How to reduce/eliminate RF noise in my home studio?

February 19, 2008 1:31 PM

My little bedroom studio could use some help. It's hard to find a spot where the mics and guitar pickups don't pick up RF noise.

And when I do find a spot, it's usually closely facing a wall, and/or too far away from the recording computer. Actually, even with the computer off and the lights off, the guitar picks up a ton of gnarly RF static.

I also have a weird issue where my reference monitors pick up even *more* noise when I turn off the LCD monitor on my recording PC. I don't get it :/

I've googled up quite a bit of info on RF noise online, but most of it goes right over my head when they start talking impedance, Hz, etc. It helps to know the science, but I really just need some practical things to try at home. Tips, tricks, suggestions?

posted by scottandrew to technology (7 comments total)

Troubleshooting the source of the noise and figuring out how to kill it off can be difficult. The little FCC sticker on electronics sold in the U.S. says,"orient the component until the noise goes away", and it's easier said than done.

Your music equipment has plenty of amplifiers which normally do what you bought them to do -- transform low-level signals into higher-level (louder) signals. Unfortunately, if anything other than your music sneaks into the device before the amp circuit, you'll hear it amplified, no matter how weak it might be. Folks who live next to radio antennas sometimes experience this issue, as well.

Your best bet is to provide metal shelding around everything which is generating and picking up the signal.

In your case, that's making sure the PC shielding is in place. If video is really the culprit, try shielded cables. They're more expensive, but will cut down on EM "noise".

Whatever you're using in your music apparatus should also be shielded -- from components (hopefully they have metal cases, and are put together correctly) to ALL your cables. Try XLR gear (with adapaters, if necessary) or shielded audio cables.

The noise may be travelling through your electrical circuits, too. Try using a different outlet (or an entirely different room) and see if the issue is still present.

In the end, what you want is metal shielding or plenty of space between your noise-generating and noise-amplifying equipment. Keep power cords and audio cables away from each other, too.
posted by catkins at 1:41 PM on February 19, 2008 [1 favorite]

Another thought -- cheaper audio equipment tends to be very suspectible to interference. It all comes down to the physical and electronic design, and a more complex/resistant design costs more to build. Sigh.

I only mention this because you said it was a "bedroom studio," which makes me think "audio on the cheap." :>

Also -- the more components you introduce into the system (effects boxes, whatever) the more chances there are for interference to get into your mix. Try eliminating components and see if one or two are picking up EM noise. If so, remove/replace them with something better.

If you upgrade equipment, here's my preference on where to spend the big bucks:
1) Mics. Hands-down the most important component.
2) Amps. The cheap ones that advertise tons of watts are bad news.
3) Cords. Get them NEW and shielded. XLR phantom power is also helpful. (http://en.wikipedia.org/wiki/Phantom_power)


4) Music lessons.
...
5) Profit.
(sorry, couldn't resist)
posted by catkins at 1:52 PM on February 19, 2008 [1 favorite]

Make sure everything is off. Record tracks separately, works better so that idle equipment isn't causing the problem.
posted by Ironmouth at 2:20 PM on February 19, 2008 [1 favorite]

a) Yeah, new, shielded cables. XLR balanced would work for any noise that's picked up via your cords. Not sure what phantom power does to help noise, it's only there to power condenser mics. But if it's getting picked up by your pickups, you'll have to stop it at the source. Or get humbuckers.

b) All equipment plugged into the same outlet, or at least the same circuit.

c) Fluorescent lights, especially CFLs. Cheap and older CFLs can put out some horrifying RF noise. I had a bulb on a hallway light timer that lit up fine, but when it was on, my cell phone simply didn't work. Six months later when the bulb burnt out I discovered that my cell phone worked again. Ugh.

d) What kind of noise? 60 or 120 cycle hum? 60 cycle sawtooth or square? Or something else?
posted by gjc at 8:21 PM on February 19, 2008

The ham radio operator's RFI mantra is grounding, grounding, grounding! Establish a single-point ground and make sure everything connects directly to it. Read more.

As others have said, use balanced (xlr) connections whenever possible, as they're inherently interference-resistant. If you find unbalanced connections you just can't eliminate, get some clip-on ferrite chokes and use them liberally. (Wrap the cable as many times through the bead as possible, to multiply its effectiveness.)

Really, though, you're flying blind here until you learn enough about electricity and magnetism to have a "feel" for how interference happens. I don't know your appetite for physics and electronics courses, but an intuitive understanding of this stuff is what separates a mixer jockey from a studio engineer.
posted by Myself at 1:46 AM on February 20, 2008

I lived for 18 months in a duplex 2 blocks away from a community college radio station's tower. We got that damn station on EVERYTHING. (answering machine, computer speakers, TV, fillings...okay, I kid on that last, but not by much.)

We dropped by the college and talked to one of the electronics department guys. He gave us some stuff: something to plug in between the TV cable and the TV itself, and what was more useful, some sort of big metal circle to wrap the power cords around.

I have no idea either what it was called or how it works, exactly, but it did help a very tiny bit. (Avoiding rant about damn station, horrible property manager denying that anybody'd ever had that problem, etc., etc.)

And catkins's suggestion about trying different power outlets is a good one; some of the outlets in that house were in better condition and seemed slightly less likely to carry the radio station. You might even try actually replacing the outlet, if you have access to the fuse box.
posted by epersonae at 9:02 AM on February 20, 2008

Guitar pickups?

Are you sure you mean RF noise? Not line hum? In other words, are you playing a telecaster or stratocaster -type guitar? Humbucker pickups were invented because of just this reason. The gyrations you describe seem to indicate single-wound pickup issues.
posted by lothar at 3:48 PM on February 20, 2008