The age-old single coil guitar problem… BUZZING & HUMMING.
Why won’t it stop??
To cut to the chase, your single coil pickup functions as an antenna of sorts. That is, it picks up and magnifies outside signals (electromagnetic interference) very well. Signals from transformers (such as ballasts in fluorescent lights, neon lights, computer monitors, TVs, stereos, speakers, etc). It’s insidious.
What to do? Well, there are several things that you can do. You can cave in and buy “noiseless” pickups. But you’d be sacrificing some tone when you do that as they don’t usually sound as great as standard passive pickups. You could buy a noise gate. Again, it ends up filtering out some of your highs and is not the best answer. You could only play in bars with no beer signs. (ok, I’m kidding about that last suggestion)
Shielding and good quality wiring are the REAL answer.
Your guitar’s pickups & wiring have to work together, as a team, in order to produce that great tone that you’ve spent a lot of money chasing. Good quality pickups. Great quality wiring built by someone that understands what it means to properly ground the system. Shielding that, when it’s installed correctly and grounded to your guitar’s electronics correctly, not only protects you from being electrocuted (yeah, it’s happened) but also prevents that really nasty humming and buzzing that you’ve grown to hate but have tolerated in your Strat or Tele for years.
Use copper foil that has a sticky backing (available at http://www.allparts.com or http://www.mojotone.com or http://www.stewmac.com). Cut it to fit in all of the pickup cavities. Cut a piece to fit in the electronics cavity. Be sure to connect those to the back of one of the pots with a piece of wire so they’re part of the grounding/shielding system. If you don’t, the shielding won’t function correctly. Make sure that there is a ground wire connected on one end to your electronics (solder it to the back of one of the pots) and, on the other end, to the metal on the guitar’s bridge. That way, when you touch the strings, you become protected as part of the ground.
This becomes even more important when you run overwound pickups as the coil is larger and, potentially, picks up even MORE electromagnetic interference.
The bottom line here is that your guitar really shouldn’t hum or buzz if it’s setup correctly. As players, we’ve been told for years that we just have to suck it up. That’s just the way it is. There’s no changing it. (One shop owner even tried to pass it off simply by saying that “It’s physics. EVERY single coil hums.”. No. It’s not as simple as that. If a guitar repair shop owner tells you that you just have to accept the buzz because “ALL single coils will hum and buzz”… well, take your beloved guitar to a different repair shop. One that will do whatever it takes to get that obnoxious hum/buzz out of your guitar. One that will take whatever time it takes to get it working as it should. One that CARES about you and your guitar.
In closing, though, it all starts with top quality pickups AND first class wiring.