Need help a diagnosing amp/pa noise problem in my house.

Nick · Post by **Nick** » Tue Nov 18, 2014 2:32 am

As there's apparently many causes and searching amp hum or anything similar has proven to be a wild goose chase, and I also know there are a few electrical-types here hopefully I can get this ironed out.

Basically, it seems like anything with magnets gets seriously hummy in my house. Amps, PA, Wurlitzer, anything that has magnetic pickups/microphones going into it gives off a noticeable hum, especially at loud volumes and especially with distortion. Humbuckers behave a bit better but don't resolve the issue entirely. It is the kind of hum that gets better/worse depending on your angle to the amp. Touching the strings does not make it go away. With the exception of the PA, I have tried all my gear in other buildings and have had no problem with noise. I have tried many different cables and still get this hum even if I'm going straight to the amp from guitar.

To summarize the amps themselves are quiet until I plug in a guitar or microphone. If I plug in a keyboard or something digital, there is no issue. Also all my outlets test postitive for ground connection with one of those little tester plug things. I've tried plugging the amps straight to the wall and through different outlets. No luck.

So I've ruled out:
Guitars
Amps
Cables
Surge Protectors/power supplies
Outlet ground

Would a product like a hum-x or a power conditioner work for me? If I need to call an electrician what kind of repair am I looking at (I'm not sure all electricians would say I have a problem if my only issue in the house is the fact that my amps hum loud). The noise is tolerable for practice and gets buried under the noise once we start playing, but my new band plans on recording in my basement and this is going to be an issue.

Thanks in advance.

Sloan · Post by **Sloan** » Tue Nov 18, 2014 2:51 am

Fluorescent lights and dimmers are known to sometimes cause probz.

Nick · Post by **Nick** » Tue Nov 18, 2014 3:37 am

I only have fluorescent lights in the basement (band room), with the exception of one of the fish tanks upstairs. I've heard that about florescent lights before and tried keeping them off, did not help.

No dimmers are in the band room-only ones are in the bedrooms, usually off when I'm downstairs.

Would a hum-x or power conditioner work? I'm pretty sure a noise gate might work but I'm afraid of cutting out too much when recording.

Sloan · Post by **Sloan** » Tue Nov 18, 2014 6:31 am

it definitely won't hurt to try one. also have you tried using those cheap ground lift plugs? sometimes hum issues are just dumb and you never know!\

also, i would try moving the guitar around to see if you induce more or less hum in certain spots. put it next to amps or anything generating power at all. even right up on the wall if it gets stronger there.

NickS · Post by **NickS** » Tue Nov 18, 2014 8:56 am

http://custommagneticshielding.magnetic ... t-and-foil

Seems to me you have a magnetic field that is being picked up by the coils in the guitar/microphone, as you say it varies with the guitar's position. I get this when I'm standing by the amp - pickup from the mains transformer - and the further I move from the amp the better it is. Then I notice pickup from the lighting. You could also be picking up field from the rooms above/below if any - if your floor is someone else's ceiling. Does moving away from the amp help?
Distortion adds gain so anything picked up by coils will sound louder.

Nick · Post by **Nick** » Tue Nov 18, 2014 3:03 pm

When I get home I'll try turning off the Wi-Fi, and seeing if that helps.

I really don't know what else could be causing it, could radon be a cause? If so I better get it checked/sorted asap.

So what I guess I'm getting is if it had to do with the power not being clean i would get hum even without being plugged in, which i'm not.

NickS · Post by **NickS** » Wed Nov 19, 2014 1:22 pm

If you get the hum with just the guitar plugged in I believe the power supply to the amp is not a problem. Normally unplugging the guitar shorts out the input so any hum left would normally be down to the smoothing or pickup from AC power to the tube heaters (many heaters in the preamp stage are now DC fed these days).

[edit: to make more sense]

Sloan · Post by **Sloan** » Wed Nov 19, 2014 10:48 pm

interested in the development of this issue.

here's some neat gov'ment emf info:
http://www.niehs.nih.gov/health/topics/agents/emf/

NickS · Post by **NickS** » Tue Dec 02, 2014 9:19 am

How's it going?
I'm hoping to phase out my Ethernet-Over-Mains which is a potential source of serious noise on mains that seems to get transferred into my signal chain through the filters on switch-mode PSUs - ironic.

Nick · Post by **Nick** » Tue Dec 02, 2014 1:26 pm

Sorry, been busy the past two weeks. The noise is definitely directional. Depends on which way the pickups are facing, I've tried moving the amp's direction and nothing.

I did do a radon test last week which came back positive with a 4.8 reading in the basement (4.0 is the epa "safe" limit) so we'll be dealing with that soon. Not sure that can effect magnetic fields but there's also better reasons for addressing that problem.

I bought a cheap old Ross Noise Gate pedal on ebay to try but it ended up being DOA....

I'll try to make a video soon.