AC line noise is driving me INSANE!!!!

toddgv73

New member
Greetings fellow producers! I have been slowly setting up a home bedroom studio (apartment) and I have been battling ALOT of AC line noise that is somewhat manageable with my mics and clean tone guitars but if I introduce overdrive then it just becomes unbearable. I have separated ac power cables from audio cables the best the space will allow. I have tried ferrite chokes (ckoked 3 of them furry sumbitches and NOTHING) jk. I've tried humX. I've tried various ground loop isolators and I have everything running through a Furman m-8x2 that supposedly has AC filtering in it.

My question for YOU is ........ What next? Do I need a higher end version of my furman? is there something else in the audio device world that will help? Do I need to be looking at hardware and electrical stores for some sort of device to give better filtration? Please help, I'm at wits end with it. Please respond if you have overcome this issue and if so, how? Is this a $5,000 problem or $500 problem? and before the sarcastic "just move to house" or "have your landlord rewire your apartment" start rolling in I ask for realistic feedback only
 

Folkcafe

Active member
Here is an explanation on power conditioners I wrote for someone on another forum. Noise filtering in them is for line noise coming in from the pole and that is not the kind of noise you have. So Furman or what ever isn't it. What are you going into with the guitar. Computer power supplies and grounding can be problematic. Buss powered interface?

Any way,

Surge protectors/Power conditioners.

Two different functions, sometimes in one unit. Protection and filtering. The most extreme solution I've seen was in a well known high end mastering suite that ran off a pure sine wave inverter and a room full of batteries. Kind of the ultimate filter from the power grid. Batteries charged at night. I did something similar with a recording rig I sent to do some classical recordings in some old eastern European countries years ago.

A lot of so called power conditioners or surge protectors are simply a power strip/distro with a component called a MOV (metal oxide varistor). It is tied to ground and if the voltage reaches a threshold it shunts to ground. They are reasonably fast but so are transient voltages from lighting. Better units will have filtering. This is for line EMI and RFI typically. Better units will also have good size inductors.

So what is your signal chain end to end?
 

rob aylestone

Well-known member
I’ve been running one piece of kit in a theatre via a computer UPS. One of the older designs that doesn’t switch but runs the inverter from the battery 24/7 and just charges the battery, so the output waveform is not connected to the input ac at all. The battery now is very knackered, lasts about ten minutes but that doesn’t matter. It powers an X-32 now which tolerates the noisy mains better than the analogue Yamaha it replaced that was unusable. Lots of cheaper ups devices now seem to switch the mains when it fails so they don’t work for this purpose.
 

Mickster

Well-known member
Not knowing what country you live in makes it a little more difficult to make suggestions. So....have you double checked the actual outlet wiring to be sure it's not wired in reverse or without a ground? Even one outlet can cause that problem. Have you had the issue the entire time you've lived there....or did it start at some point? Did you add lighting or some other appliance lately? If you unplug a local lamp or other device does the noise go away or change? If you "re-assemble" your setup one device at a time does a certain device introduce the noise....vice versa....removing one device at a time does the noise go away or change? Do you have a digital power meter on your home? You get the idea. Sorry if you've done all that previously.

Mick
 

keith.rogers

Bobby'); DROP TABLE USER
Greetings fellow producers! I have been slowly setting up a home bedroom studio (apartment) and I have been battling ALOT of AC line noise that is somewhat manageable with my mics and clean tone guitars but if I introduce overdrive then it just becomes unbearable. I have separated ac power cables from audio cables the best the space will allow. I have tried ferrite chokes (ckoked 3 of them furry sumbitches and NOTHING) jk. I've tried humX. I've tried various ground loop isolators and I have everything running through a Furman m-8x2 that supposedly has AC filtering in it.

My question for YOU is ........ What next? Do I need a higher end version of my furman? is there something else in the audio device world that will help? Do I need to be looking at hardware and electrical stores for some sort of device to give better filtration? Please help, I'm at wits end with it. Please respond if you have overcome this issue and if so, how? Is this a $5,000 problem or $500 problem? and before the sarcastic "just move to house" or "have your landlord rewire your apartment" start rolling in I ask for realistic feedback only
A picture of how you have stuff configured, or at least a good description of the pieces, how they're connected and where power to each piece is coming from would be extremely helpful.

"AC line noise" can mean a lot of things, and, as suggested, might not be line noise at all, but something coming into the chain from who knows where.

If you have an audio interface (assuming you do) and listen with headphones when it is powered on (USB power or wall wart?), nothing else plugged in, do you hear noise like static, or AC hum or interference, or? Is the computer a laptop or desktop? If it's a laptop, and the interface is connected to it, does the noise change whether the laptop is plugged in or running on batteries? Etc., etc. Keep adding a piece, and changing just one thing - even a cable change - to see if you can determine where the noise is entering, and what makes it worse.

Oh, and what does "introduce overdrive" mean? Add a pedal to the chain? AC powered or battery powered? Sound the same either way? ....
 
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