Odd humming noise

[beasleybodyshop]

I have a strange mains hum in my apartment -

Im getting a 187Hz hum whenever I turn up any of my guitar amps. If im using a singlecoil equipped guitar, the hum is at its worst when its in the bridge/middle/neck position (as it usually is) and the pitch of the hum changes when i switch to positions 2 and 4 on the guitar (which is to be expected)

Now, when I switch to my les paul, there is a noticeable hum in the bridge and the neck position, but when i flip it to the middle position, it gets a little quieter - what? it has medium output pickups, and i'm pretty sure it doesnt make this humming noise outside my apartment.

I say its 187HZ because I used my RTA and measured the response with all three of my amps (Rocket clone, Express Clone, Mesa Boogie Express 5:50) I even moved the outlet plug around to different receptacles around the house. I even flipped off all the breakers except the one that the amp was using.

I'm pretty sure this is just line noise from living in an apartment, but wouldn't it be more like 60/120hz? My RTA clearly shows 177-188 HZ being the loudest frequency pushed. Anyone have any experience with taming home electrical interference?

[Jana]

187 Hz. is the frequency you hear just before the little green men come and take you away. It has something to do with the overlap from their hinklefarb calibrator.

[ToneMerc]

I bet it's power harmonic, start turning off stuff.

TM

[katopan]

180Hz is the 3rd harmonic to 60Hz. Your incoming mains is probably full of it. Sorry I don't how to help otherwise.

It's an interesting exercise to see the main waveform on a CRO (with the right CAT rated equipment for mains connection). I looked one day and here the peaks are flattened as proof of all the rectifiers hanging off the grid, taking their spike of cap charging current all at the same time. Even big domestic loads like airconditioners, washing machines and microwaves are inverter driven these days.

[beasleybodyshop]

180Hz is the 3rd harmonic to 60Hz. Your incoming mains is probably full of it. Sorry I don't how to help otherwise.

It's an interesting exercise to see the main waveform on a CRO (with the right CAT rated equipment for mains connection). I looked one day and here the peaks are flattened as proof of all the rectifiers hanging off the grid, taking their spike of cap charging current all at the same time. Even big domestic loads like airconditioners, washing machines and microwaves are inverter driven these days.

Power Harmonic? I had no idea my mains hum was part of an 80s metal band

So its safe to say there is nothing I can do about this? Could I use an isolation transformer between the wall socket and my amp? Would that do anything?

[M Fowler]

I had such a bad harsh raspy hum coming through my house and found out it was from all those helical light bulbs, they are in a drawer now and I give them out to my kids when they visit.

[Structo]

Could it be a ground problem with the wall/ breaker wiring?

Really strange it would do it with different guitars and amps.

[JoeCon]

Mark

That's the ballast in those Compact Fluorescent Lamps causing all that noise.
Where do you think all the carbon comp resistors and leaky caps go?? Right into those cheap ballasts!! Now change those out to some metal film resistors and some Sozo caps and those CFL hum...DOH!!