Copper shielding FAQ: why your guitar hums and how to fix it
If you plugged in your new kit guitar and heard a nasty hum, especially when the lights are on or other electronics are running nearby, you are not alone. This post explains exactly why it happens and how to fix it with copper shielding.
The problem is simple. The answer is simple. You just need to know what you are dealing with.
The problem: EMI and 60-cycle hum
The hum you hear is called EMI, short for electromagnetic interference. It comes from your mains power, which alternates at 60 hertz in most of North America, so you may also hear it called 60-cycle hum.
Your pickups are the cause. Single-coil and P90 style pickups act like little antennas. They pick up not just your strings but also the electromagnetic fields from every mains-powered device around you: lights, chargers, computer monitors, and appliances.
Who is affected most:
- Guitars with single-coil pickups
- Guitars with P90 style pickups
- Most blank and solid body kits with open pickup cavities
Less affected:
- Guitars with humbucker pickups. The way humbuckers are wired sends most of the interference directly to ground, which is why they are called humbuckers. You can still shield them, but the benefit is smaller.
The answer: copper shielding
The fix is to line the pickup cavity and the underside of the pickguard with copper shielding tape. When you do both and they touch at the edges, you create a partial Faraday cage around the electronics. The cage catches the interference and sends it to ground before it reaches your pickups.
It is not a perfect seal because the tops of the pickups are still exposed, but it reduces the hum significantly. For most builders it is the difference between a guitar that is unusable around lights and a guitar that is quiet enough to record.
What you need
- A roll of copper shielding tape. A 50mm wide roll from a general hardware or online marketplace will cover a few guitars and cost very little.
- Sharp scissors. Dull scissors will fray the copper and make messy cuts.
- A multimeter (optional but recommended). Lets you verify continuity across your shielding so you know every piece is connected.
- Compressed air or masking tape. To clean out the cavity before applying the shielding.
No soldering experience required.
Step by step
- Remove the pickguard. Gently pry off the tone and volume knob caps with a flat screwdriver. Work slowly, the edges are fragile. If your knobs have set screws, loosen those first. Remove the pickup selector knob and the pickguard screws.
- Cut the ground wire temporarily so you can lift the pickguard clear. You will reattach it at the end.
- Remove the control assembly (pots and pickup selector) so you can work on the cavity underside. A multi-tool spanner or socket works best on the pot nuts.
- Clean the cavity. Compressed air first, then press masking tape into the cavity to lift any dust or residue. You want a clean wood surface so the copper tape sticks properly.
- Line the pickup and control cavities with copper tape. Cut rough lengths first, lay them down one at a time, and overlap every edge. No bare spots. Leave a small amount of tape sticking up over the top edge of the cavity, because this is what will connect to the pickguard shielding.
- Line the underside of the pickguard with copper tape. Cover the whole underside. You can go close to the edges for a tidy look, or just cover the area that will contact the cavity edges you left exposed. Cut out the pickup and control holes with a sharp blade after the tape is down.
- Test continuity with your multimeter. Touch two separate points on the shielding. If you get continuity, every piece of tape is connected and your Faraday cage is complete. If not, add a small connecting strip where needed.
- Reinstall everything in reverse order. Reattach the ground wire, put the control assembly back, seat the pickup, and screw the pickguard down. The copper tape on the pickguard will press against the copper tape on the cavity edge and complete the cage.
Do I need to shield the output jack cavity?
Some builders do. Most do not need to.
The short length of wire inside the output jack cavity is not a significant antenna compared to the pickups themselves. In most cases you will not hear a difference. If you want to be thorough, you can shield it, but you must connect the jack cavity shielding to the main cavity shielding, either by running a thin strip of copper tape through the wire channel or by using wire and solder. Isolated shielding does nothing.
Watch the full walkthrough
Marty walks through the whole process on an ST-style kit, including the small tricks that make it tidy (masking tape for dust removal, scissor technique, where to overlap).
Read the full written guide: Copper Shielding a Kit Guitar
Still hearing hum after shielding?
Drop a comment below and tell us:
- Your kit type (single-coil, P90, humbucker, mixed)
- Which cavities you shielded
- What your multimeter showed for continuity
- What the hum sounds like (constant buzz, dies when you touch the strings, gets worse near a specific appliance)
We and other builders will help troubleshoot. If shielding completely solved the problem on your build, share the details so others know what to expect.