Hi, I followed Ethan's advice for a dimmer switch and installed a Staco 171 in the wall. But getting within about 3 feet of it with a single coil guitar even at low gain gets a horrendous hum/buzz. The guitar cavity is shielded. I have a small home studio and I could stand far enough away from it if i really need to but I'd rather not. I suspect the Staco needs shielding, though the article doesn't mention this requirement. I am thinking of removing it and installing it in an external aluminum box. Anyone have ideas I can do to save the wall switch project? Thanks!
I never used a Statco but I looked it up and I see what it is. Is your house electric the kind with plastic electrical junction boxes? In my neck of the woods we are required by code to have metal boxes and conduit for fire safety reasons but it also helps to shield electromagnetic fields. Even though, Strats etc. still hum pretty good in my basement because of all the other gear.
So anyway, that Statco autotransformer (like a tiny Variac) is obviously creating an EMF causing your guitar to hum. (You know how to keep your guitar from humming? Teach it the words! Ba-dum-crash).
If your house doesn't have metal boxes putting it in a metal box may help. Mu-metal shielding is expensive but is supposed to be superior because it works differently. See here en.wikipedia.org/wiki/Mu-metal
I have worked on gear that used it to shield the power supply transformers but I never used it on DIY projects...but I've considered it. You can get Mu-metal foil and lining your plastic (or metal) boxes may help. You will read that the thicker stuff works better.
Teach it the words! Thanks for the replies. Yes, it is in a plastic box. I will probably remove it completely and make an external box but thanks for the mu-metal info. I've been thinking that my amp picks up noises in general and my computer throws noise. Ethan says he has his computer turned off and records with DAT but the computer is a pretty good digital recorder in it itself right? So I'm wondering if shielding my amp and computer might help.
Your amp picks up noise usually via your guitar inputs via the pick-up and to a lesser extent the cable. A simple way to test an amp for any noise it self-generates is to short the input. If you take a 1/4 plug with the shield screwed off, jumper the tip and sleeve together. When you plug it into your amp, you will short the input to ground. Turn up all the controls and you'll hear some noise but it should not be much. This is also actually a good way to troubleshoot an amp that you believe is giving you problems. You can even determine which stage of the amp the problem is located if you understand how the signal travels through the unit.
Your amp also is capable of "throwing" noise too and it usually comes from the power transformer. You can shield your power xformers with Mu-metal too.
The computer noise is different if it's a whining sound. I imagine that's got to do with the high frequency clocking and not the low freq power line noise.
As far as your plastic box, maybe you can find and electrician who will replace your plastic with a metal box. Then you can have a nice, permanent dimmer installation. On the other hand, it might still hum a little so it's probably a good idea to test a metal box before you tear up your wall. Make sure you earth ground (green wire) your metal box (not to be confused with the common (white wire)! BTW, Mu-metal shielding does not require grounding; it does not "run" the noise to ground like a regular metal box or Faraday Cage, it's magnetic permeability kind of absorbs the EM energy...until it saturates...