Getting rid of outside interference in 4 steps
For many of us who love the sound of single coil pickups (eg. classic Strat or Tele) we are familiar with 60 Hz hum, radio stations, and cell phone signals coming through our amp. This is electrical interference that our single coils are especially susceptible to, and yet we refuse to give up single coils, we just love the tone too much! Humbuckers are a great way to fight this 60 Hz hum, if you have ever played a guitar with a humbucker and a true single coil you can easily hear the difference, but a lot of players complain that too much tone is lost when the hum is “bucked.” The truth is, you can stick with your old single coils as long as you follow a few DIY procedures that are guaranteed to reduce the noise to an absolute minimum. Even if you have humbucking pickups these steps will help reduce the overall noise of your rig.
Step 1. Shielding Paint
With the pickguard and electronics removed from the guitar, you can paint shielding paint from Stew-Mac on the inside of the control cavity and the pickup routs. Two or three coats (allowing it to dry overnight between coats) should provide enough coverage. All grounding material must come in contact somehow with the back of the potentiometer (ground). Connect a ground wire from the paint to the back of a potentiometer or paint up to a screw hole so the paint comes in contact with the copper tape on the back of the pickguard (see step 2).
Step 2. Copper Tape
This tape (also from Stew-Mac) is great for sticking to the back of pickguards and totally blocking out any interference. The tape is grounded by coming in contact with the switch and potentiometer casings.
Step. 3 Leads
Keeping all electrical connections to an absolute minimum length will reduce the chances of interference.
Also, twisting the positive and negative leads from your pickups (as seen on this Jazz Bass pickup) will help cancel interference. It is debatable whether this makes a noticeable difference in passive equipment, but it won’t hurt, some like it for aesthetics and wire manageability.
Step 4. Final details
Having a good quality, shielded instrument cable free of cracks and keeping it as short as possible will help tremendously in avoiding interference.