gadgets, they’re available elsewhere much cheaper. When I bought ‘em they were about ten bucks (yeah, in THIS century, about 12 years ago). 

if you've moved your equipment recently and now have speaker hum, it could just be - as normb was driving at - speaker cables interacting with signal or power cables. Try moving the speaker cables around a bit, this has worked for me under similar circumstances. 

Good luck, and Happy New Year,

Rob

If the amp is 5 years or older... a lot of the times is a capacitor or tube ageing. If you have restacked your components, the power from one may interfere with the other component if they aren't shielded from one another. Move any electrical devices away from the amp one by one to see if one of those resolves the problem. Some older amps who had wooden cases had a metal cover below to shield the electronics from florescent lights which caused buzzing in the speakers If none of that helps, locate a dumpster near your house. oh... make sure the positive speaker wire wasn't accidently connected to the negative.

Thanks, everyone. Appreciate the input.

I've done all the sleuthing and the culprit is definitely the outlet/wiring to the room. Going to live with the hum till I figure out the best solution.

I'll post again if I have a breakthrough in the next month or so.